8/19/2019 Axial and Radial Flow Turbines Solved Problems Ragaza

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Margarito Ragaza II

Axial Flow Turbines

1. Consider an impulse gas turbine in which gas enters at pressure = .! bar and lea"es at

1.#$ bar. The turbine inlet temperature is 1###% and isentropic e&&icienc' o& the turbine is#.((. I& mass &low rate o& air is !( )g*s+ nozzle angle at outlet is , o+ and absolute "elocit'

o& gas at inlet is 1-# m*s+ determine the gas "elocit' at nozzle outlet+ whirl component at

rotor inlet and turbine wor) output. Ta)e+ γ =1.$$+ and Cpg =1.1-, )*)g% 

T ' 02

T 01

=( p 02

 p01

)( y−1)

 y

T ' 02=T 

01( p02

 p01

)( y−1 ) y =1000(

1.03

5.2)0.248

=669 K 

T 02=T 01−ŋt  (T 01−T ' 02)=1000−0.88 (100−669 )=708.72 K 

1

2 (C 2

2−C 1

2 )=C  p(T 01−T 02)

C 2=√ [(2 ) (1147 ) (1000−708.72 )+19600 ]  = (!/.$$ m*s

C w2=829.33sin57 °

=0/. m*s

W t =mC  pg (T 01−T 02)=(28 ) (1.147 ) (1000−708.72 )=9354.8 KW 

!. In a singlestage gas turbine+ gas enters and lea"es in axial direction. The nozzle e&&lux

angle is 0(2+ the stagnation temperature and stagnation pressure at stage inlet are (##2C

and - bar+ respecti"el'. The exhaust static pressure is 1 bar+ totaltostatic e&&icienc' is

#.(+ and mean blade speed is -(# m*s+ determine the wor) done and the axial "elocit'

which is constant through the stage Assume γ =1.$$+ and Cpg = 1.1-, )*)g%.

8/19/2019 Axial and Radial Flow Turbines Solved Problems Ragaza

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$. In a singlestage gas turbine+ gas enters and lea"es in axial direction. The nozzle e&&lux

angle is 0(2+ the stagnation temperature and stagnation pressure at stage inlet are (##2C

and - bar+ respecti"el'. The exhaust static pressure is 1 bar+ totaltostatic e&&icienc' is

#.(+ and mean blade speed is -(# m*s+ determine the total to total e&&icienc' and the

degree o& reaction.

-. A singlestage axial &low gas turbine with e3ual stage inlet and outlet "elocities has the

&ollowing design data based on the mean diameter4

8/19/2019 Axial and Radial Flow Turbines Solved Problems Ragaza

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Calculate the rotorblade gas angles+ the degree o& reaction+ blade loading coe&&icient+ and

 power output.

. From the pre"ious problem+ determine the total nozzle throat area i& the throat is situated

at the nozzle outlet and the nozzle loss coe&&icient is #.#.

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