AERODYNAMIC FORCES ON A ROTATING SPHERE AT REYNOLDS NUMBER AROUND THE DRAG CRISIS REGION

摘要

Flow characteristics and fluid force on a sphere rotating along with axis perpendicular to mean air flow are investigated using Large Eddy Simulation at three Reynolds numbers of 10~4, 2.0*10~5 and 2.4*10~5. Particular attention has been devoted to a prediction of rotation effect on a promotion of boundary layer transition around the sphere. As a result of simulation, a change of velocity profile around the sphere and displacement of the separation point are visualized. When sphere rotates at Reynolds numbers of 10~4, flow characteristics agree with the flow field explained in the Magnus effect. While sphere rotates at Reynolds numbers of 2.0*10~5, separation point and wake direction are opposite to Reynolds numbers of 10~4 case, and these flow aspects agree with characteristics explained in the negative Magnus effect.