A wind tunnel test method for Magnus force measurement on rotating spheres using a 1-m magnetic suspension and balance system

Abstract

A wind tunnel test method was developed to investigate the flow around a rotating sphere without support interference. The method was developed using a 1-m magnetic suspension and balance system (MSBS) that can support the model through magnetic force. The sensing and control methods were applied to measure the Magnus force acting on a rotating sphere. In particular, the generation of the negative Magnus force was focused. The aerodynamic forces acting on a rotating sphere without support interference were obtained when the Reynolds number (Re) was approximately 6.5 × 10⁵ based on the diameter of the sphere model, and the spin parameter (SP) ranged from 0.6 to 0.0. In this test, the aerodynamic force evaluation had a large error due to the large fluctuations in the aerodynamic force. However, a Magnus effect was observed. Furthermore, a decrease in the positive Magnus force was observed in the range 0.5 < SP < 0.6.