Investigation Of Flow Characteristics Of Scramjet Isolator Under Asymmetric Supersonic Flow

In order to simulate the actual flowfield at the exit of the hypersonic inlet, the flow in the scramjet isolator was investigated under asymmetric incoming flow.In order to investigate the characteristics of wall pressure fluctuations in a rectangled isolator, wind tunnel experiments were performed on the isolator using wall pressure fluctuation measurements and statistically analysis. Secondly, in order to analyze the characteristics of the flow in the isolator, numerical investigations were presented on the shock/boundary layer interactions in the isolator. Finally, in order to improve the shock-holding capability of the isolator and reduce the length of the isolator, computational fluid dynamics simulations were performed on the isolator with a ramp.The results indicated that the upper wall pressure fluctuations are larger than the lower wall pressure fluctuations, but the frequency is the same. The mean propagation velocities in the upper wall are different from the lower wall's. The upstream propagating fluctuations decreases slightly with an increased distance, but the downstream propagation decrease rapidly with the distance. When the exit is supersonic, the frequency of wall pressure fluctuation is below 70Hz, but when the exit is subsonic, wall pressure fluctuations contain components of both low frequency oscillations, below 70Hz, and components of high frequency oscillations of 100Hz and 200Hz. The separated regions asymmetrically appeared in the cross section of the isolator and secondary-flow features were evident in the shock train regions. When the length of the isolator don't change, the shock-holding capability of the isolator could be improved with the optimum ramp design .The performance of the isolator is better when the ramp is located in the wall of thick boundary layer at the isolator entrance. The overall length could be reduced by 35 percent in the condition of the numerical calculations.