Development of magnetic suspension and balance system for high-subsonic wind tunnel

A magnetic suspension and balance system (MSBS) for suspending a model against a high-subsonic flow has been successfully developed at Japan Aerospace Exploration Agency (JAXA). In the transonic regime, it is difficult for an MSBS to support a model because the aerodynamic forces acting on the model increase with increasing flow speed and its fluctuations also increase accordingly. One of JAXA’s MSBSs for a 10 cm low-speed wind tunnel was modified to improve the control system response. A 500 Hz control system with image sensors was developed, and the proportional-integral controller of the system was replaced with a proportional-integral-differential controller. In addition, to cope with a larger aerodynamic force, more powerful amplifiers were installed. To cope with the directional instability of the model, the drag-counterbalancing magnetic field was modified by increasing the output of the front drag coil. These improvements enabled an ogive-cylinder model with a diameter of 10 mm and a length of 156 mm to be suspended in JAXA’s 10 cm MSBS up to a Mach number of 0.6.