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

A new wind tunnel system for a spinning body is designed for the measurement of the hydrodynamic forces acting on the body. In this system a ferromagnetic sphere (floator) is considered to be suspended and rotated by electromagnets. The diameter and weight of this floator are 19.5mm and 28.4 g, respectively. For observing the accurate hydrodynamic phenomena around the floator by reducing the interferences with the walls, the cross section of the test chamber of the wind tunnel in the vertical plane is set to be 100×100 mm. Wind flow is considered to be in the negative x-axis direction. For compensating the effect of the wind flow, force in the opposite direction is necessary. To make a significant difference of the resultant horizontal force in this direction, the poles are arranged asymmetrically, which is a special characteristic of this design. 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.