Modified Kantrowitz Starting Criteria for Mixed Compression Supersonic Intakes

Abstract

A proper understanding of the intake starting process of supersonic airbreathing engines is crucial for a successful operation of the supersonic aircraft, especially for three-dimensional geometries in which no reliable starting prediction for a broad Mach number range exists, and the widespread Kantrowitz criterion only provides a conservative prediction. Experimental investigations from the literature are reviewed and put into the perspective of the Kantrowitz theory. First, an empirical relation is developed that is valid for a wide Mach number range, and that can be calibrated to certain classes of intakes by the user. Second, the Kantrowitz assumptions are modified and a semiempirical relation is derived. The semiempirical relation turned out to be an optimistic limit for self-starting.