Analysis of impact and sensitivity of wall interference parameters in wind tunnel test of rotors

During rotor wind tunnel tests, the downwash flow generated by the model rotor produces significant wall interference as constrained by the wind tunnel walls, and numerous parameters contribute to this interference. To investigate the impact of test parameters on the tunnel wall interference, an analysis method based on the Heyson approach was first established. Verification tests were conducted in both open and closed test sections of the FL-10 wind tunnel at the AVIC Aerodynamics Research Institute, confirming the effectiveness of the method. Subsequently, this method was utilized to analyze how the test parameters influence the tunnel wall interference. Finally, the Sobol algorithm was employed to calculate the sensitivity of wall interference to various test parameters, revealing the degree of sensitivity. The results indicate that, the closer the hub center is to the center of the wind tunnel, the relatively smaller the wall interference is. The effects of wall interference on the rotor performance are opposite in open and closed wind tunnels, with the wall interference in the open tunnel more significant. The advance ratio, thrust coefficient, and rotor model scale are the primary influencing parameters, with the advance ratio playing the most significant role, exhibiting a sensitivity coefficient of 0.894. The total sensitivity coefficients of the thrust coefficient and the rotor model scale are 0.144 and 0.155, respectively, indicating they are secondary influencing parameters.