FORM 2
THE PATENT ACT  1970
(39 OF 1970)
AND
THE PATENTS RULES  2003

COMPLETE SPECIFICATION
(See Section 10; rule 13)

A STEAM TURBINE INTERMEDIATE PRESSURE MODULE
WITH MODERATE REACTION

TRIVENI TURBINE LTD
an indian company 
of 12A  Peenya Industrial Area 
Banglore-560058.

The following specification particularly describes the present invention and the manner in which it is to be performed.
FIELD OF THE INVENTION:
The present invention relates to the field of steam turbines. Particularly  the present invention relates to intermediate pressure module of steam turbines.

TERMINOLOGY AND FORMULAS USED:
U-Peripheral velocity of rotor;
C-Steam velocity;
Cs-Tangential steam velocity;
Ca-Axial Steam velocity; and
Delta h- Enthalpy change.

The formulas employed in doing mean line calculations are as follows:
1) Loading coefficient-Delta h/U2
2) Peripheral velocity of rotor (U)= 3.147*D*N/60000 m/s
Where D=Rotor Hub Dia; N=speed of rotor in rpm.
3) Steam velocity C- 2000 *(Delta h)0.5
4) Height of the blades in a stage (H)= 2 Q/3.147*D*sina*e*C
Where Q=Volumetric flow rate in each stage (m3/sec);
D= Rotor Hub Dia;
a= Blade or Nozzle Inlet angle;
e=Degree of admission(Projected Area of nozzles/Total area of moving
blades);
C=Steam velocity(Ca-Axial velocity  Ct-Tangential velocity).
5) Flow coefficient- Ca/U

DEFINITIONS OF TERMS USED:
Meridional Plane: A plane cutting the turbo machine through diametric line and longitudinal axis.

Pitch: Circumference of the blade (2*Pi*r)/No.of blades in a row. Circumference of the blade depends on blade height (i.e.  at hub  mean or tip).
Stage: Stage herein refers to a combination of blades and nozzles.

Reaction: Enthalpy drop across the rows of blades/ Enthalpy drop across the stage.

Spanwise Reaction: Reaction across different cross-section of blade length.

BACKGROUND OF THE INVENTION:
Steam turbines comprises a plurality of blades typically configured in three modules viz High pressure module (HP)  Intermediate pressure module (IP)  Low pressure module (LP). Typically  conventional steam turbines employ either a straight parallel-sided blades (cylindrical) or tapered and twisted blades configuration. The number of stages (rows) of blades in each module of the turbine is determined depending on various factors like space  pressure ratio  power output and efficiency.

High Pressure (HP) Module  Intermediate Pressure (IP) module and Low Pressure (LP) module can be of impulse type or reaction type or combination of impulse and reaction type. In impulse stage type  pressure drop occurs only in nozzles and moving blades facilitates in changing the direction of fluid flow  thereby increasing the velocity of the flow and no pressure drop occurs in moving blades. In impulse-reaction stage type  pressure drop occurs in both nozzles and moving blades resulting in the generation of kinetic energy. In reaction stage type  flow enters the moving blades  changes its direction resulting in the increase of velocity and also undergoes a pressure drop. Generally speaking  reaction type stage is more efficient than impulse type stage due to less frictional losses  boundary layer separation losses  secondary flow losses and tip leakage losses.

Figure 1 illustrates a meridional view of conventional three stage impulse intermediate pressure module marked in a circle.

Figure 2 illustrates a sectional view of two adjacent blades depicting typical blade features.

The airfoil sections of two adjacent blades (10 and 12) is disclosed wherein the blades include a convex suction side (14 and 16)  a concave pressure side (18 and 20)  a leading edge (22 and 24) and a trailing edge (26 and 28).

The parameters which define the geometry and configuration of the blades in a row are as follows: The distance between trailing edges (26 and 28) of two adjacent blades (10 and 12) typically referred to as pitch is indicated by a letter ‘P1’. The axial length of the blade typically referred to as width is indicated by a letter ‘W 1’. The inlet and exit blade angles are indicated by letters a1 and ß1 respectively. The distance between trailing edge 26 of blade 10 to convex suction surface 16 of blade 12 typically referred to as throat is indicated by a letter ‘D1’. The angle between the chord line 21 and turbine axial direction (meridional direction) typically referred to as stagger angle is indicated by a letter ‘S 1’.

Figure 3 illustrates sectional view of two adjacent nozzles depicting typical nozzle features.

The airfoil sections of two adjacent stationary blades (30 and 32) is disclosed wherein the blades include a convex suction side (34 and 36)  a concave pressure side (38 and 40)  a leading edge (42 and 44) and a trailing edge (46 and 48).

The parameters which define the geometry and configuration of the blades in a stage are as follows: The distance between trailing edges (46 and 48) of two adjacent blades (30 and 32) typically referred to as pitch is indicated by a letter ‘P2’. The axial length of the blade typically referred to as width is indicated by a letter ‘W2’. The inlet and exit blade angles are indicated by letters a2 and ß2 respectively. The distance between trailing edge 46 of blade 30 to convex suction surface 36 of blade 32 typically referred to as throat is indicated by a letter ‘D2’. The angle between the chord line 41 and turbine axial direction (meridional direction) typically referred to as stagger angle is indicated by a letter ‘S2’.

Figure 4 illustrates a top sectional view of analytical model of hypothetical intermediate pressure module impulse moving blade and nozzle base profile obtained according to predefined operational input and set of predefined constraints.

In accordance with the present invention  the base profile is generated initially by giving the predefined input and set of predefined constraints in the blade generating software (“Axial”). The predefined input and set of predefined constraints are governed by standard design rules employed in steam turbine industry.
Hypothetical operational input data and a set of predefined constraints are as follows:
1) Operational Input Data:
Inlet pressure 15.6 bar
Exit Pressure 2.21 bar
Enthalpy 3003.95 KJ/KG
Mass flow 127 Tons per hour or 32.5 kg/sec
Speed of Rotor Drum (N) 5625 rpm

2) Predefined Constraints:
Parameter Value
Flow coefficient C/U 0.45 -0.65
Loading Coefficient
Delta h/U2 1.8 – 2.8
Exit Swirl -15 deg to +15 deg

Table 1 elucidates the geometry defining parameters at hub of moving blade profile of figure 4. As the blade profile in question is of cylindrical blade  the geometry parameters will not be varying spanwise across Hub  Mean and Tip except parameters associated with radius from axis of rotor drum like pitch etc.

Table 1
Parameter Hub Section(H-H)
Chord 24.38 mm
Inlet Angle 40.13 deg
Exit Angle -58.13 deg
Leading edge radius 0.65 mm
Stagger Angle -13deg
Trailing edge radius 0.2 mm
Unguided turning 10 deg
Angle of Attack -13 deg
Area 90 mm2
Axial chord(width) 23.68 mm
Camber 98.26 deg
Maximum Thickness 5.377 mm
Pitch/Chord 0.536
Radius at CG 375 mm
Solidity 1.863
Throat/Pitch 0.5
Tmax/Chord 0.22

Table 2 elucidates the geometry defining parameters at hub of nozzle profile of figure 4. As the blade profile in question is of cylindrical blade  the geometry parameters will not be varying spanwise across Hub  Mean and Tip except parameters associated with radius from axis of rotor drum like pitch etc.

Table 2
Parameter Hub Section(H-H)
Chord 24.5 mm
Inlet Angle 0 deg
Exit Angle 74.56 deg
Leading edge radius 0.65 mm
Stagger Angle 56.5 deg
Trailing edge radius 0.25 mm
Unguided turning 6 deg
Angle of Attack 56.5 deg
Area 52.5 mm2
Axial chord(width) 13.59 mm
Camber -74.56 deg
Maximum Thickness 3.506 mm
Pitch/Chord 0.7071
Radius at CG 375 mm
Solidity 1.414
Throat/Pitch 0.233
Tmax/Chord 0.143

Figure 5 illustrates a plot showing nozzles and blades across the stages of the intermediate pressure module of figure 4 on x-axis vs reaction on the nozzles and blades on y-axis. The odd numbers on the x-axis represents nozzles and the even numbers on the x-axis represents blades. It is evident from the figure 5 that the reaction on the impulse blades of the IP module of figure 4 is zero.

Figure 6 illustrates a plot showing stages of the intermediate pressure module of figure 4 on x-axis vs efficiency across the stages on y-axis. Several simulations are run by varying the predefined constraints and one iteration within the predefined constraints for which maximum efficiency is obtained is plotted. It is evident from the figure 6 that the total to total efficiency across the stages varies from 85% to 88% and total to static efficiency varies from 81% to 84%.

The design concern herein is to obtain an optimized intermediate pressure module having moderate reaction twisted blades with high efficiency confining to the space and above mentioned predefined constraints.
Several techniques have been disclosed in the prior art optimizing moving blades and nozzles of steam turbine based on various parameters.

US Patent no. 5203676 filed on March 5  1992 titled “Ruggedized tapered twisted integral shroud blade” discloses an optimized tapered and twisted rotating blade for the fourth rotating blade row wherein a shroud segment is integrally formed on the tip of the airfoil portion such that the shroud is dimensionalized according to materials used so that the tuned frequencies remain the same regardless of materials used  based on changes in young’s modulus due to use of different materials. In this invention  optimization is performed only on the fourth stage of moving blades of the low pressure module and the preceding three stages are provided with parallel sided (cylindrical blades). Optimization is done to minimize secondary flow losses  enhance structural rigidity  thermodynamic performance and achieve tuned resonant frequencies.

