Preliminary Investigation of a Translating Cowl Technique for Improving Take-off Performance of a Sharp-lip Supersonic Diffuser

A preliminary investigation was conducted in quiescent air on a translating cowl technique for improving the take-off performance of a sharp-lip supersonic diffuser. The technique consists of cutting the cowling in a plane normal to its axis and then translating the forepart of the cowling in the forward direction. The leading edge of the fixed portion of the cowling is rounded. Appreciable improved inlet performance was obtained with a cowling translation corresponding to a gap of only 1/4 inlet radius.