Mechanism Of The Interaction Between Flowfield And Wall Temperature In Rectangular Isolators

The mechanism of the interaction between flow field and wall temperature was investigated in rectangular scramjet isolators used a combination of numerical simulations and experiments.Based on the new research about wall temperature influence on a shock train by Olivier, The flow characteristics of the high aspect ratio rectangular cross-section isolator with different wall temperatures were investigated by 3D numerical simulation. In addition, comparisons of the characteristics were carried out under different incoming flow and aspect ratio. The studies demonstrated that the factor A influencing shock train length is involved in the boundary-layer momentum thickness and Stanton number. When the back-pressure is low, the increase of the shock train length with increasing wall temperature is suggested because of the boundary-layer momentum thickness mainly affecting the factor A, while the opposite effect to the results in the high back-pressure ratio. The high total temperature has a bad influence on the shock train and shock-holding capability. The boundary-layer momentum thickness and Stanton number are larger in a low aspect ratio rectangular isolator, the decrease of the aspect ratio restrain the capability of shock holding and the degree of wall temperature influencing shock train length.The aerodynamic performance of a low aspect ratio isolator with symmetric supersonic flow was experimentally investigated by using a controlled wall temperature manner and statistically analysis. It was found that wall temperature has an important impact on the shock train leading edge. The change rule is similar to the results of 3D numerical simulation. Total pressure recovery coefficient is increased with the wall temperature rising, while the critical backpressure is decreased. The average factor A and the wall temperature have a proportional relation. Wall temperature doesn’t affect the morphological structure of shock train. Related experimental results show consistent trends with the numerical simulation.The unsteady characteristics and the leading edge detection techniques of shock train were studied in an isolator with different wall temperatures. The results validated that the consequence of the separation bubbles interaction leads to the shock train oscillation from the combined impact of the back-pressure ratio and wall temperature. The measurements used in forecasting the shock train leading edge include the ratio of static pressures, static pressure increase, and static standard deviation. In the analysis, the first two approaches can accurately detect shock train leading edge locations.