US Patent no. 5211703 filed on Oct 24  1990 titled “Stationary blade design for L-OC row” discloses an optimized stationary blade of a steam turbine having a rotor and an inner cylinder for mounting the stationary blade in a row with plural identical stationary blades wherein the stagger angle of stationary blades ranges from about 42 degrees at the distal end to about 52 degrees at the proximal end. In this invention  optimization is done on stationary blades to reduce secondary flow losses and to achieve an optimized stress distribution  structural stiffness and tuned resonant frequencies.

US Patent Publication no. 2010 filed on Sep 8  2008 titled “Steam turbine rotating blade for a low pressure section of a steam turbine engine” discloses a rotating blade including an airfoil section  root section and tip section wherein the root section is attached to one end of the airfoil section and the tip section is attached to the opposite end of the airfoil section. A dovetail section projects from the root section  wherein the dovetail section includes a skewed axial entry dovetail. A shroud is integrally formed as part of the tip section. The blade includes an exit annulus area of about 2.83 m2. The shroud provided facilitates in improved blade stiffness and improved blade damping. The skewed axial entry dovetail helps in reducing stress concentration on blades and increase in exit annulus area facilitates in minimizing the loss of kinetic energy of steam.

Optimization of nozzles and blades is common in prior art but optimization of intermediate pressure module as a whole including optimization of rotating blades  stationary blades and solidity of blades (i.e.  no. of blades in each stage) is nowhere disclosed in the prior art. Moreover  Optimization of the intermediate pressure module at the above mentioned operational input data limiting to the range of predefined constraints is not at all performed. It is a challenging task for the profile developer to optimize the whole module meeting design constraints and considering different structural  thermal and aerodynamic parameters.

Therefore  there is a felt need for development of new series of blades and nozzles to overcome the drawbacks of the prior art and thereby producing a steam turbine intermediate pressure module with pressure ratio of 7 (Inlet Pressure/Exit Pressure) and having moderate reaction and high efficiency.

OBJECTS OF THE INVENTION:
An object of the present invention is to provide a steam turbine intermediate pressure module with high efficiency.

Another object of the present invention is to provide a steam turbine intermediate pressure module with moderate reaction twisted and tapered blades.

One more object of the present invention is to provide a compact steam turbine intermediate pressure module.

BRIEF DESCRIPTION OF THE DRAWINGS:
The invention will now be described with reference to the accompanying drawings in which:

Figure 1 illustrates a meridional view of conventional three stage impulse intermediate pressure module marked with a circle;

Figure 2 illustrates a sectional view of two adjacent blades depicting typical blade features;

Figure 3 illustrates sectional view of two adjacent nozzles depicting typical nozzle features;

Figure 4 illustrates a top sectional view of analytical model of hypothetical intermediate pressure module impulse moving blade and nozzle base profile obtained according to predefined operational input and set of predefined constraints;

Figure 5 illustrates a plot showing nozzles and blades across the stages of the intermediate pressure module of figure 4 on x-axis vs reaction on the nozzles and blades on y-axis;

Figure 6 illustrates a plot showing stages of the intermediate pressure module of figure 4 on x-axis vs efficiency across the stages on y-axis;

Figure 7 illustrates a meridional view of four stage reaction intermediate pressure module with axial length of the module on x-axis and radius on y-axis;

Figure 8 illustrates the output plots of a simulation run on the intermediate pressure module of figure 7 at operational input data;

Figure 8(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 7 on x-axis vs reaction on the nozzles and blades on y-axis;

Figure 8(b) illustrates a plot showing stages of the intermediate pressure module of figure 7 on x-axis vs efficiency across the stages on y-axis;

Figure 8(c) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 7 on x-axis vs radius at hub  mean and tip of the nozzles and blades on y-axis;

Figure 8(d) illustrates a plot showing stages of the intermediate pressure module of figure 7 on x-axis vs values of loading coefficient and flow coefficient on y-axis;

Figure 9 illustrates a plot showing stages of the intermediate pressure module of figure 7 on x-axis vs variation of flow coefficient on y-axis;

Figure 9(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding reaction on y-axis due to variation of flow coefficient of figure 9;

Figure 9(b) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding radius at hub  mean and tip of nozzles and blades on y-axis due to variation of flow coefficient of figure 9;

Figure 9(c) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding efficiency on y-axis due to variation of flow coefficient of figure 9;

Figure 10 illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 7 on x-axis vs variation of radius at hub  mean and tip of nozzles and blades on y-axis;

Figure 10(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding reaction on y-axis due to variation of radius at hub  mean and tip of nozzles and blades of figure 10;

Figure 10(b) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding efficiency on y-axis due to variation of radius at hub  mean and tip of nozzles and blades of figure 10;

Figure 10(c) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding loading coefficient and flow coefficient on y-axis due to variation of radius at hub  mean and tip of nozzles and blades of figure 10;

Figure 11 illustrates a plot showing stages of intermediate pressure module of figure 7 on x-axis vs variation of loading coefficient on y-axis;

Figure 11(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding reaction on y-axis due to variation of loading coefficient of figure 11;

Figure 11(b) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding efficiency on y-axis due to variation of loading coefficient of figure 11;

Figure 11(c) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding radius at hub  mean and tip of nozzles and blades due to variation of loading coefficient of figure 11;

Figure 12 illustrates a meridional view of five stage reaction intermediate pressure module with axial length of the module on x-axis and radius on y-axis;

Figure 13 illustrates the output plots of a simulation run on the intermediate pressure module of figure 12 at operational input data;

Figure 13(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 12 on x-axis vs reaction on the nozzles and blades on y-axis;

Figure 13(b) illustrates a plot showing stages of the intermediate pressure module of figure 12 on x-axis vs efficiency across the stages on y-axis;

Figure 13(c) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 12 on x-axis vs radius at hub  mean and tip of the nozzles and blades on y-axis;

Figure 13(d) illustrates a plot showing stages of the intermediate pressure module of figure 12 on x-axis vs values of loading coefficient and flow coefficient on y-axis;

Figure 14 illustrates a plot showing stages of the intermediate pressure module of figure 12 on x-axis vs variation of flow coefficient on y-axis;

Figure 14(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding reaction on y-axis due to variation of flow coefficient of figure 14;

Figure 14(b) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding radius at hub  mean and tip of nozzles and blades on y-axis due to variation of flow coefficient of figure 14;

Figure 14(c) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding efficiency on y-axis due to variation of flow coefficient of figure 14;
Figure 15 illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 12 on x-axis vs variation of radius at hub  mean and tip of nozzles and blades on y-axis;

Figure 15(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding reaction on y-axis due to variation of radius at hub  mean and tip of nozzles and blades of figure 15;

Figure 15(b) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding efficiency on y-axis due to variation of radius at hub  mean and tip of nozzles and blades of figure 15;

Figure 15(c) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding loading coefficient and flow coefficient on y-axis due to variation of radius at hub  mean and tip of nozzles and blades of figure 15;

Figure 16 illustrates a plot showing stages of intermediate pressure module of figure 12 on x-axis vs variation of loading coefficient on y-axis;

Figure 16(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding reaction on y-axis due to variation of loading coefficient of figure 16;

Figure 16(b) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding efficiency on y-axis due to variation of loading coefficient of figure 16;

Figure 16(c) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding radius at hub  mean and tip of nozzles and blades due to variation of loading coefficient of figure 16;
Figure 17(a) illustrates a comparative study of three stage impulse  four stage reaction and five stage reaction with stages on x-axis and total to total efficiencies on y-axis;

Figure 17(b) illustrates a comparative study of three stage impulse  four stage reaction and five stage reaction with stages on x-axis and total to static efficiencies on y-axis;

Figure 18 illustrates a comparative study of three stage impulse  four stage reaction and five stage reaction with nozzles and blades on x-axis and swirl on y-axis;

Figure 19(a) illustrates a meridional view of five stage reaction stair case design concept marked with a circle in accordance with the present invention;

Figure 19(b) illustrates a top view of the configuration of nozzles and moving blades along the axial length of rotor drum;

Figure 19(c) illustrates a schematic diagram of five stage reaction stair case design concept;

Figure 20 illustrates the output plots of a simulations run on the intermediate pressure module of figure 19(a) at operational input data;

Figure 20(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 19(a) on x-axis vs reaction on the nozzles and blades on y-axis;

Figure 20(b) illustrates a plot showing stages of the intermediate pressure module of figure 19(a) on x-axis vs efficiency across the stages on y-axis;

Figure 20(c) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 19(a) on x-axis vs radius at hub  mean and tip of the nozzles and blades on y-axis;

Figure 20(d) illustrates a plot showing stages of the intermediate pressure module of figure 19(a) on x-axis vs values of loading coefficient and flow coefficient on y-axis;

Figure 21 illustrates a comparative study of four stage  five stage and six stage reaction stair case design concept with stages on x-axis and total to total efficiencies on y-axis;

