FIELD OF INVENTION
This invention relates to a novel backward curved plate bladed radial
fan, for High Pressure Application, with suitable control mechanism to
regulate the flow and fan performance to meet system demand and to meet
part load operating conditions.
BACKGROUND OF INVENTION
Fans are very essential auxiliaries to boiler for steam generation in the
field of power 8b process industries. These are used as forced draft fan for
providing air for combustion; as a primary air fan for carrying pulverized
coal to combustion chamber and also as induced draft fan for exhausting
the flue gases to chimney as per the system requirement.
The application requirements could be catered by radial and axial flow
fan but such fans need certain control mechanism to control the flow
thereby improving the performance of the fans.
The conventional radial fan (Fig. 1) consists of impeller [1] which is
taper shroud plate bladed design. This impeller [1] consists of back/centre
plate, formed blade [2], taper shroud, ring and hub. The impeller is placed
inside the spiral casing [3] which will act as the diffuser to recover the
kinetic energy of the fluid leaving the impeller, a suction chamber [41 which
uniformly guides the flow inside the fan through a seal [5] to the impeller.
The impeller is driven by conventional motor. The electrical energy input is
converted into aerodynamic output by the rotating impeller.
The present development relates to a backward curved plate bladed
radial fan for high pressure application for use in utilities and process
industries in general and primary air handling application in particular for
better part load performance.
This improved radial fan caters to following criteria:
Flow coefficient f =0.060
Pressure Coefficient V =1.155
Efficiency ? =85.6%
which is void presently.
It is pertinent to mention here that the conventional design will
not meet the aerodynamic parameters like Flow coefficient (p=0.060,
Pressure Coefficient ? = 1.155 which is need for high pressure
application.
The conventional design is with taper shroud impeller which is
difficult in manufacturing where as the invented design is straight
shroud impeller which is easy in manufacturing.
Turbo machinery field is very wide but no national or
international patent could be located for a fan with such aerodynamic
parameters..
The prime considerations for protecting this invention is Plain
shroud Impeller , Plate Blade with Specific camber , angle of incidence
, Suction chamber, Spiral casing 8b Damper which are new and novel
to meet the above aerodynamic parameters requirement.

OBJECTS OF THE INVENTION
The main object of the present invention is to develop a plain shroud
plate bladed radial fan for high pressure application.
Another objective of the invention is to use such fan in utilities and
process industries in general and Primary air handling Application in
particular.
Still another object of the invention to improve the fan performance and to
reduce the power consumption at the part load operation.
Further object of the invention is that the improved fan should have
better pressure, volume performance, reduced vibration and noise, less
power consumption and improved erosion, fatigue life compared with
conventional design.
The foregoing has outlined some of the pertinent objectives of the
invention. These objectives should not be construed to be merely illustrative
of some of the more prominent features and applications of the intended
invention. Many other beneficial results can be obtained by applying the
disclosed invention in a different manner or modifying the invention within
the scope of disclosure.
Accordingly, other objectives and a full understanding of the invention
and the detailed description of the preferred embodiment in addition to the
scope of invention are to be defined by the claims undertaken.
These and other objects and advantages of the invention will be
apparent from the ensuing description.
STATEMENT OF INVENTION
According to this invention there is provided A Novel Backward
Curved Plate Bladed Radial Fan for High Pressure Application, having flow
coefficient f = 0.060 and Pressure Coefficient ? = 1.155, comprising of a plain
shroud Impeller [1] with a plurality of blades, of two types one having plate
bladed blunt body and other with a aerofoil bladed profile body, with
back/centre plate, fitted with narrow width plate blade [2] with
predetermined camber, angle of incidence (9.34°), leading and trailing edge
shapes, a spiral casing [3], and a suction chamber [4] which is specified by
geometry and configuration for guiding the flow through seal [5] to said
impeller and a four flap damper [6] for controlling and regulating the flow.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS;
Further objects and advantages of this invention will be more pparent
from the ensuing description when read in conjunction with the
accompanying drawings wherein:
Figure 1.: Graphical presentation of Conventional Radial Flow Fan
Figure 2.: A Novel Backward Curved Plate Bladed Radial Fan
for High Pressure Application
Figure 3.: Suction Chamber and Damper of the backward curved plate
bladed radial fan.
While the invention is described in conjunction with the illustrated
embodiment, it is understood that it is not intended to limit the invention to
such embodiment. On the contrary, it is intended to cover all alternatives,
modifications and equivalents as may be included within the spirit and
scope of the invention disclosure as defined by the claims.

