Starting and Unstarting of Hypersonic Air Inlets: An illustrated guide to flow starting phenomena in the axisymmetric Busemann geometry and other perforated diffusers

The book starts with a brief historical note and an introduction to supersonic and hypersonic flight focusing towards air-breathing technologies. Chapter two further focuses on a technical hurdle that must be overcome in relation to efficient propulsion technologies for possible use in future space access vehicles. Chapters 3 and 4 include new contributions to knowledge, such as the simulation and the effects of boundary-imposed temporal and spatial gradients on the inlet starting phenomenon; these ideas are presented from an illustrative viewpoint. The simulations are based on an inviscid model of a thermally perfect gas. Results indicate, for inlets with high internal contraction, purely accelerative starting is ineffective unless thousands of g's of acceleration are imposed. It is also shown how removal of frangible structures, such as fast rupturing diaphragms, may be used to impose sufficiently high spatial gradients, to permit starting beyond the Kantrowitz-Donaldson limit. For a perforated diffuser, starting takes place if a sonic line, at the leading edge of a slit, occurs at an area ratio equal to, or higher than, the Kantrowitz-Donaldson limit.