THEORICAL STUDY ON PROPULSIVE PERFORMANCE OF OBLIQUE DETONATION ENGINE

Abstract

Detonation combustion is characterized by the high thermodynamic efficiency and fast heat release. Benefitting from these potential advantages, an oblique detonation wave (ODW) is introduced into the combustion chamber and oblique detonation engine (ODE) plays an important role in hypersonic air-breathing propulsion systems. Previous studies mainly focused on the initiation structures, standing features and wave systems of oblique detonation, but the global analysis of ODE propulsive performance is still absent at the macro-level. In this paper, the flow and combustion processes of an ODE are decomposed into four basic modules, named as inlet model, mixing model, combustion mode and nozzle model, respectively. We solve these four basic flow processes using theoretical methods and propose a systematically theoretical approach that can be used to predict the ODE propulsion performance. On the basis of previous ODW initiation structures and waves systems, four different combustion modes, i.e., over-driven ODW, Chapman-Jouguet ODW, over-driven normal detonation wave and oblique shock-induced constant-volume combustion, are chosen to describe the heat release processes of combustible mixture in the ODE combustor. The effects of different combustion modes on fuel specific impulse of the ODE are also analyzed. In addition, the influence mechanisms of inflow parameters, combustor parameters and intake-exhaust parameters on the thrust performance of ODE are also obtained, and the results show that the major factor of fuel specific impulse of an ODE consists mainly of the inflow Mach number and the expansion ratio of engine nozzle. Finally, combined with precious detonation research results, such as the standing features and initiation structures of oblique detonation in a confined space, the preliminary design direction of oblique detonation engine are proposed, which mainly involve some constrained conditions, such as geometrical constraints, inflow velocity limitations and stability ranges of a detonation wave in ODE combustor.