[Zhifeng]

Hi,

I am simulating a transonic fan cascade flow in a stable framework, which means, the inlet Mach number is 1.25 (rotating speed 369m/s and axial speed 189m/s). When I define a subsonic inlet with total pressure and flow direction, the static pressure is lower than the experiment, when I define a supersonic inlet, there will be an extremely high Mach number at the first grid behind the inlet. Does anybody have an idea to solve it?

Besides, I wonder if it is correct to use the parameters from a rotating framework experiment for the stable framework cascade flow, just keep the temperature and pressure unchanged, regard the relative total temperature and relative total pressure as the stable total temperature and stable total pressure.

Thanks

[Zhifeng]

Correction: This error is because I defined the inlet as supersonic. For the supersonic cascade flow, one approach is to define a large radius and a low rotating speed to reduce the influence of centrifugal and Coriolis forces, and simulate with normal subsonic inlet condition. If the effect of centrifugal and Coriolis forces must be eliminated, then another softwares should be used.

[ghorrocks]

CFX can handle non-rotating simulations just fine (ie no centrifugal and coriolis forces). You just do not make the domain rotate, as simple as that. No need to go to other software for this case.

[Zhifeng]

Originally Posted by ghorrocks

CFX can handle non-rotating simulations just fine (ie no centrifugal and coriolis forces). You just do not make the domain rotate, as simple as that. No need to go to other software for this case.

Hi Ghorrocks,

I used to think so too, but the problem is: the velocity perpendicular to the inlet is supersonic. I have tried to simulate in your way with an initial value from the rotating simulation and a timestep with the CFL factor of 1, the result is still wrong. I said to use another software, because they have a function called translation, instead of rotation, and can solve this problem.

By the way, some other software can simulate in the way you said, the results are inaccurate but acceptable.

Regards

Zhifeng

[TurBoris]

Hi,

I did the CFD analysis of transonic S-shaped cascade of ARL-SL 19 in Star CCM+ with the boundary conditions of supersonic inlet and pressure outlet. I defined the Mach number, flow direction, static pressure and temperature for inlet and static pressure for outlet. The results were accurate enough (the result is attached). The domain was 2D and periodic BC's were used. Normally, with these BC configurations you should have a good solution.