Figure 22 illustrates a comparative study of four stage  five stage and six stage reaction stair case design concept with stages on x-axis and total to static efficiencies on y-axis;

Figure 23 illustrates an isometric view of first stage tapered and twisted blade of figure 19(a);

Figure 23(a) illustrates a front view of a first stage tapered and twisted blade of figure 23;

Figure 23(b) illustrates a side view looking from C of figure 23(a);

Figure 23(c) illustrates a side view looking from D of figure 23(a);

Figure 23(d) illustrates a top view looking from A of figure 23(a);

Figure 24 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 23(a);

Figure 25 illustrates an isometric view of first stage nozzle of figure 19(a);

Figure 25(a) illustrates a front view of a first stage nozzle of figure 25;

Figure 25(b) illustrates a side view looking from C of figure 25(a);

Figure 25(c) illustrates a side view looking from D of figure 25(a);

Figure 25(d) illustrates a top view looking from A of figure 25(a);

Figure 26 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 25(a);

Figure 27 illustrates an isometric view of second stage tapered and twisted blade of figure 19(a);

Figure 27(a) illustrates a front view of a second stage tapered and twisted blade of figure 27;

Figure 27(b) illustrates a side view looking from C of figure 27(a);

Figure 27(c) illustrates a side view looking from D of figure 27(a);

Figure 27(d) illustrates a top view looking from A of figure 27(a);

Figure 28 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 27(a);

Figure 29 illustrates an isometric view of second stage nozzle of figure 19(a);

Figure 29(a) illustrates a front view of a second stage nozzle of figure 29;

Figure 29(b) illustrates a side view looking from C of figure 29(a);

Figure 29(c) illustrates a side view looking from D of figure 29(a);

Figure 29(d) illustrates a top view looking from A of figure 29(a);

Figure 30 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 29(a);

Figure 31 illustrates an isometric view of third stage tapered and twisted blade of figure 19(a);

Figure 31(a) illustrates a front view of a third stage tapered and twisted blade of figure 31;

Figure 31(b) illustrates a side view looking from C of figure 31(a);

Figure 31(c) illustrates a side view looking from D of figure 31(a);

Figure 31(d) illustrates a top view looking from A of figure 31(a);

Figure 32 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 31(a);

Figure 33 illustrates an isometric view of third stage nozzle of figure 19;

Figure 33(a) illustrates a front view of a third stage nozzle of figure 33;

Figure 33(b) illustrates a side view looking from C of figure 33(a);

Figure 33(c) illustrates a side view looking from D of figure 33(a);

Figure 33(d) illustrates a top view looking from A of figure 33(a);

Figure 34 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 33(a);

Figure 35 illustrates an isometric view of fourth stage tapered and twisted blade of figure 19(a);

Figure 35(a) illustrates a front view of a fourth stage tapered and twisted blade of figure 35;

Figure 35(b) illustrates a side view looking from C of figure 35(a);

Figure 35(c) illustrates a side view looking from D of figure 35(a);

Figure 35(d) illustrates a top view looking from A of figure 35(a);

Figure 36 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 35(a);

Figure 37 illustrates an isometric view of fourth stage nozzle of figure 19(a);

Figure 37(a) illustrates a front view of a fourth stage nozzle of figure 37;

Figure 37(b) illustrates a side view looking from C of figure 37(a);

Figure 37(c) illustrates a side view looking from D of figure 37(a);

Figure 37(d) illustrates a top view looking from A of figure 37(a);

Figure 38 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 37(a);

Figure 39 illustrates an isometric view of fifth stage tapered and twisted blade of figure 19(a);

Figure 39(a) illustrates a front view of a fifth stage tapered and twisted blade of figure 39;

Figure 39(b) illustrates a side view looking from C of figure 39(a);

Figure 39(c) illustrates a side view looking from D of figure 39(a);

Figure 39(d) illustrates a top view looking from A of figure 39(a);

Figure 40 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 39(a);

Figure 41 illustrates an isometric view of fifth stage nozzle of figure 19(a);

Figure 41(a) illustrates a front view of a fifth stage nozzle of figure 41;

Figure 41(b) illustrates a side view looking from C of figure 41(a);

Figure 41(c) illustrates a side view looking from D of figure 41(a);

Figure 41(d) illustrates a top view looking from A of figure 41(a); and

Figure 42 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 41(a).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
Figure 7 illustrates a meridional view of four stage reaction intermediate pressure module with axial length of the module on x-axis and radius on y-axis.

Figure 8 illustrates the output plots of a simulation run on the intermediate pressure module of figure 7 at operational input data.

Figure 8(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 7 on x-axis vs reaction on the nozzles and blades on y-axis.

Figure 8(b) illustrates a plot showing stages of the intermediate pressure module of figure 7 on x-axis vs efficiency across the stages on y-axis.

Figure 8(c) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 7 on x-axis vs radius at hub  mean and tip of the nozzles and blades on y-axis.

Figure 8(d) illustrates a plot showing stages of the intermediate pressure module of figure 7 on x-axis vs values of loading coefficient and flow coefficient on y-axis.

Figure 9 illustrates a plot showing stages of the intermediate pressure module of figure 7 on x-axis vs variation of flow coefficient on y-axis.

Figure 9(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding reaction on y-axis due to variation of flow coefficient of figure 9.

Figure 9(b) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding radius at hub  mean and tip of nozzles and blades on y-axis due to variation of flow coefficient of figure 9.

Figure 9(c) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding efficiency on y-axis due to variation of flow coefficient of figure 9.

Figure 10 illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 7 on x-axis vs variation of radius at hub  mean and tip of nozzles and blades on y-axis.

Figure 10(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding reaction on y-axis due to variation of radius at hub  mean and tip of nozzles and blades of figure 10.

Figure 10(b) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding efficiency on y-axis due to variation of radius at hub  mean and tip of nozzles and blades of figure 10.

Figure 10(c) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding loading coefficient and flow coefficient on y-axis due to variation of radius at hub  mean and tip of nozzles and blades of figure 10.

Figure 11 illustrates a plot showing stages of intermediate pressure module of figure 7 on x-axis vs variation of loading coefficient on y-axis.

Figure 11(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding reaction on y-axis due to variation of loading coefficient of figure 11.

Figure 11(b) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding efficiency on y-axis due to variation of loading coefficient of figure 11.

Figure 11(c) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding radius at hub  mean and tip of nozzles and blades due to variation of loading coefficient of figure 11.

Figure 12 illustrates a meridional view of five stage reaction intermediate pressure module with axial length of the module on x-axis and radius on y-axis.

Figure 13 illustrates the output plots of a simulation run on the intermediate pressure module of figure 12 at operational input data.

Figure 13(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 12 on x-axis vs reaction on the nozzles and blades on y-axis.

Figure 13(b) illustrates a plot showing stages of the intermediate pressure module of figure 12 on x-axis vs efficiency across the stages on y-axis.

Figure 13(c) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 12 on x-axis vs radius at hub  mean and tip of the nozzles and blades on y-axis.

Figure 13(d) illustrates a plot showing stages of the intermediate pressure module of figure 12 on x-axis vs values of loading coefficient and flow coefficient on y-axis.

Figure 14 illustrates a plot showing stages of the intermediate pressure module of figure 12 on x-axis vs variation of flow coefficient on y-axis.

Figure 14(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding reaction on y-axis due to variation of flow coefficient of figure 14.

Figure 14(b) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding radius at hub  mean and tip of nozzles and blades on y-axis due to variation of flow coefficient of figure 14.

Figure 14(c) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding efficiency on y-axis due to variation of flow coefficient of figure 14.

Figure 15 illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 12 on x-axis vs variation of radius at hub  mean and tip of nozzles and blades on y-axis.

Figure 15(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding reaction on y-axis due to variation of radius at hub  mean and tip of nozzles and blades of figure 15.

Figure 15(b) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding efficiency on y-axis due to variation of radius at hub  mean and tip of nozzles and blades of figure 15.

Figure 15(c) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding loading coefficient and flow coefficient on y-axis due to variation of radius at hub  mean and tip of nozzles and blades of figure 15.

Figure 16 illustrates a plot showing stages of intermediate pressure module of figure 12 on x-axis vs variation of loading coefficient on y-axis.

Figure 16(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding reaction on y-axis due to variation of loading coefficient of figure 16.

Figure 16(b) illustrates a plot showing stages of the intermediate pressure module on x-axis vs corresponding efficiency on y-axis due to variation of loading coefficient of figure 16.

Figure 16(c) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module on x-axis vs corresponding radius at hub  mean and tip of nozzles and blades due to variation of loading coefficient of figure 16.

In accordance with the present invention  the optimization is performed in a phase wise manner by considering all the possibilities. Simulations are run on four stage reaction module and five stage reaction module by varying the parameters of flow coefficient  hub radius  loading coefficient and exit swirl keeping the design requirement of maximum efficiency. Exit swirl is varied indirectly by varying the exit pressure.

Figure 17(a) illustrates a comparative study of three stage impulse  four stage reaction and five stage reaction with stages on x-axis and total to total efficiencies on y-axis.

Figure 17(b) illustrates a comparative study of three stage impulse  four stage reaction and five stage reaction with stages on x-axis and total to static efficiencies on y-axis.

