Characterization of induction and transition methods of oblique detonation waves over dual-angle wedge

摘要

The oblique detonation wave (ODW) induction and initiation lengths can be reduced significantly by the use of a dual-angle wedge with two subsequent, high and low, angles. In this study, the dual-angle wedge is deflected to different angles at different positions along the wedge and the resulting effects on the shock-to-detonation transition are observed. One-dimensional analytical modeling of flow conservation equations with finite-rate multi-step reaction is carried-out to obtain reactive flow properties over plain and dual-angle wedges. Numerical study was carried out in OpenFOAM to observe the induction and shock-to-detonation transition characteristics. Two different transition mechanisms were observed over dual-angle wedges. The first is an abrupt-type transition from an oblique shock wave (OSW). While the second mechanism involves a brief induction process followed by an intermediate span of shock-induced combustion, which leads to a smooth transition into an ODW. The ODW is formed over the second wedge-angle in both cases. The ODW induction and initiation lengths can be reduced significantly by initially inclining the wedge at a higher angle over only a very short span of the wedge. The second wedge-angle primarily affects the ODW initiation length and downstream flow properties. The position of wedge deflection was identified as a critical geometric parameter which can affect the ODW induction, transition and formation properties. (C) 2018 Elsevier Masson SAS. All rights reserved.