Development of a wind-tunnel for spinning body using magnetic suspension

Abstract

A wind-tunnel system for spinning body has been proposed to measure hydrodynamic forces acting on the body. In the proposed system, the body is suspended and rotated by electromagnets. The forces are measured from the control signal for suspension. In the previously fabricated apparatus, eight electromagnets were placed around a wind-tunnel. An optical displacement sensor was used to detect the three-dimensional positions of the body. Stable suspension and three-dimensional positioning of the body were achieved. However, it had several problems; the test section area was rather small and vibration was induced by flowing wind to the floator. To solve such problems, a new wind-tunnel using magnetic suspension is developed. It has two and a quarter times test section area. The position sensor is improved to operate in a differential mode in all the directions. Stable suspension and rotation of the floator are achieved. The floator is kept stably without vibration even in the face of wind. The hydrodynamic forces acting on the spinning floator are measured.