Figure 18 illustrates a comparative study of three stage impulse  four stage reaction and five stage reaction with nozzles and blades on x-axis and swirl on y-axis.

It is evident from the plots 17(a) and 17(b) that total to total and total to static efficiencies are higher for the five stage reaction module when compared to three stage impulse and four stage reaction modules. Efficiencies will be high for six stage reaction module when compared to five stage reaction module but the option of six stages is ruled out due to space constraints.

It is evident from plot 18 that exit swirl is maintained between the specified constraint of -15 deg to + 15 deg in all the iterations.

It is also evident from all the plots 8(c)  9(b)  10  11(c)  13(c)  14(b)  15  16(c) that the radius of the hub at the first stage of intermediate pressure module is about 400mm. The radius of the hub at the inlet of intermediate pressure module should have less variation when compared to the radius of hub at the exit of high pressure module otherwise flow phenomenon will get distorted. The new design concern now is to find out a mechanism to achieve the inlet hub radius of the intermediate pressure module inline to the exit hub radius of the high pressure module without compromising on efficiency.

Figure 19(a) illustrates a meridional view of five stage reaction stair case design concept marked with a circle in accordance with the present invention.

Figure 19(b) illustrates a top view of the configuration of nozzles and moving blades along the axial length of rotor drum.

Figure 19(c) illustrates a schematic diagram of five stage stair case design concept;

Figure 20 illustrates the output plots of a simulations run on the intermediate pressure module of figure 19(a) at operational input data.

Figure 20(a) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 19(a) on x-axis vs reaction on the nozzles and blades on y-axis.

Figure 20(b) illustrates a plot showing stages of the intermediate pressure module of figure 19(a) on x-axis vs efficiency across the stages on y-axis.

Figure 20(c) illustrates a plot showing nozzles and blades across the stages of intermediate pressure module of figure 19(a) on x-axis vs radius at hub  mean and tip of the nozzles and blades on y-axis.

Figure 20(d) illustrates a plot showing stages of the intermediate pressure module of figure 19(a) on x-axis vs values of loading coefficient and flow coefficient on y-axis.

Figure 21 illustrates a comparative study of four stage  five stage and six stage reaction stair case design concept with stages on x-axis and total to total efficiencies on y-axis.

Figure 22 illustrates a comparative study of four stage  five stage and six stage reaction stair case design concept with stages on x-axis and total to static efficiencies on y-axis.

It is evident from the figure 20(a) that all the blades across five stages of the module are having a moderate mean reaction of 35%.

It can be concluded from the figures 21 and 22 that the efficiency of six stage stair case design over the initial four stages is less than the five stage stair case design. So  five stage stair case design is finally selected after the optimization.

Referring to Fig. 19(a)  there is provided a meridional view of five stage stair case design comprising a rotor drum 210  a plurality of first stage tapered and twisted moving blades 220  a plurality of second stage twisted and tapered moving blades 230  a plurality of third stage twisted and tapered moving blades 240  a plurality of fourth stage twisted and tapered moving blades 250  a plurality of fifth stage twisted and tapered moving blades 260  a plurality of first stage nozzles 270  a plurality of second stage nozzles 280  a plurality of third stage nozzles 290  a plurality of fourth stage nozzles 300  plurality of fifth stage nozzles 310 and casing 320.

The moving blades 220  230  240  250 and 260 are mounted on the rotor drum 210 and projects outward toward the casing 320. The nozzles 270  280  290  300 and 310 are enclosed in nozzle diaphragms (270(a)  280(a)  290(a)  300(a) and 310(a)) which in turn are mounted in the casing 320 of the turbine. The configuration of the moving blades (220  230  240  250 and 260) and the nozzles (270  280  290  300 and 310) is in such a way that they are placed alternative to each other in opposite direction along the axial length of the rotor drum 210 as shown in figure 19(b). The rotor drum 210 diameter is increased in a step wise manner at each stage as shown in figure 19(c).

Figure 23 illustrates an isometric view of first stage tapered and twisted blade of figure 19(a).

Figure 23(a) illustrates a front view of a first stage tapered and twisted blade of figure 23.

Figure 23(b) illustrates a side view looking from C of figure 23(a).

Figure 23(c) illustrates a side view looking from D of figure 23(a).

Figure 23(d) illustrates a top view looking from A of figure 23(a).

Referring to figures 23  23(a)  23(b)  23(c) and 23(d)  the first stage tapered and twisted moving blade 220 includes a convex suction side 221  a concave pressure side 222  a root portion 223  a platform portion 224  an airfoil portion 225  a tip portion 226  a leading edge 227  a trailing edge 228 and a shroud 229.

The shroud 229 is formed integrally at the tip portion 226 of the first stage tapered and twisted moving blade 220. The shroud 229 is of tapered wedge shape with thickness of 7.69mm on the side of leading edge 227 and thickness of 5mm on the side of trailing edge 228 and is indicated by reference numerals T1 and T2 respectively as shown in figure 23(a). The length and width of the shroud is 30mm and 26mm and is indicated by reference numerals X1 and Y1 respectively as shown in the figure 23(d).

The convex suction side 221 and the concave pressure side 222 of the first stage tapered and twisted moving blade 220 are joined at the extreme ends by means of leading edge 227 and trailing edge 228. The length of the blade 220 from the base of the root portion 223 to the top of the shroud 229 is of 80 mm and is indicated by a reference numeral Y2 as shown in figure 23(a). A flare of 10-15 degrees with respect to horizontal is provided at the tip portion 226 of the blade 220 and is indicated by reference numeral ?1 as shown in the figure 23(a). The root portion 223 of the blade 220 is of T shape with a skewed axial entry of 26 degrees and is indicated by a reference numeral ?2 as shown in the figure 23(d).

Figure 24 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 23(a). The parameters that define the geometry of first stage tapered and twisted moving blades 220 after the optimization is performed were tabulated in the Table 3 below.
Table 3
Parameter Hub Section(H-H) Mean Section(M-M) Tip section(T-T)
Chord 35 mm 35 mm 35 mm
Inlet Angle 43 deg 35.73 deg 26.84 deg
Exit Angle -80.44 deg -79.30 deg -77.05deg
Leading edge radius 2 mm 1.75 mm 1.5 mm
Stagger Angle -31.73 deg -33.89 deg -37.41 deg
Trailing edge radius 0.5 mm 0.5 mm 0.5 mm
Unguided turning 18.98 deg 19.76 deg 20.46 deg
Angle of Attack -31.73 deg -33.89 deg -37.41 deg
Area 0.00030676 m2 0.000255482 m2 0.000224705 m2
Axial chord(width) 29.76 mm 29.05 mm 27.79 mm
Camber 123.446 deg 115.042 deg 103.903 deg
Maximum Thickness 7.8256 mm 7.832 mm 7.733 mm
Pitch/Chord 0.739 0.789 0.836
Radius at CG 350 mm 371.274 mm 391.23 mm
Solidity 1.36 1.28 1.20
Throat/Pitch 0.368 0.369 0.365
Tmax/Chord 0.223 0.223 0.22

All the angles and distances in the table 3 are measured along the meridional direction.

Figure 25 illustrates an isometric view of first stage nozzle of figure 19(a).

Figure 25(a) illustrates a front view of a first stage nozzle of figure 25.

Figure 25(b) illustrates a side view looking from C of figure 25(a).

Figure 25(c) illustrates a side view looking from D of figure 25(a).

Figure 25(d) illustrates a top view looking from A of figure 25(a).

Referring to figures 25  25(a)  25(b)  25(c) and 25(d)  the first stage nozzle 270 includes a convex suction side 271  a concave pressure side 272  a leading edge 277 and a trailing edge 278. The first stage nozzle 270 is a cylindrical blade.

The convex suction side 271 and the concave pressure side 272 of the first stage nozzle 270 are joined at the extreme ends by means of leading edge 277 and trailing edge 278. The length of the nozzle 270 is of 40.72 mm and is indicated by a reference numeral Y3 as shown in figure 25(a).

Figure 26 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 25(a). The parameters that define the geometry of first stage nozzles 270 after the optimization is performed were tabulated in the Table 4below. As the first stage nozzle is cylindrical blade  all the parameters will be same at Hub  Mean and Tip.
Table 4
Parameter Hub Section(H-H)
Chord 43 mm
Inlet Angle 0 deg
Exit Angle 80.59 deg
Leading edge radius 3.5 mm
Stagger Angle 55 deg
Trailing edge radius 0.4 mm
Unguided turning 16 deg
Angle of Attack 55 deg
Area 0.0002377 m2
Axial chord(width) 24.66 mm
Camber -80.59 deg
Maximum Thickness 8.1844 mm
Pitch/Chord 0.763
Radius at CG 350 mm
Solidity 1.360
Throat/Pitch 0.2099
Tmax/Chord 0.1903337

All the angles and distances in the table 4 are measured along the meridional direction.

Figure 27 illustrates an isometric view of second stage tapered and twisted blade of figure 19(a).

Figure 27(a) illustrates a front view of a second stage tapered and twisted blade of figure 27.

Figure 27(b) illustrates a side view looking from C of figure 27(a).

Figure 27(c) illustrates a side view looking from D of figure 27(a).

Figure 27(d) illustrates a top view looking from A of figure 27(a).

