Some Key Issues in Hypersonic Propulsion

Abstract

This paper summarizes and discusses some critical aspects of flying hypersonically. The first is the L/D (lift over drag) ratio determining thrust and that in turn depends on the slenderness Küchemann’s τ parameter. This second parameter is found to depend on the relative importance of wave versus friction drag. Ultimately, all engineering drag is argued to depend on vorticity formed at the expense of the vehicle kinetic energy, thus requiring work by thrust. Different mixing strategies are discussed and shown to depend also on mechanisms forming vorticity when the regime is compressible. Supersonic combustion is briefly analyzed and found, at sufficiently high combustor Mach, to take place locally at constant volume, unlike conventional Brayton cycles.

Parametric Research and Aerodynamic Characteristic of a Two-Stage Transonic Compressor for a Turbine Based Combined Cycle Engine

“…Recently, the high Mach number engine has become one of the most important research directions in aerospace for application in hypersonic aircraft, considered as the long-term future of long-range aviation [1,2], and has attracted lots of research interests [3][4][5][6]. The turbine-based combined cycle engine (TBCC) is a suitable propulsion power for high Mach number aircraft, which is able to provide wide Mach number operation range, reusability, flexibility and horizontal take-off and landing ability [7].…”

The investigation of inclined AFT wall cavities in a circular scramjet combustor

“…An optimized combustor geometry is therefore needed to address the above-mentioned criticalities. 2,3 In references, [4][5][6] it is clarified that the streamwise vorticity within the combustor enhances the fuel-air mixing. The differences in pressure, density, and velocity are sufficient to develop the streamlined vorticity which improves supersonic mixing and promotes combustion efficiency.…”

“…4 In recent years, cavities have drawn much attention as flame stabilizing devices. [6][7][8][9] The integration of cavities in supersonic combustors not only improves the flame holding but also provides suitable injection schemes and locations. The presence of the cavity induces oscillations that improve the fuelair mixing and consequently the flame anchoring in supersonic reacting flows.…”