FIELD OF INVENTION
The present invention relates to an improved air baffles for hydrogenerators.
More, particularly, the invention relates to air baffles to guide the air flow for
axial fans used to cool the hydrogenerator.
BACKGROUND OF THE INVENTION
In hydrogenerator, two types of fans are used to cool the generator. One type
of fan is centrifugal fan for which no baffle is required to guide the flow but air
guides are required. The other type of fan is axial which requires air baffles
along with air guides to guide the flow to meet the required flow and pressure.
The axial fans provided on top and bottom of rotor, are mounted throughout
circumference and baffles are fixed at inner diameter side of fans on stationary
parts named as upper and lower bracket. The details are shown in Figure 1.
In prior art, the baffles were also provided to guide the flow. These baffles were
manufactured in many segments by thin sheet of steel. The segments were joint
together to form a circle at inner diameter side of axial fan. The work of joining

was carried out at project site. The details of this arrangement are shown in
Figure 1. In the existing design, the axial fans do not give the required flow and
pressure due to non formation of smooth circle with the segmental baffles
because the segments are being distorted due to welds and thin sheet steel.
Further, the diameters of rings are about 4 to 5 meter and hence maintaining its
circularity is very difficult due to the distortion coming by the welding.
The main disadvantages of existing system are as follows:-
1. Lower efficiency of axial fans due to non formation of smooth circle with
the segmental baffles.
2. Higher temperatures of stator core and windings due to less air flow.
3. More assembly time at site due to distortion of baffle segments made of
steel, sheet.
4. Higher weight due to use of steel sheet.

The fans were not giving the adequate performance as per design due to partial
guided flow by the existing arrangement of baffles. The temperatures of stator
core and winding were found more due to inadequate performance of fans.
Hence, higher capacity fans were being provided which resulted higher losses
and in turn lower efficiency which was a great loss for the company as well as
nation. In view of this, the improved air baffles have been explored and
invented to achieve the required performance of fans.
OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose an improved air baffles for
hydrogenerators which eliminates the possibilities of non formation of smooth
circle with the segmental baffles.
Another object of the invention is to propose an improved air baffles for
hydrogenerators which is capable of achieving the designed temperature of
stator core and winding due to adequate air flow.

Further object of the invention is to propose an improved air baffles for
hydrogenerators which eliminates the disadvantage of distortion of baffle
segments so that assembly time at site is reduced.
A still further object of the invention is propose an improved air baffles for
hydrogenerators which is capable of a cost reduction of 30 %.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention can now be described in detail with the help of the figures of the
accompanying drawings in which:
Figure 1 shows arrangement of steel air baffles according to prior art.
Figure 2A shows arrangement of moulded air baffles according to the invention.
Figure 2B shows fixing of air babbles with upper bracket (18)
according to the invention.
Figure 2C shows fixing of air babbles with lower bracket (17)
Figure 3A shows a complete circular air baffle according to invention.
Figure 3B shows a detail of segments according to invention.
Figure 3C shows joining details of segments according to invention.

DETAILED DESCRIPTION OF A PREFERRED
EMBODIMENT OF THE INVENTION
In the invented design, the air baffles (1) have been made by moulding using
fiber reinforced polymer (FRP) for formation of smooth circle at inner diameter of
axial fans (19, 20). Because of the pattern used for moulding, an excellent finish
is achieved and the diameter made is very accurate. The fixing arrangement is
similar to the prior art as shown in Figure 1 of sheet steel baffles. The complete
arrangement of moulded FRP baffles is shown in Figure 2(A), 2(B) and 2(C).
The air baffle assembly (1) consists of upper air baffle (1A) and lower air baffle
(IB) which are circular. The air baffle assembly (1) is made of number of FRP
segments (2) which are joined at site to form the circle as shown in Figure 3(A),
3(B) and 3(C). The segments (2) due are made by moulding on pattern using
fiber reinforced polymer and consists of inserts (3) for fixing with stationary parts
upper (18) and lower brackets (17), inserts (4) for joining segments (2) and
fixing the air splitters (5) as shown in Figure 2(C). The segments (2) are joined
with the help of joint strip (6) made of flexible PVC sheet, screws (7), nuts (8)

and locking plates at inner diameter side (9) and outer diameter side (10) as
shown in Figure 3(C). The top side air baffles (1B) are fixed on to the upper
bracket (18) as shown in Figure 2(A) and 2(B) while bottom side air baffles (1A)
are fixed on to the bottom bracket (17) as shown in Figure 2(A) and 2(C). These
baffles are fixed on to the support plate (11) with the help of screws (12) and
washers (13) as shown in Figure 2(B) and 2(C). The air splitters (5) are fixed on
to baffles with the help of screws (14), nut (15) and locking plate (16), as shown
in Figure 2(A) and 2(C).
The invention baffles have the following advantages:
(1) The new design of air baffle assembly helps forming of smooth and
accurate circle resulting no loss in generator efficiency.
(2) Required designed temperatures of stator core and windings are
maintained due to adequate air flow.
(3) Reduction in assembly time at site as there is no distortion of baffle
segments.
(4) There is a cost reduction of about 30%.

WE CLAIM
1. An improved air baffles for hydrogenerators comprising:
- the air baffle assembly (1) consisting of an upper air baffle (1A)
and lower air baffle (1B);
- the said air baffle assembly made up of segments (2) inserts (3, 4)
and air splitters (5);
characterized in that,
- the air baffle assembly (1) is made of a plurality of moulded
segments 2 which consists of inserts (3) for fixing with upper (18)
and lower brackets (17) and inserts (4) for joining the segments
and fixing the air splitters (5) wherein the segments (2) are joined
by joint strip (6) screws (7), nuts (8) and locking plates at inner
diameter side (9) and outer diameter side (10).
2. An improved air baffle as claimed in claim 1, wherein the segments
are made of fiber reinforced polymer (FRP).
3. An improved air baffle as claimed in claim 1, wherein the joint strip
(6) is made of flexible PVC sheet.

4. An improved air baffle as claimed in claim 1, wherein the top side
air baffles (1B) are fixed on to the upper bracket (18) through
support plate (11), screws (12) and washers (13).
5. An improved air baffle as claimed in claim 1, wherein the bottom
side air baffles (1A) are fixed on to the lower bracket (17) through
support plate (11), screws (12) and washers (13).
6. An improved air baffle as claimed in claim 1, wherein the baffles (1)
are fixed with air splitters (5) by screws (14), nuts (15) and locking
plate (16).

An improved air baffler for hydrogenerator consists of an upper air baffle (1A)
and lower air baffle (1B) which are made of a plurality of moulded segments.
The segment consists of inserts (3) for fixing with upper (18) and lower brackets
(17) and inserts (4) for joining the segments and fixing the air splitters (5). The
segments are joined by joint strip (6), screws (7), nuts (8) and locking plate at
inner diameter side (9) and outer diameter side (10). The segments (2) are
made of fibre reinforced polymer (FRP) for formation of smooth circle at inner
diameter of axial fan. FRP air baffles (1) are fixed on to upper (18) and lower
bracket (17) by support plate (11), screws (12) and washer (13).