Referring to figures 27  27(a)  27(b)  27(c) and 27(d)  the second stage tapered and twisted moving blade 230 includes a convex suction side 231  a concave pressure side 232  a root portion 233  a platform portion 234  an airfoil portion 235  a tip portion 236  a leading edge 237  a trailing edge 238 and a shroud 239.

The shroud 239 is formed integrally at the tip portion 236 of the second stage tapered and twisted moving blade 230. The shroud 239 is of tapered wedge shape with thickness of 8.52 mm on the side of leading edge 237 and thickness of 5mm on the side of trailing edge 238 and is indicated by reference numerals T3 and T4 respectively as shown in figure 27(a). The length and width of the shroud is 32mm and 26mm and is indicated by reference numerals X2 and Y4 respectively as shown in the figure 27(d).

The convex suction side 231 and the concave pressure side 232 of the second stage tapered and twisted moving blade 230 are joined at the extreme ends by means of leading edge 237 and trailing edge 238. The length of the blade 230 from the base of the root portion 233 to the top of the shroud 239 is of 91.42 mm and is indicated by a reference numeral Y5 as shown in figure 27(a). A flare of 10-15 degrees with respect to horizontal is provided at the tip portion 236 of the blade 230 and is indicated by reference numeral ?3 as shown in the figure 27(a). The root portion 233 of the blade 230 is of T shape with a skewed axial entry of 20 degrees and is indicated by a reference numeral ?4 as shown in the figure 27(d).

Figure 28 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 27(a). The parameters that define the geometry of second stage tapered and twisted moving blades 230 after the optimization is performed were tabulated in the Table 5 below.
Table 5
Parameter Hub Section(H-H) Mean Section(M-M) Tip section(T-T)
Chord 35 mm 35 mm 35 mm
Inlet Angle 45 deg 37.66 deg 30.649 deg
Exit Angle -77.10 deg -74.33 deg -70.32 deg
Leading edge radius 2 mm 2 mm 1.5 mm
Stagger Angle -32.49 deg -34.786 deg -36.99 deg
Trailing edge radius 0.4 mm 0.4 mm 0.4 mm
Unguided turning 10.07 deg 10 deg 9.54 deg
Angle of Attack -32.49 deg -34.786 deg -36.99 deg
Area 0.000372 m2 0.000308 m2 0.000212 m2
Axial chord(width) 29.519 mm 28.744 mm 27.95 mm
Camber 122.17 deg 112 deg 100.96 deg
Maximum Thickness 8.0 mm 7.78 mm 7.02 mm
Pitch/Chord 0.74 0.80 0.86
Radius at CG 355 mm 382.17 mm 407.317 mm
Solidity 1.363 1.258 1.17
Throat/Pitch 0.193 0.252 0.352
Tmax/Chord 0.228 0.222 0.200

All the angles and distances in the table 5 are measured along the meridional direction.

Figure 29 illustrates an isometric view of second stage nozzle of figure 19(a).

Figure 29(a) illustrates a front view of a second stage nozzle of figure 29.

Figure 29(b) illustrates a side view looking from C of figure 29(a).

Figure 29(c) illustrates a side view looking from D of figure 29(a).

Figure 29(d) illustrates a top view looking from A of figure 29(a).

Referring to figures 29  29(a)  29(b)  29(c) and 29(d)  the second stage nozzle 280 includes a convex suction side 281  a concave pressure side 282  a leading edge 287 and a trailing edge 288. The second stage nozzle 280 is a cylindrical blade.

The convex suction side 281 and the concave pressure side 282 of the second stage nozzle 280 are joined at the extreme ends by means of leading edge 287 and trailing edge 288. The length of the nozzle 280 is of 49.68 mm and is indicated by a reference numeral Y6 as shown in figure 29(a).

Figure 30 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 29(a). The parameters that define the geometry of second stage nozzles 280 after the optimization is performed were tabulated in the Table 6 below. As the second stage nozzle is cylindrical blade  all the parameters will be same at Hub  Mean and Tip.

Table 6
Parameter Hub Section(H-H)
Chord 44 mm
Inlet Angle 10 deg
Exit Angle 81.07deg
Leading edge radius 3.5 mm
Stagger Angle 58 deg
Trailing edge radius 0.4 mm
Unguided turning 16 deg
Angle of Attack 58 deg
Area 0.0002255 m2
Axial chord(width) 23.316 mm
Camber -71.07 deg
Maximum Thickness 7.96 mm
Pitch/Chord 0.779
Radius at CG 355 mm
Solidity 1.336
Throat/Pitch 0.20697
Tmax/Chord 0.1810

All the angles and distances in the table 6 are measured along the meridional direction.

Figure 31 illustrates an isometric view of third stage tapered and twisted blade of figure 19(a);

Figure 31(a) illustrates a front view of a third stage tapered and twisted blade of figure 31;

Figure 31(b) illustrates a side view looking from C of figure 31(a);

Figure 31(c) illustrates a side view looking from D of figure 31(a);

Figure 31(d) illustrates a top view looking from A of figure 31(a);

Referring to figures 31  31(a)  31(b)  31(c) and 31(d)  the third stage tapered and twisted moving blade 240 includes a convex suction side 241  a concave pressure side 242  a root portion 243  a platform portion 244  an airfoil portion 245  a tip portion 246  a leading edge 247  a trailing edge 248 and a shroud 249.

The shroud 249 is formed integrally at the tip portion 246 of the third stage tapered and twisted moving blade 240. The shroud 249 is of tapered wedge shape with thickness of 8.52 mm on the side of leading edge 247 and thickness of 5mm on the side of trailing edge 248 and is indicated by reference numerals T5 and T6 respectively as shown in figure 31(a). The length and width of the shroud is 35.5mm and 31mm and is indicated by reference numerals X3 and Y7 respectively as shown in the figure 31(d).

The convex suction side 241 and the concave pressure side 242 of the third stage tapered and twisted moving blade 240 are joined at the extreme ends by means of leading edge 247 and trailing edge 248. The length of the blade 240 from the base of the root portion 243 to the top of the shroud 249 is of 118.8 mm and is indicated by a reference numeral Y8 as shown in figure 31(a). A flare of 10-15 degrees with respect to horizontal is provided at the tip portion 246 of the blade 240 and is indicated by reference numeral ?5 as shown in the figure 31(a). The root portion 243 of the blade 240 is of T shape with a skewed axial entry of 20 degrees and is indicated by a reference numeral ?6 as shown in the figure 31(d).

Figure 32 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 31(a). The parameters that define the geometry of third stage tapered and twisted moving blades 240 after the optimization is performed were tabulated in the Table 7 below.

Table 7
Parameter Hub Section(H-H) Mean Section(M-M) Tip section(T-T)
Chord 40 mm 40 mm 40 mm
Inlet Angle 45.314 deg 30.073 deg 17.745 deg
Exit Angle -71.6561 deg -71.49 deg -71.35 deg
Leading edge radius 1.5 mm 1.25 mm 1 mm
Stagger Angle -31.01 deg -36.46 deg -41.69 deg
Trailing edge radius 0.4 mm 0.4 mm 0.4 mm
Unguided turning 9.02 deg 9.04 deg 9.05 deg
Angle of Attack -31.0133 deg -36.4632 deg -41.69 deg
Area 0.0003377 m2 0.0002814 m2 0.00023844 m2
Axial chord(width) 34.28 mm 32.16 mm 29.86 mm
Camber 116.97 deg 101.56 deg 89.0998 deg
Maximum Thickness 9.078 mm 8.659 mm 7.930 mm
Pitch/Chord 0.6353 0.704 0.76
Radius at CG 360 mm 395.83mm 428.45 mm
Solidity 1.58 1.43 1.31
Throat/Pitch 0.2843 0.290 0.296
Tmax/Chord 0.226 0.216 0.198

All the angles and distances in the table 7 are measured along the meridional direction.

Figure 33 illustrates an isometric view of third stage nozzle of figure 19.

Figure 33(a) illustrates a front view of a third stage nozzle of figure 33.

Figure 33(b) illustrates a side view looking from C of figure 33(a).

Figure 33(c) illustrates a side view looking from D of figure 33(a).

Figure 33(d) illustrates a top view looking from A of figure 33(a).

Referring to figures 33  33(a)  33(b)  33(c) and 33(d)  the third stage nozzle 290 includes a convex suction side 291  a concave pressure side 292  a leading edge 297 and a trailing edge 298. The third stage nozzle 290 is a cylindrical blade.

The convex suction side 291 and the concave pressure side 292 of the third stage nozzle 290 are joined at the extreme ends by means of leading edge 297 and trailing edge 298. The length of the nozzle 290 is of 65.8 mm and is indicated by a reference numeral Y9 as shown in figure 33(a).

Figure 34 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 33(a). The parameters that define the geometry of third stage nozzles 290 after the optimization is performed were tabulated in the Table 8 below. As the third stage nozzle is cylindrical blade  all the parameters will be same at Hub  Mean and Tip.
Table 8
Parameter Hub Section(H-H)
Chord 61 mm
Inlet Angle 0 deg
Exit Angle 76.70 deg
Leading edge radius 3 mm
Stagger Angle 57 deg
Trailing edge radius 0.5 mm
Unguided turning 8 deg
Angle of Attack 57 deg
Area 0.00042369 m2
Axial chord(width) 33.2228 mm
Camber -76.70 deg
Maximum Thickness 10.9699 mm
Pitch/Chord 0.7270
Radius at CG 360 mm
Solidity 1.411
Throat/Pitch 0.207875
Tmax/Chord 0.179834

All the angles and distances in the table 8 are measured along the meridional direction.

