Mohmmad Bahreini Can you ask your question more accurately ?What are exactly means ? Do you want check mass flow rate in the results of simulation or you mean defining mass flow rate for boundary conditions? Also it will be great if you tell which program you use to do simulation.

Vladimir Dorofeev Thank you For your Answer, I have a 0D Dynamic Code for Simulation Gas Turbine(FORTRAN code),For calculate mass flow rate in compressor I should low-off mass flow rate that get out of BV1( bleed valve low pressure) and BV2(Bleed valve high pressure). I looking for a equation or something like that for calculate mass rate of bleed valve. Do you have any paper or Report that has a equation or lookup table that calculate mass rate bleed valve in gas turbine?

Mohmmad Bahreini I think you can use the tables of gasdynamic functions (fig.1) (russian: таблицы газодинамических функций). If you know pressure ratio before and after your valve you can find gasodynamic functions of mass flow rate q(L) by using tables of gasodynamic functions. After that you can calculate absoltely mass flow rate using this formula (fig.2). This formula taken from book " The theory of turbomashines " the autor: doctor of technical science Kirilov I.I. (russian: Кириллов И.И.Теория турбомашин. Л., "Машиностроение". 1972 г.) : G = f*sqrt(k/R*(2/(k+1))^((k+1)/(k-1))) * P*/sqrt(T*) *q(L)

,where

f - sectional area

k=1,4 (for air)

R=287 [J/(kg*K)] (for air)

P* - total pressure before valve

T*-total temperature before valve

q(L) - gasdynamic function of mass flow rate