[tomasOrt]

Hello to all,

I am trying to simulate a drone rotor in forward flight condition. Subsequently I have done the simulations for fixed point flight condition using the frozen rotor method. Therefore, I already have a reference of the thrust and torque values I should get.

My domain consists of a static rectangular 3D domain and an inner cylinder for the rotating zone. I am using k-w SST, transient, sliding mesh. As boundary conditions I have inlet for ifront and side faces defined by magnitude and direction of flow and pressure outlet on the back face. Methods: coupled and double precision, Controls all with default settings except flow courant number at 2e7 to converge faster.

The inlet flow in the inlets simulates the forward condition, initially I performed an analysis of the mesh as well as the step time effect and the results were as expected. However, I would like to simulate cases where the rotor is slightly inclined. To do this, instead of modifying the geometry, I am analogously applying this angle to the inrush current. Specifying its direction. However, as I do that, the thrust estimate decreases considerably, to values similar to the fixed point condition, when in fact the variation between the case without angle and with angle should be practically the same. Mesh, geometry and set up remain exactly the same, I just change the direction of the inlet flow and the results vary considerably. As step time I use the equivalent of a 1 degree angular step of the rotor.

Does anyone know what is the cause of this phenomenon?