Figure 35 illustrates an isometric view of fourth stage tapered and twisted blade of figure 19(a).

Figure 35(a) illustrates a front view of a fourth stage tapered and twisted blade of figure 35.

Figure 35(b) illustrates a side view looking from C of figure 35(a).

Figure 35(c) illustrates a side view looking from D of figure 35(a).

Figure 35(d) illustrates a top view looking from A of figure 35(a).

Referring to figures 35  35(a)  35(b)  35(c) and 35(d)  the fourth stage tapered and twisted moving blade 250 includes a convex suction side 251  a concave pressure side 252  a root portion 253  a platform portion 254  an airfoil portion 255  a tip portion 256  a leading edge 257  a trailing edge 258 and a shroud 259.

The shroud 259 is formed integrally at the tip portion 256 of the fourth stage tapered and twisted moving blade 250. The shroud 259 is of tapered wedge shape with thickness of 8.98 mm on the side of leading edge 257 and thickness of 5mm on the side of trailing edge 258 and is indicated by reference numerals T7 and T8 respectively as shown in figure 35(a). The length and width of the shroud is 26mm and 33mm and is indicated by reference numerals X4 and Y10 respectively as shown in the figure 35(d).

The convex suction side 251 and the concave pressure side 252 of the fourth stage tapered and twisted moving blade 250 are joined at the extreme ends by means of leading edge 257 and trailing edge 258. The length of the blade 250 from the base of the root portion 253 to the top of the shroud 259 is of 144.16 mm and is indicated by a reference numeral Y11 as shown in figure 35(a). A flare of 10-15 degrees with respect to horizontal is provided at the tip portion 256 of the blade 250 and is indicated by reference numeral ?7 as shown in the figure 35(a). The root portion 253 of the blade 250 is of T shape with a skewed axial entry of 27 degrees and is indicated by a reference numeral ?8 as shown in the figure 35(d).

Figure 36 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 35(a). The parameters that define the geometry of fourth stage tapered and twisted moving blades 250 after the optimization is performed were tabulated in the Table 9 below.
Table 9
Parameter Hub Section(H-H) Mean Section(M-M) Tip section(T-T)
Chord 43 mm 39 mm 40 mm
Inlet Angle 35.6337 deg 22.075 deg 8 deg
Exit Angle -71.24 deg -75.64 deg -79.85 deg
Leading edge radius 2 mm 1.5 mm 1 mm
Stagger Angle -29.95 deg -43.058 deg -55 deg
Trailing edge radius 0.4 mm 0.4 mm 0.4 mm
Unguided turning 10 deg 15 deg 20 deg
Angle of Attack -29.95 deg -43.058 deg -55 deg
Area 0.0003372 m2 0.0002273 m2 0.0001592 m2
Axial chord(width) 37.25 mm 28.49 mm 22.94 mm
Camber 106.875 deg 97.722 deg 87.8543 deg
Maximum Thickness 9.88 mm 7.39 mm 6.17 mm
Pitch/Chord 0.6130 0.7739 0.8394
Radius at CG 365 mm 414.36 mm 457.84 mm
Solidity 1.64 1.30 1.20
Throat/Pitch 0.299 0.277 0.257
Tmax/Chord 0.229 0.189 0.154

All the angles and distances in the table 9 are measured along the meridional direction.

Figure 37 illustrates an isometric view of fourth stage nozzle of figure 19(a).

Figure 37(a) illustrates a front view of a fourth stage nozzle of figure 37.

Figure 37(b) illustrates a side view looking from C of figure 37(a).

Figure 37(c) illustrates a side view looking from D of figure 37(a).

Figure 37(d) illustrates a top view looking from A of figure 37(a).

Referring to figures 37  37(a)  37(b)  37(c) and 37(d)  the fourth stage nozzle 300 includes a convex suction side 301  a concave pressure side 302  a leading edge 307 and a trailing edge 308. The fourth stage nozzle 300 is a tapered and twisted blade.

The convex suction side 301 and the concave pressure side 302 of the fourth stage nozzle 300 are joined at the extreme ends by means of leading edge 307 and trailing edge 308. The length of the nozzle 300 is of 87.4 mm and is indicated by a reference numeral Y12 as shown in figure 37(a).

Figure 38 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 37(a). The parameters that define the geometry of fourth stage nozzles 301 after the optimization is performed were tabulated in the Table 10 below.

Table 10
Parameter Hub Section(H-H) Mean Section(M-M) Tip section(T-T)
Chord 52.45 mm 58.87 mm 64.99 mm
Inlet Angle 0 deg 2.77 deg 5.05 deg
Exit Angle 76.65 deg 78.38 deg 79.97 deg
Leading edge radius 4 mm 4 mm 4 mm
Stagger Angle 50 deg 52.52 deg 54.97 deg
Trailing edge radius 0.5 mm 0.5 mm 0.5 mm
Unguided turning 14 deg 14.04 deg 14.09 deg
Angle of Attack 50 deg 52.52 deg 54.97 deg
Area 0.000427 m2 0.000525 m2 0.000620 m2
Axial chord(width) 33.714 mm 35.821 mm 37.30 mm
Camber -76.65 deg -75.60 deg -74.91 deg
Maximum Thickness 11.04 mm 12.46 mm 13.27 mm
Pitch/Chord 0.809 0.814 0.813
Radius at CG 365 mm 408.24 mm 447.20 mm
Solidity 1.27 1.26 1.26
Throat/Pitch 0.243 0.216 0.192
Tmax/Chord 0.210 0.211 0.204

All the angles and distances in the table 10 are measured along the meridional direction.

Figure 39 illustrates an isometric view of fifth stage tapered and twisted blade of figure 19(a).

Figure 39(a) illustrates a front view of a fifth stage tapered and twisted blade of figure 39.

Figure 39(b) illustrates a side view looking from C of figure 39(a).

Figure 39(c) illustrates a side view looking from D of figure 39(a).

Figure 39(d) illustrates a top view looking from A of figure 39(a).

Referring to figures 39  39(a)  39(b)  39(c) and 39(d)  the fifth stage tapered and twisted moving blade 260 includes a convex suction side 261  a concave pressure side 262  a root portion 263  a platform portion 264  an airfoil portion 265  a tip portion 266  a leading edge 267  a trailing edge 268 and a shroud 269.

The shroud 269 is formed integrally at the tip portion 266 of the fifth stage tapered and twisted moving blade 260. The shroud 269 is of tapered wedge shape with thickness of 10.22 mm on the side of leading edge 267 and thickness of 5mm on the side of trailing edge 268 and is indicated by reference numerals T9 and T10 respectively as shown in figure 39(a). The length and width of the shroud is 28.9mm and 38.4mm and is indicated by reference numerals X5 and Y13 respectively as shown in the figure 39(d).

The convex suction side 261 and the concave pressure side 262 of the fifth stage tapered and twisted moving blade 260 are joined at the extreme ends by means of leading edge 267 and trailing edge 268. The length of the blade 260 from the base of the root portion 263 to the top of the shroud 269 is of 178.81 mm and is indicated by a reference numeral Y14 as shown in figure 39(a). A flare of 10-15 degrees with respect to horizontal is provided at the tip portion 266 of the blade 260 and is indicated by reference numeral ?9 as shown in the figure 39(a). The root portion 263 of the blade 260 is of T shape with a skewed axial entry of 28degrees and is indicated by a reference numeral ?10 as shown in the figure 39(d).

Figure 40 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 39(a). The parameters that define the geometry of fifth stage tapered and twisted moving blade 260 after the optimization is performed were tabulated in the Table 11 below.

Table 11
Parameter Hub Section(H-H) Mean Section(M-M) Tip section(T-T)
Chord 50 mm 46.32 mm 49.2 mm
Inlet Angle 33.0307 deg 7.29 deg -16.78 deg
Exit Angle -73.11 deg -73.08 deg -72.54 deg
Leading edge radius 2 mm 1.75 mm 1.25 mm
Stagger Angle -27 deg -49.64 deg -59.03 deg
Trailing edge radius 0.5 mm 0.5 mm 0.5 mm
Unguided turning 10.9653 deg 11.188 deg 11.369 deg
Angle of Attack -27deg -49.64 deg -59.03 deg
Area 0.000494 m2 0.000207 m2 0.000154 m2
Axial chord(width) 44.55 mm 29.99 mm 25.311 mm
Camber 106.15 deg 80.374 deg 55.75 deg
Maximum Thickness 11.96 mm 7.29 mm 4.81 mm
Pitch/Chord 0.561 0.721 0.774
Radius at CG 375 mm 442.53 mm 499.89 mm
Solidity 1.79 1.409 1.314
Throat/Pitch 0.294 0.311 0.325
Tmax/Chord 0.239 0.157 0.0979

All the angles and distances in the table 11 are measured along the meridional direction.

Figure 41 illustrates an isometric view of fifth stage nozzle of figure 19(a);

Figure 41(a) illustrates a front view of a fifth stage nozzle of figure 41.

