design of a specified compressor

1. Design of Transonic
Axial Compressor
{
Sai Kiran Goud.M

2.  Transonic axial flow compressors are today widely used in aircraft
engines to obtain maximum pressure ratios per single-stage.
 . High stage pressure ratios are important because they make it
possible to reduce the engine weight and size and, therefore,
investment and operational costs.
 Performance of transonic compressors has today reached a high
level but engine manufacturers are oriented towards increasing it
further.
 Another important target is the improvement of rotor stability
towards near stall conditions, resulting in a wider working range.
 Today’s high efficiency transonic axial flow compressors give a total
pressure ratio in the order of 1.7-1.8.
Introduction

3.  Based on multistage axial flow compressor of the M7A-O2 gas
turbine establishes a higher pressure ratio and a large amount of
air flow than the M7A-O1.
 By adopting transonic stages with the characteristics of high
pressure ratio, the air flow rate and pressure ratio are increased.
 A preliminary design for a nine-stage axial flow compressor was
produced from an initial specification. This design is presented
here, and is criticized. Alterations are then made to the design to
compensate for its deficiencies.
Problem Definition

4.  By considering the initial required conditions for
the design of axial compressor the following
parameters are designed.
 All the blade angles at mean for both rotor and
stator of the compressor
 Total pressure ratio of each stage and the
complete compressor.
 Total shaft power.
 Assuming every stage has the same mean radius
with rotor blade angle changing by ‘12 degree’

5. Design Specifications
Number of stages n 9
Initial design specification
Rotating Speed N 9000rpm
Ambient pressure P01 15.7Psia
Ambient temperature T01 519R
Mean axial velocity Va 520ft/s
Radius of the rotor at tip rt 12inches
Radius of the rotor at hub rh 8inches
Change in rotor blade angle per
stage
β1 – β2 12degree

6.  Calculate the mean radius rm= rt+ rh/2 = 10.
Therefore, hub/tip ratio = 0.83ft.
 Calculate the blade velocity ‘Um’ at the mean, by
using the formula
Um= 2π.N.rm / 60 = 781.86ft/s
 Calculate the inlet blade angle β1 ,
Tan β1 = U / V1 = 56.30
degrees
 As given, Change in rotor blade angle per stage, β1 –
β2= 10, calculate β2 = 46.30
degrees.
 From the velocity triangle , find the value of Wu2,
 Tan β2 = Va / Wu2 = 496.9 ft/s
Procedure / Calculations

7. Velocity Triangle

8.  In velocity triangle we can get the value
of Vu2 by subtracting it from ‘U’
= 284.96ft/s
 Using velocity triangle and the value of
Wu2 , calculate ‘α2’ , i.e.
Tan α2 = Vu2 / Va =
28.36degree
 Now find stagnation enthalpy difference
by using the formula,
Ϫ hos= U. Vu1 = U (U- Va tan β2) =
7.42btu/lbm

9.  By using Cp (To2-To1) = Ϫ hos, find temperature per stage
T o2 = 539R
 Pressure ratio per stage , as T o2 = T03, calculate P03/ P01,
P03/ P01 = ( T03 /T01)k/k-1 =1.145
 Calculate the outlet temperature of the compressor, Toe
Cp (Toe-To1) = Ϫ hos = 703.5R
 Calculate the overall pressure ratio of the compressor,
Toe / To1 = (Poe / Po1)k-1/k = 2.89
 Using the above equation find out ‘Poe’. = 45.5psia
 For finding the pressure rise per stage, calculate T1,
T1= T01- V1
2/ 2 Cp =496.51R

10.  Now calculate P1,
P1/P01 = (T1/ T01)k/k-1 = 13.44psia
 Now calculate 흆1, by using the equation,
흆1= P1 / RT1 = = 0.0507
lbm/ft3
 Calculate area of the rotor ,
2- rh
A1= π (rt
2)
=251.2ft2
 Calculate the mass flow rate,
M .= 휌1. V1. A1 = 66.57
lb/s
 Finally calculate the shaft power,
Ps= m..n. Ϫ hos = 4445.54hp

11. Inlet blade angle at mean β1 56.30degree
Outlet Blade angle at mean β2 46 degree
Blade angle at mean α2 28.36degree
Pressure ratio per stage P03 / P01 1.145
overall pressure ratio Poe / Po1 2.89
mass flow rate m' 66.57lb/s
shaft power Ps 4445.54hp
Results
Results

12.  Hence, for a transonic axial compressor,
determined the following values,
1. Blade angles at mean for both stator and
rotor.
2. Total pressure ratio of each stage and the
complete compressor.
3. Total shaft power.
Conclusion

13. Thank
You