Investigation on the flow rotation effect and elimination in hypersonic wind tunnel

Wind tunnel experiments require high quality flow field,but in some hypersonic wind tunnel,the inlet flow may be rotated for preventing the local overheating of the heater.In order to eliminate the rotation,a reverse rotating flow is added into the main stream before the stability section of the wind tunnel.A wing model and a high precision roll balance were designed to study the total effect of the flow rotation in the hypersonic wind tunnel.The rolling moment measurements are carried out in the Φ0.3m hypersonic low density wind tunnel of CARDC under the test conditions of Mach 6, stagnation pressure of about 2×10⁵Pa and room temperature nitrogen.The results show the rotation exits and the maximum rolling moment coefficient is 1.657×10^-3;Reverse flow of about 2% total flow flux can reduce the rolling moment coefficient by 2 orders of magnitude. It is proved to be an effective solution for improving the quality of the wind tunnel flow field.