Figure 41(b) illustrates a side view looking from C of figure 41(a).

Figure 41(c) illustrates a side view looking from D of figure 41(a).

Figure 41(d) illustrates a top view looking from A of figure 41(a).

Referring to figures 41  41(a)  41(b)  41(c) and 41(d)  the fifth stage nozzle 310 includes a convex suction side 311  a concave pressure side 312  a leading edge 317 and a trailing edge 318. The fifth stage nozzle 310 is a tapered and twisted blade.

The convex suction side 311 and the concave pressure side 312 of the fifth stage nozzle 310 are joined at the extreme ends by means of leading edge 317 and trailing edge 318. The length of the nozzle 310 is of 115.9 mm and is indicated by a reference numeral Y15 as shown in figure 41(a).

Figure 42 illustrates a top view of airfoil sections at Hub(H-H)  Mean(M-M) and Tip(T-T) of figure 41(a). The parameters that define the geometry of fifth stage nozzles 310 after the optimization is performed were tabulated in the Table 12 below.
Table 12
Parameter Hub Section(H-H) Mean Section(M-M) Tip section(T-T)
Chord 58.15 mm 67.36 mm 75 mm
Inlet Angle 5.01 deg 0.51 deg -5.44 deg
Exit Angle 73.71 deg 76.22 deg 78.15 deg
Leading edge radius 4 mm 4 mm 4 mm
Stagger Angle 50.94 deg 52.05 deg 52.99 deg
Trailing edge radius 0.5 mm 0.5 mm 0.5 mm
Unguided turning 9 deg 7.93deg 7.18 deg
Angle of Attack 50.94 deg 52.05 deg 52.99 deg
Area 0.0004515 m2 0.0005856 m2 0.0007229 m2
Axial chord(width) 36.64 mm 41.42 mm 45.13 mm
Camber -68.69 deg -75.70 deg -83.60 deg
Maximum Thickness 11.61 mm 13.06 mm 13.74 mm
Pitch/Chord 0.750 0.755 0.763
Radius at CG 375 mm 427.82 mm 474.05mm
Solidity 1.37 1.35 1.34
Throat/Pitch 0.258 0.221 0.189
Tmax/Chord 0.199 0.193 0.183

Although the invention has been described herein above with reference to the embodiments of the invention  the invention is not limited to the embodiments described herein above. It is to be understood that modifications and variations of the embodiments can be made without departing from the spirit and scope of the invention.

We claim:
1) A steam turbine intermediate pressure module with moderate reaction comprising:
a) a plurality of first stage  second stage  third stage  fourth stage and fifth stage tapered and twisted moving blades adapted to fit in rotor discs of the turbine  wherein the plurality of first stage tapered and twisted blades comprises an airfoil portion bound to a leading edge and a trailing edge forming a convex suction side and a concave pressure side  a root portion formed integrally of the airfoil portion at the proximal end of the rotor disc and a shroud formed integrally of the airfoil portion at the distal end of the rotor disc  said shroud having tapered wedge shape of length and breadth 30mm and 29mm respectively with maximum thickness of 7.69 mm on the leading edge and minimum thickness of 5 mm on the trailing edge  said root portion of the first stage blades is of skewed radial entry T-root type;

wherein the plurality of second stage tapered and twisted blades comprises an airfoil portion bound to a leading edge and a trailing edge forming a convex suction side and a concave pressure side  a root portion formed integrally of the airfoil portion at the proximal end of the rotor disc and a shroud formed integrally of the airfoil portion at the distal end of the rotor disc  said shroud having tapered wedge shape of length and breadth 32mm and 30mm respectively with maximum thickness of 8.52 mm on the leading edge and minimum thickness of 5 mm on the trailing edge  said root portion of the second stage blades is of skewed radial entry T-root type;

wherein the plurality of third stage tapered and twisted blades comprises an airfoil portion bound to a leading edge and a trailing edge forming a convex suction side and a concave pressure side  a root portion formed integrally of the airfoil portion at the proximal end of the rotor disc and a shroud formed integrally of the airfoil portion at the distal end of the rotor disc  said shroud having tapered wedge shape of length and breadth 35mm and31mm respectively with maximum thickness of 8.52 mm on the leading edge and minimum thickness of 5 mm on the trailing edge  said root portion of the third stage blades is of skewed radial entry T-root type;

wherein the plurality of fourth stage tapered and twisted blades comprises an airfoil portion bound to a leading edge and a trailing edge forming a convex suction side and a concave pressure side  a root portion formed integrally of the airfoil portion at the proximal end of the rotor disc and a shroud formed integrally of the airfoil portion at the distal end of the rotor disc  said shroud having tapered wedge shape of length and breadth 26mm and 33mm respectively with maximum thickness of 8.96 mm on the leading edge and minimum thickness of 5 mm on the trailing edge  said root portion of the fourth stage blades is of skewed radial entry T-root type; and

wherein the plurality of fifth stage tapered and twisted blades comprises an airfoil portion bound to a leading edge and a trailing edge forming a convex suction side and a concave pressure side  a root portion formed integrally of the airfoil portion at the proximal end of the rotor disc and a shroud formed integrally of the airfoil portion at the distal end of the rotor disc  said shroud having tapered wedge shape of length and breadth 29mm and 39mm respectively with maximum thickness of 10.22 mm on the leading edge and minimum thickness of 5 mm on the trailing edge  said root portion of the fifth stage blades is of skewed radial entry T-root type;

b) a plurality of first stage  second stage  third stage  fourth stage and fifth stage nozzles enclosed in nozzle diaphragms  said nozzle diaphragms in turn adapted to fit in the grooves provided alternatively to said moving blades in casing of said turbine.

2) A steam turbine intermediate pressure module with moderate reaction as claimed in claim 1  wherein the first  second and third stage nozzles are of cylindrical type and the fourth and fifth stage nozzles are of tapered and twisted type.

3) A steam turbine intermediate pressure module with moderate reaction as claimed in claim 1  wherein the geometry defining parameters of the first stage moving blades at hub  mean and tip sections are according to the following table:

Parameter Hub Section(H-H) Mean Section(M-M) Tip section(T-T)
Chord 35 mm 35 mm 35 mm
Inlet Angle 43 deg 35.73 deg 26.84 deg
Exit Angle -80.44 deg -79.30 deg -77.05deg
Leading edge radius 2 mm 1.75 mm 1.5 mm
Stagger Angle -31.73 deg -33.89 deg -37.41 deg
Trailing edge radius 0.5 mm 0.5 mm 0.5 mm
Unguided turning 18.98 deg 19.76 deg 20.46 deg
Angle of Attack -31.73 deg -33.89 deg -37.41 deg
Area 0.00030676 m2 0.000255482 m2 0.000224705 m2
Axial chord(width) 29.76 mm 29.05 mm 27.79 mm
Camber 123.446 deg 115.042 deg 103.903 deg
Maximum Thickness 7.8256 mm 7.832 mm 7.733 mm
Pitch/Chord 0.739 0.789 0.836
Radius at CG 350 mm 371.274 mm 391.23 mm
Solidity 1.36 1.28 1.20
Throat/Pitch 0.368 0.369 0.365
Tmax/Chord 0.223 0.223 0.22

4) A steam turbine intermediate pressure module with moderate reaction as claimed in claim 1  wherein the geometry defining parameters of the second stage moving blades at hub  mean and tip sections are according to the following table:
Parameter Hub Section(H-H) Mean Section(M-M) Tip section(T-T)
Chord 35 mm 35 mm 35 mm
Inlet Angle 45 deg 37.66 deg 30.649 deg
Exit Angle -77.10 deg -74.33 deg -70.32 deg
Leading edge radius 2 mm 2 mm 1.5 mm
Stagger Angle -32.49 deg -34.786 deg -36.99 deg
Trailing edge radius 0.4 mm 0.4 mm 0.4 mm
Unguided turning 10.07 deg 10 deg 9.54 deg
Angle of Attack -32.49 deg -34.786 deg -36.99 deg
Area 0.000372 m2 0.000308 m2 0.000212 m2
Axial chord(width) 29.519 mm 28.744 mm 27.95 mm
Camber 122.17 deg 112 deg 100.96 deg
Maximum Thickness 8.0 mm 7.78 mm 7.02 mm
Pitch/Chord 0.74 0.80 0.86
Radius at CG 355 mm 382.17 mm 407.317 mm
Solidity 1.363 1.258 1.17
Throat/Pitch 0.193 0.252 0.352
Tmax/Chord 0.228 0.222 0.200

5) A steam turbine intermediate pressure module with moderate reaction as claimed in claim 1  wherein the geometry defining parameters of the third stage moving blades at hub  mean and tip sections are according to the following table:
Parameter Hub Section(H-H) Mean Section(M-M) Tip section(T-T)
Chord 40 mm 40 mm 40 mm
Inlet Angle 45.314 deg 30.073 deg 17.745 deg
Exit Angle -71.6561 deg -71.49 deg -71.35 deg
Leading edge radius 1.5 mm 1.25 mm 1 mm
Stagger Angle -31.01 deg -36.46 deg -41.69 deg
Trailing edge radius 0.4 mm 0.4 mm 0.4 mm
Unguided turning 9.02 deg 9.04 deg 9.05 deg
Angle of Attack -31.0133 deg -36.4632 deg -41.69 deg
Area 0.0003377 m2 0.0002814 m2 0.00023844 m2
Axial chord(width) 34.28 mm 32.16 mm 29.86 mm
Camber 116.97 deg 101.56 deg 89.0998 deg
Maximum Thickness 9.078 mm 8.659 mm 7.930 mm
Pitch/Chord 0.6353 0.704 0.76
Radius at CG 360 mm 395.83mm 428.45 mm
Solidity 1.58 1.43 1.31
Throat/Pitch 0.2843 0.290 0.296
Tmax/Chord 0.226 0.216 0.198

