Design and Fabrication of an Enlarged Wind Tunnel System for Spinning Body Using Magnetic Suspension

Abstract

A wind tunnel system for a spinning body was developed for the measurement of the hydrodynamic forces acting on the body. In that system a ferromagnetic sphere (body) was suspended and rotated by electromagnets. The forces acting on the body were measured from the control signal for suspension. However this existing arrangement is not still appropriate to observe accurate hydrodynamic phenomena around the floating object because the size of the wind tunnel is only 60×60mm. It is required to enlarge the size to reduce the interferences with the walls. In this work, a wind-tunnel system of 100×100mm is proposed to be fabricated. Before the development of the system, the electromagnetic analysis for the system has been carried out. A 3D model of the arrangement is taken in consideration for the analysis. The magnetic flux distributions as well as magnetic force acting on the suspended object are obtained. The magnetic flux densities are analyzed for the variation of current in electromagnets. Actual force acting on the body is also measured. It is observed that the experimental results support the results obtained by numerical analysis. Stable suspension and three-dimensional positioning of the body is achieved in the developed system. Spinning of the body is realized by superimposing two-phase AC signals on the control signal.

The Proposal of Magnetic Suspension using Laterally Control Flux-Path Mechanism

“…In the flux-concentrated type magnetic suspension system [16], a similar flux-path control mechanism was used to achieve stable suspension. The bandwidth of the mechanism was 20 Hz approximately.…”