For the purpose of examing supersonic intake instability, the authors have designed and constructed a supersonic wind tunnel of the blow down type, in which the test section dimension is 200mm x 180mm and its Mach number capability is 2.0. Using this supersonic wind tunnel, experiments on inlet buzz are made. The air intake model is an all external compression type with a conical center body and an outer cowling. Test parameters used are the exit port area or the throttle ratio (T. R.) and the center body position relative to the cowl lip or spacer combination (No. A～C). The effect of attack angle (α) is also examined. The following results are obtained for experiments. In the subcritical regime unstationary phenomena occur and some characteristic frequencies are observed on the pressure records, which are measured with strain gauge type pressure transducers located at several spots on the center body and the cowling wall. The occurrence of inlet buzz and the transition from lower frequency to higher one are studied by decreasing T. R. and continuously recording the pressure fluctuations. In addition, these pressure records coincide fairly well with the motions of the bow shock wave, which are photographed with a Schlieren high speed camera. Based on the experimental results from the model with and without the center body, it can be stated that the center body has a significant effect on the buzz characteristics of supersonic air intake, especially when buzz occurs at a high frequency.
超音速空気取入口のバズに関する実験的研究
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