6) A steam turbine intermediate pressure module with moderate reaction as claimed in claim 1  wherein the geometry defining parameters of the fourth stage moving blades at hub  mean and tip sections are according to the following table:
Parameter Hub Section(H-H) Mean Section(M-M) Tip section(T-T)
Chord 43 mm 39 mm 40 mm
Inlet Angle 35.6337 deg 22.075 deg 8 deg
Exit Angle -71.24 deg -75.64 deg -79.85 deg
Leading edge radius 2 mm 1.5 mm 1 mm
Stagger Angle -29.95 deg -43.058 deg -55 deg
Trailing edge radius 0.4 mm 0.4 mm 0.4 mm
Unguided turning 10 deg 15 deg 20 deg
Angle of Attack -29.95 deg -43.058 deg -55 deg
Area 0.0003372 m2 0.0002273 m2 0.0001592 m2
Axial chord(width) 37.25 mm 28.49 mm 22.94 mm
Camber 106.875 deg 97.722 deg 87.8543 deg
Maximum Thickness 9.88 mm 7.39 mm 6.17 mm
Pitch/Chord 0.6130 0.7739 0.8394
Radius at CG 365 mm 414.36 mm 457.84 mm
Solidity 1.64 1.30 1.20
Throat/Pitch 0.299 0.277 0.257
Tmax/Chord 0.229 0.189 0.154

7) A steam turbine intermediate pressure module with moderate reaction as claimed in claim 1  wherein the geometry defining parameters of the fifth stage moving blades at hub  mean and tip sections are according to the following table:
Parameter Hub Section(H-H) Mean Section(M-M) Tip section(T-T)
Chord 50 mm 46.32 mm 49.2 mm
Inlet Angle 33.0307 deg 7.29 deg -16.78 deg
Exit Angle -73.11 deg -73.08 deg -72.54 deg
Leading edge radius 2 mm 1.75 mm 1.25 mm
Stagger Angle -27 deg -49.64 deg -59.03 deg
Trailing edge radius 0.5 mm 0.5 mm 0.5 mm
Unguided turning 10.9653 deg 11.188 deg 11.369 deg
Angle of Attack -27deg -49.64 deg -59.03 deg
Area 0.000494 m2 0.000207 m2 0.000154 m2
Axial chord(width) 44.55 mm 29.99 mm 25.311 mm
Camber 106.15 deg 80.374 deg 55.75 deg
Maximum Thickness 11.96 mm 7.29 mm 4.81 mm
Pitch/Chord 0.561 0.721 0.774
Radius at CG 375 mm 442.53 mm 499.89 mm
Solidity 1.79 1.409 1.314
Throat/Pitch 0.294 0.311 0.325
Tmax/Chord 0.239 0.157 0.0979

8) A steam turbine intermediate pressure module with moderate reaction as claimed in claim 1  wherein the geometry defining parameters of the first stage nozzle blades at hub  mean and tip sections are according to the following table:
Parameter Hub Section(H-H)
Chord 43 mm
Inlet Angle 0 deg
Exit Angle 80.59 deg
Leading edge radius 3.5 mm
Stagger Angle 55 deg
Trailing edge radius 0.4 mm
Unguided turning 16 deg
Angle of Attack 55 deg
Area 0.0002377 m2
Axial chord(width) 24.66 mm
Camber -80.59 deg
Maximum Thickness 8.1844 mm
Pitch/Chord 0.763
Radius at CG 350 mm
Solidity 1.360
Throat/Pitch 0.2099
Tmax/Chord 0.1903337

9) A steam turbine intermediate pressure module with moderate reaction as claimed in claim 1  wherein the geometry defining parameters of the second stage nozzle blades at hub  mean and tip sections are according to the following table:
Parameter Hub Section(H-H)
Chord 44 mm
Inlet Angle 10 deg
Exit Angle 81.07deg
Leading edge radius 3.5 mm
Stagger Angle 58 deg
Trailing edge radius 0.4 mm
Unguided turning 16 deg
Angle of Attack 58 deg
Area 0.0002255 m2
Axial chord(width) 23.316 mm
Camber -71.07 deg
Maximum Thickness 7.96 mm
Pitch/Chord 0.779
Radius at CG 355 mm
Solidity 1.336
Throat/Pitch 0.20697
Tmax/Chord 0.1810

10) A steam turbine intermediate pressure module with moderate reaction as claimed in claim 1  wherein the geometry defining parameters of the third stage nozzle blades at hub  mean and tip sections are according to the following table:
Parameter Hub Section(H-H)
Chord 61 mm
Inlet Angle 0 deg
Exit Angle 76.70 deg
Leading edge radius 3 mm
Stagger Angle 57 deg
Trailing edge radius 0.5 mm
Unguided turning 8 deg
Angle of Attack 57 deg
Area 0.00042369 m2
Axial chord(width) 33.2228 mm
Camber -76.70 deg
Maximum Thickness 10.9699 mm
Pitch/Chord 0.7270
Radius at CG 360 mm
Solidity 1.411
Throat/Pitch 0.207875
Tmax/Chord 0.179834

11) A steam turbine intermediate pressure module with moderate reaction as claimed in claim 1  wherein the geometry defining parameters of the fourth stage nozzle blades at hub  mean and tip sections are according to the following table:
Parameter Hub Section(H-H) Mean Section(M-M) Tip section(T-T)
Chord 52.45 mm 58.87 mm 64.99 mm
Inlet Angle 0 deg 2.77 deg 5.05 deg
Exit Angle 76.65 deg 78.38 deg 79.97 deg
Leading edge radius 4 mm 4 mm 4 mm
Stagger Angle 50 deg 52.52 deg 54.97 deg
Trailing edge radius 0.5 mm 0.5 mm 0.5 mm
Unguided turning 14 deg 14.04 deg 14.09 deg
Angle of Attack 50 deg 52.52 deg 54.97 deg
Area 0.000427 m2 0.000525 m2 0.000620 m2
Axial chord(width) 33.714 mm 35.821 mm 37.30 mm
Camber -76.65 deg -75.60 deg -74.91 deg
Maximum Thickness 11.04 mm 12.46 mm 13.27 mm
Pitch/Chord 0.809 0.814 0.813
Radius at CG 365 mm 408.24 mm 447.20 mm
Solidity 1.27 1.26 1.26
Throat/Pitch 0.243 0.216 0.192
Tmax/Chord 0.210 0.211 0.204

12) A steam turbine intermediate pressure module with moderate reaction as claimed in claim 1  wherein the geometry defining parameters of the fifth stage nozzle blades at hub  mean and tip sections are according to the following table:
Parameter Hub Section(H-H) Mean Section(M-M) Tip section(T-T)
Chord 58.15 mm 67.36 mm 75 mm
Inlet Angle 5.01 deg 0.51 deg -5.44 deg
Exit Angle 73.71 deg 76.22 deg 78.15 deg
Leading edge radius 4 mm 4 mm 4 mm
Stagger Angle 50.94 deg 52.05 deg 52.99 deg
Trailing edge radius 0.5 mm 0.5 mm 0.5 mm
Unguided turning 9 deg 7.93deg 7.18 deg
Angle of Attack 50.94 deg 52.05 deg 52.99 deg
Area 0.0004515 m2 0.0005856 m2 0.0007229 m2
Axial chord(width) 36.64 mm 41.42 mm 45.13 mm
Camber -68.69 deg -75.70 deg -83.60 deg
Maximum Thickness 11.61 mm 13.06 mm 13.74 mm
Pitch/Chord 0.750 0.755 0.763
Radius at CG 375 mm 427.82 mm 474.05mm
Solidity 1.37 1.35 1.34
Throat/Pitch 0.258 0.221 0.189
Tmax/Chord 0.199 0.193 0.183

13) A steam turbine intermediate pressure module with moderate reaction as claimed in claim 1  wherein said first  second  third  fourth and fifth stage moving blades are provided with a skew angle of 26 deg  20 deg  31 deg  27 deg and 28 deg respectively at root portions.

14) A steam turbine intermediate pressure module with moderate reaction as claimed in claim 1  wherein the length of said first  second  third  fourth and fifth stage moving blades from the base of said root portion to the top of said shroud is 79mm  91mm  119mm  144mm and 179mm respectively.

15) A steam turbine intermediate pressure module with moderate reaction as claimed in claim 1  wherein the length of said first  second  third  fourth and fifth stage nozzles is 40.7mm  49.6mm  65.8mm  87.4mm and 115.918mm respectively.

Dated this 22nd day of May  2012 (for Triveni TurbineLtd)


Dr.Sunil Jajit
GM-IPR