Numerical Analysis of the Magnus Effect on the Forces Past an Axisymmetric Body at High Incidence

Abstract

Rolling motion is the motion where a body flies at a constant pitch angle α with respect to the freestream velocity vector, while undergoing a constant angular rotation p about its longitudinal axis. An effect of this motion is the appearance of a Magnus force and moment, which add to the static forces and moments. One problem that arises at high angles of attack is that the flow is not symmetric in these conditions, leading to a non-zero side force at a zero spin rate. Additionally, the roughness induces a roll angle effect on the side and normal forces, and therefore on the moments. Then, at low roll rates, the prediction is difficult to assess due to the complex interactions due to the moving walls, roughness and shedding vortices that appear at the leeside. Computational fluid dynamics (CFD) is an appropriate tool for investigating these non-linear effects, particularly at high angles of attack. It can help provide a more accurate model of the forces and moments and provide insight into the complex flow field. It is necessary to use high-level turbulence models, transient calculations and fine grids in order to capture the flow field and obtain accurate forces, moments and their derivatives. The calculations have shown that the flow is not symmetrical with the roll rate. There are differences depending on the sign of the spin velocity. The Magnus forces are difficult to determine from the total forces, as there are significant non-linear effects.