Numerical Investigation of Support-Induced Upstream Flow Disturbances in a Subsonic-Transonic Wind Tunnel

In wind tunnel experiments, support devices inevitably disturb the surrounding flow field, thereby degrading the accuracy of measured aerodynamic data. A new subsonic and transonic wind tunnel has recently been constructed, and the support system for dynamic six degree of freedom experiments is currently under conceptual design. A key challenge is to optimize the support configuration while satisfying stringent flow quality requirements. In this study, the influence of different support configurations on the flow field is investigated numerically by analyzing velocity and pressure distributions. The results show that the optimized six degree of freedom support significantly reduces disturbances in both pressure and velocity fields, with the improvement becoming more pronounced as the Mach number increases. The main optimization measures include the addition of a tail fairing, reduction of the thickness of the connecting bases between the support rods and the sting, and downsizing of the anchor feet. In contrast, the effect of the tail support poles is found to be negligible. It is shown that, overall, the extent of upstream flow disturbance is governed primarily by the separation region and associated momentum loss induced by the support sting, the connecting bases and the anchor feet. Flow separation originates from spiral points or separation lines on the model surface, resulting from viscous effects combined with shock waves generated by the support system.