Experimental Results Of Scramjet Isolator Under Ununiformity Supersonic Flow

Isolator, one important part of the scramjet, located between the inlet and the combustion chamber to prevent the inlet unstart from the pressure pulsation in combustion chamber.A wind tunnel was built to investigate shock trains under ununiformity supersonic flow in a rectangular isolator. The steady characteristics of the flow in the isolator were discussed both by pressure measurement and the CFD calculation. The oscillations of shock train in a straight duct were experimentally investigated using high speed schlieren photography and wall pressure fluctuation measurements at eight measuring points along the isolator. The direction of the pressure fluctuation propagation and the main frequencies of the shock train oscillations were sought by the statistical analysis, such as the correlation and power spectrum analysis, try to find the reason of the oscillation. The preliminary conclusions as follow:The pressure fluctuation was a low frequency fluctuation which was below 40Hz and propagating downstream. The two main frequencies of the shock oscillation were 6Hz and 14Hz, and shocks composed the shock train oscillated almost simultaneously. The flow vibration in separated region induced by the first shock in shock train may be the reason of the shock train oscillation.