A preliminary investigation of the use of expanders to generate hypersonic flow in a wind tunnel

A preliminary investigation of secondary nozzles was carried out using the UTIA 5 x 7 supersonic wind tunnel. These secondary nozzles, called expanders, are mounted on the main tunnel nozzle and serve to accelerate a supersonic flow to higher Mach numbers with attached boundary layers . In the present tests the speed of the wind tunnel, in which the flow with atmospheric inlet was normally separated for pitot Mach number MH 4.0, was increased to MH = 5. 15, with attached and relatively thin boundary layers . The presence of the expanders reduced the effective working aection area to 3 x 5 but a relatively small modification to the tunnel could yield a working section of useful size (5 x 5).