[Attesz]

Hi,

I'm simulating a quad rotor helicopter's propeller (only one). During my work, the simulation reaches the convergence very strange, I think. The RMS residuals, domain imbalances are converged, but the monitor points: force on the propellers and the mass flow seems to be not. How can it be, that the imbalances are under 0.0001 but the mass flow "curve" is not constant?

Information:

I'm using ICEM to generate mesh. Cell number: about 800.000. In boundary layer I'm using 5 cells, and the yplus value are under 2, at most under 1. The mesh is fine around the blades and the leading and trailing edges, and of course between the blade tip and wall.

Simulation properties: Steady run, SST turbulence model, 5000 RPM rotational velocity, Frozen Rotor interface type, inlet: total pressure with zero gradient turb, outlet stat pressure with medium intensity, each pressures are 1 bar (0 relative). Timescale: Automatic with Agressive lenght scale option. Initialization: velocity and pressure, with estimated values.

My problem is, that why cannot reach the simulation convergence under 1000 step, and how can I speed up the simulation? It seems to be, that that the massflow and forces can't converge, but RMS values are good.



RMS.jpg
massflow.jpg
force.jpg
If you need more information, let me know!

Thanks for any advice!

Regards,
Attesz