Jet Engine Mass Flow Rate calculation

[vincentryan]

hi
how to find air mass flow rate in jet engine?
we are using thrust/Isp equation to find the mass flow rate for rocket equation. is that any formula available for finding the mass flow rate in jet engine

[CFDFEAGURU]

You could start with a simple thermodynamic heat balance to get a ballpark figure.

Do you have any information on the inlet and outlet conditions or intermediate conditions like the compressor outlet to the turbine inlet?

What is the thrust/Isp equation? Can you post it?

Thanks
Matt

[vincentryan]

For Rocket,
Total Mass Flow rate W = F (Thrust) / Isp (Specific Impulse)
Fuel Mass Flow Rate Wf = W/(r+1)
Oxygen Mass Flow Rate Wo = W-Wf

r = fuel - oxygen mixture ratio

you have asked information about the inlet and outlet conditions or intermediate conditions like the compressor outlet to the turbine inlet.
Take on example of GE 90 - 110B and GE 90 - 110B1 engine.

the fuel flow rate for jet engine is calculated by the following equations
mfuel = Fuel flow rate=mair(f/a)/(B+1)
f/a=Cpg(To5-To4)/HV
help to fine the air mass flow rate

[FredGarvin]

You need to at least know the velocities of the inlet and/or outlet. ISP alone won't be enough. You can do a momentum balance for the control volume.

http://www.grc.nasa.gov/WWW/K-12/airplane/specth.html

http://books.google.com/books?id=t0tDT8BbFPcC&pg=PA114&lpg=PA114&dq=momentum+balance,+jet+engine&source=bl&ots=bhixfR2hHt&sig=ZC10QLm2D4BpzqUd99b9DkvgfBM&hl=en&ei=XrXISoLPHoykMaqTlfMH&sa=X&oi=book_result&ct=result&resnum=1#v=onepage&q=momentum%20balance%2C%20jet%20engine&f=false