DETAILED DESCRIPTION OF THE INVENTION
At the outset of the description, which follows, it is to be understood
that the ensuing description only illustrates a particular form of this
invention. However, such a particular form is only an exemplary
embodiment, and without intending to imply any limitation on the scope of
this invention. Accordingly, the description is to be understood as an
exemplary embodiment and teaching of the invention and not intended to be
taken restrictively.
For the purpose of promoting an understanding of the principles of
the invention, reference is now to be made to the embodiment illustres in
the drawings and specific language is used to describe the same. It is
nevertheless to be understood that no limitations of the scope of invention is
hereby intended, such alterations and further modifications in the
illustrated bag and such further applications of the principals of the
invention as illustrated therein being contemplated as would normally occur
to one skilled in the art to which the invention relates.
The current invention illustrates a developed fan, the blade of the
impeller is plain shroud, backward curved plate blades which is of special
profile with smooth entry and exit angles for flow separation and pressure
development for high pressure application. Dimensions of casing & suction
chamber have been optimized to extract maximum kinetic energy. A Four
flap damper with wide spread of aerodynamic parameters has been
developed to have wide spread of operation and easy manufacturing.
A 1000 mm model has been designed, manufactured and performance
tested. Results shown that there is considerable improvement on

aerodynamic performance (about 4 % comparing with conventional design
and further the void zone is filled).
The developed high pressure backward curved plate bladed Fan (Fig. 2
& 3 ) comprises of Impeller [1] having blades of backward curved plate
design. This Impeller consists of back/centre plate, fitted with plate
blade [2]. The parameters like camber, angle of inlet and exit incidence,
leading and trailing edge shapes were specially designed.
The new impeller is placed inside spiral casing [3], which will act as
the diffuser to recover the kinetic energy of the fluid leaving from impeller,
whose diffusivity angle i.e. angle between exit of casing to end of scroll wall
which is 6° and geometry shape were finalized after detailed iterative design
analysis. The number of blades and blade actuations were furnished based
on controllability aspects. The mechanical design of the developed fan was
evolved using Finite Element Analysis.
The specially invented design was converted into 1000 mm model fan
with single suction and performance test was carried out to establish its
aerodynamic performance. A considerable improvement in efficiency
comparing with plate bladed design and considerable reduction in weight
compared with conventional design has been achieved.
All documents cited in the description are incorporated herein by
reference. The present invention is not intended to be limited in scope by the
specific embodiments and examples which are intended as illustration of a
number of aspects of the scope of this invention. Those skilled in art will
know or to be able to ascertain using no more than routine
experimentations many equivalents to the specific embodiments of the
invention described herein.

It is to be further noted that present invention is susceptible to
modifications, adaptations and changes by those skilled in the art. Such
variant embodiments employing the concepts and features of this invention
are intended to be within the scope of the present invention which is further
set forth under the following claims:
WE CLAIM;
1. A Novel Backward Curved Plate Bladed Radial Fan for High
Pressure Application, having flow coefficient f = 0.060 and
Pressure Coefficient ? = 1.155, comprising of a plain shroud
Impeller [1] with a plurality of blades, of two types one having
plate bladed blunt body and other with a aerofoil bladed profile
body, with back/ centre plate, fitted with narrow width
plate blade [2] with predetermined camber, angle of incidence
(9.34°), leading and trailing edge shapes, a spiral casing [3], a
suction chamber [4] which is specified by geometry and
configuration for guiding the flow through seal [5] to said
impeller and a four flap damper [6] for controlling and
regulating the flow.
2. A Novel Backward Curved Plate Bladed Radial Fan, as claimed in
Claim 1, wherein said impeller [1] is housed inside the spiral
casing [3] which acts as a diffuser to recover the kinetic energy
of the fluid leaving from impeller
3. A Novel Backward Curved Plate Bladed Radial Fan, as claimed
in Claim 1, wherein said impeller [1] is optimized such that
it occupies less space (9%) and less weight (15%) compared
to the conventional design.
4. A Novel Backward Curved Plate Bladed Radial Fan, as claimed
In Claim 1 and Claim 2, wherein the parameters of said angle of
incidence, leading 8s trailing edges as specially shaped for
handling high pressure.
5. A Novel Backward Curved Plate Bladed Radial Fan, as claimed
in Claim 1 and Claim 2, where the said suction chamber is'
attached with a four flap damper [5] for better controllability.
6. A Novel Backward Curved Plate Bladed Radial Fan, as claimed
in Claim 1, substantially as herein described.

A Novel Backward Curved Plate Bladed Radial Fan for High Pressure
Application, having flow coefficient φ = 0.060 and Pressure Coefficient ψ =
1.155, comprising of a plain shroud Impeller [1] with a plurality of blades, of
two types one having plate bladed blunt body and other with a aerofoil
bladed profile body, with back/centre plate, fitted with narrow width
plate blade [2] with predetermined camber, angle of incidence (9.34°),
leading and trailing edge shapes, a spiral casing [3], and a suction chamber
[4] which is specified by geometry and configuration for guiding the flow
through seal [5] to said impeller and a four flap damper [6] for controlling
and regulating the flow.