Experimental study on influence of incoming total temperature on hypersonic boundary layer transition

Wall-temperature-ratio/temperature is a parameter that needs attention in the study of hypersonic boundary layer transition. The boundary layer transition experiment was carried out in CARDC Φ2 m shock tunnel, the model is a 7° half-angle cone model with the nosetip bluntness of 0.05mm, the Mach number is 9.86 and 9.97, the unit Reynolds number is 8.9 × 10⁶/m and 8.4 × 10⁶/m, and the total temperature is 1332.2 K and 956.6 K, respectively. Under the conditions of approximately the same Mach number, Reynolds number, noise level and wall temperature, the effect of the total temperature of the wind tunnel on the transition of the hypersonic boundary layer is studied. The heat flux sensor is used to measure the transition position and the high frequency fluctuation pressure sensor is used to measure the fluctuation characteristics of the boundary layer. The experimental results are compared with the transition prediction results of the γ−Re_θ−MT model and the linear stability theory results, respectively. The heat flux distribution results of the cone calculated by the transition model are in good agreement with the wind tunnel test results, and the transition positions obtained experimentally and theoretically are basically the same, indicating that the numerical calculation method of the transition model has high reliability. The pressure fluctuation results measured by the PCB sensor and the theoretical analysis results of the linear stability are mutually confirmed, showing the second mode wave spectrum characteristics of the two cases of high and low total temperature under wind tunnel conditions.