Experimental Measurements of Starting Loads and Model Behaviors in the Indraft Supersonic Wind Tunnel

Abstract

Measurements of starting load in the indraft supersonic wind tunnel of Muroran Institute of Technology were conducted for Mach 2, 3 and 4 conditions with the AGARD-B model. The high-speed photographs covering the behaviors of the wind tunnel model from the start to end of the operation were taken. Those photographs make clear that the oscillations of the model coincide with the measured starting load oscillation and starting loads were caused by two shock waves. The first shock wave is the reflection shock, generated at the nozzle throat by expansion wave reflection. The second wave is comprised asymmetric oblique shock waves (AOS) coming from upstream. AOS can generate asymmetric conical shock (ACS) around the nose cone of the model, which would have directly caused the starting loads on the wind tunnel model. Based on these observations, propose a conical shock theory, as an alternative starting load prediction theory instead of the normal shock theory.