Numerical modelling of oblique shock and detonation waves induced in a wedged channel

Abstract

A computational study of wedge-induced oblique shock and detonation wave phenomena in the flow of a combustible mixture over a wedged channel is presented with the purpose of understanding the fundamental gasdynamics of the waves and their interactions. A two-dimensional, time accurate, finite-volume-based method was used to perform the computations, and a five-species, two-step chemical reaction is assumed for a stoichiometric hydrogen-air mixture. The combustion channel is made of a wedged section followed by a constant area section. The simulation was performed with wedges of up to 20 • semi-angle and Mach numbers from 1.25 to 6, with other inflow parameters fixed. Within the computational domain either propagating or standing shock and detonation wave configurations were obtained depending on the flow Mach number and the wedge semi-angle. Four flow modes, namely, a propagating detonation wave, a standing detonation wave, a propagating shock wave, and a standing shock wave mode were identified. The two detonation-based modes were emphasized. Detonation initiation, propagation, and the induced wave interactions of these modes were investigated. The shock-based modes were also studied briefly. Phenomena explored included overall wave structures, detonation initiation arising from shock coalescence, location of initiation, and double detonation initiation. The physical mechanisms of these phenomena were analysed.

Numerical study of inflow equivalence ratio inhomogeneity on oblique detonation formation in hydrogen–air mixtures

“…The fine scale, instability features on the oblique detonation surfaces with sets of transverse waves are typical of an unstable frontal structure of normal cellular detonations [18][19][20][21][22]. Furthermore, multi-mode detonation engines which combine the potential advantage of both ODW and the pulsed normal detonation [23,24] are proposed, and the ODW induced by a confined wedge is also analyzed numerically and theoretically [25,26].…”

Transition Between Different Initiation Structures of Wedge-Induced Oblique Detonations

“…F OR a supersonic combustible gas flow past a wedge, depending on the incoming flow condition and the wedge angle, an oblique shock wave (OSW) is attached to the wedge and may trigger the formation of an oblique detonation wave (ODW). The idea of harnessing a standing ODW for hypersonic airbreathing propulsion systems has long been considered and is still under investigation [1][2][3][4]. Although many theoretical investigations have provided the basic foundation for steady ODWs [5][6][7][8], the current research on ODW phenomenon has been toward attaining a better fundamental understanding of its transient formation structure and stability.…”

Review on the Recent Development of Multi-mode Combined Detonation Engine

“…The American researchers Fan and Lu [34] from University of Texas at Arlington, numerical studied the oblique shock and detonation waves induce in a wedge channel in a stoichiometric H 2 /air mixture. The simulation was performed with the wedges of up to 20°, semiangle and Mach number from 1.25 to 6.…”