[Julian121]

Hi,
I am simulating the Rotor 67 in CFX.
What is the sign of stall inception in numerical simulations?
Can the stall point be regarded as the last converged point or it is the point where both the isentropic efficiency and pressure ratio drop?
I have attached my result from the simulation of Rotor 67.
When the mass flow drops to 32 kg/s, the pressure ratio and isentropic efficiency drop. On the other hand, when I decrease mass flow further to 31.9 kg/s, the pressure ratio slightly increases.
My question is which one of the mass flow rates can be regarded as stall point?

[Julian121]

What I mean is that I need to draw performance map for Rotor 67.
I used total pressure and total temperature boundary conditions at inlet and applied static pressure or mass flow rate at the outlet. When mass flow is lowered it is expected that stall might happen. How can stall be detected from numerical simulation? I read somewhere that when both of pressure ratio and isentropic efficiency drop simultaneously, that mass flow can be considered as the mass flow which stall starts.
I found however this method is not very accurate, because as can be seen from the attached result both of efficiency and pressure ratio can increase again.
I remember from my turbomachinery class that appearance of a region with zero axial velocity does not necessarily mean that stall has induced.
Can last converged solution (steady state simulation) be considered as the near stall mass flow?

Originally Posted by Julian121

Hi,
I am simulating the Rotor 67 in CFX.
What is the sign of stall inception in numerical simulations?
Can the stall point be regarded as the last converged point or it is the point where both the isentropic efficiency and pressure ratio drop?
I have attached my result from the simulation of Rotor 67.
When the mass flow drops to 32 kg/s, the pressure ratio and isentropic efficiency drop. On the other hand,
when I decrease mass flow further to 31.9 kg/s, the pressure ratio slightly increases.
My question is which one of the mass flow rates can be regarded as stall point?

[ghorrocks]

The best practises guide on turbomachinery in the CFX documentation has some very useful tips on running simulation. Have you read them?