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Performance calculation of gas turbines

  1. Dec 12, 2008 #1
    Hi fellows;
    we used the gas turbine from solar inc. A catterpillar company model centaur 4502 and 4702.i am resposible for the test cell where the gas turbines engine tests after over hauling.i face some problems.our engines are two shaft the power turbine direct couple with the dynmometer.the rpm of power turbine is 15500 at 100%.we used a load cell to measure the torque and then calculate the horse power by using hp=rpm*armlength*torque/5252.
    Theproblem is that when i correcte these parameters according to the site condition that is corrected horse power which gives the wrong answer i use
    corrected hp=ho*sqrt theta/delta and delta=beromatic pressur standard/measured beromatic pressure and theta is t1/t standard.
    Can any one help me?
  2. jcsd
  3. Dec 12, 2008 #2


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    Show your working out, then spotting the problem will be easier.
  4. Dec 12, 2008 #3
    Working as under
    the conditions are
    standard temp=80 deg f
    standard pressure=14.696 psia
    ambient temp t1=82.7 dgree f
    p_barometic=14.5 psia
    torque=762 ilf
    arm length=1.750 ft
    power turbine rpm=14298
    so now i caculate corrected hp as under
    first theta=82.7+459.67/80+459.67
    so corrected hp=3630.30/1.01351*sqrt of theta
    it is hp=3590 which is wrong data processor show 3854 hp
    how can i calculate the gas turbine is two shaft power turbine direct couple to the dynmometer and the gas turbine from the solor companymodel centaur 4702
  5. Dec 12, 2008 #4


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    You correct to 80°F? Cooky.

    Your calculation for the corrected power is used for turbofans. I am not sure if it is the same for a turboshaft. I will have to check on that since I don't deal with turboshafts on a daily basis.

    You might also want to check your calculation for delta. I get .987
  6. Dec 13, 2008 #5
    yes we correcet our parameters at 80 degree F.
    yes u right the delta is 0.987 sorry for mistake.but how can i found the corrected horse power for two shaft engine in which the power turbine direct connected to the dynomometer?
  7. Dec 14, 2008 #6
    Since you are dealing with a Cat engine your best bet would be to contact the engineering department at Caterpillar.
  8. Jan 22, 2012 #7
    anyone can let me know, how to calculate the mechanical torque of a gas turbine ?
    please. . .
    m waiting.......................
  9. Jan 22, 2012 #8
    how to calculate mechanical torque of a gas turbine ??????
  10. Jan 25, 2012 #9


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    There are lots of ways. What factors do you know?

    Brake power = torque * angular velocity

    Electrical power = brake power * alternator efficiency

    Keep your units consistent. Ask more details in your question and you'll get some more detailed responses.
  11. Jan 26, 2012 #10
    Gas turbine mechanical torque is calculated using the
    equation (1) [3].
    F1 = A1 (1-Wf) +B1 (1-N) (1)
    Equation (2) calculates the exhaust temperature.
    F2 = Tr –A2 (1-Wf) + B2 (1-N) (2)
    Wf – p.u. fuel flow;
    Tr – turbine rated exhaust temperature
    N – p.u. turbine rotor speed;
    A1, A2, B1, and B2 – coefficients used for calculation of
    torque and temperature.
    F1, F2 – functions that calculate torque and exhaust
    temperature respectively.
    nw say???
    how to calculate ?????
  12. Jan 26, 2012 #11
    Just correcting the way that you are, you are not actually doing anything very useful.
    What you need to do is plot 5 points at 100% 95% 90% 85% and 80% load, at each point log N1 N2 EGT CDP, Intake temperature and pressure exhaust gas pressure, intake DP and fuel flow.
    Correct all parameters from test to iso and iso to site, then plot N1 site against Psite and add the site N1 OPLIM where the two lines cross is your maximum power, do the same for N2 EGT CDP.
    If you don't have one get a copy of PTC 22
  13. Jan 26, 2012 #12
    These are industrial gas turbines with a mechanical drive output imagine an an aero jet with a shaft bolted onto the nose bullet, that is your drive shaft.
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