[sfallah]

Dear all;
I read a paper and a thesis which used time dependent static pressure at outlet ,which controlled by outlet mass flow rate, for simulating NASA 67 rotor in stall condition.
Paper:"Stall inception in a transonic axial fan" by H Khaleghi et al.
Thesis:"NUMERICAL SIMULATION OF ROTATING STALL AND SURGE ALLEVIATION IN AXIAL COMPRESSORS" by Saeid Niazi at "Georgia Institute of Technology"
This formula is: P(n+1)=p(n)+k(mdot(p)-mdot(t)), n is time index.
Where a value of 0.20 for K is used in their study. The quantity mdot(p) is an outlet mass floe rate and mdot(t) is an input parameter that represents the nominal mass flow rate and lets the compressor run at different operating conditions.
How can i use this formula in CFX to capturing stall condition for Nasa 67 rotor???? Please help me.
Regards

[ghorrocks]

The equation does not make physical sense to me as it appears to say the pressure at the next time step is a function of the previous time step, but there is no time step size factor in there. This means the function will not converge with time step refinement.

[sfallah]

K involve time step, original equation is:
dp/dt=(ap^2/Vp)*(mdot(p)-mdot(t)) ap is local sound velocity and Vp is plenum volume. this eqution is expressed in mentioned references completely.

[ghorrocks]

How can i use this formula in CFX to capturing stall condition for Nasa 67 rotor????

If you are asking what does this formula do to help capture a stall condition - I have no idea. You will have to research that as you have the reference to it.

If you are asking how do you implement this condition in CFX - please attach an example of what you have tried so far and the errors it gives.