Effect of the multiphase composition in a premixed fuel–air stream on wedge-induced oblique detonation stabilisation

Abstract

An oblique detonation wave in two-phase kerosene–air mixtures over a wedge is numerically studied for the first time. The features of initiation and stabilisation of the two-phase oblique detonation are emphasised, and they are different from those in previous studies on single-phase gaseous detonation. The gas–droplet reacting flow system is solved by means of a hybrid Eulerian–Lagrangian method. The two-way coupling for the interphase interactions is carefully considered using a particle-in-cell model. For discretisation of the governing equations of the gas phase, a WENO-CU6 scheme (Hu et al., J. Comput. Phys., vol. 229 (23), 2010, pp. 8952–8965) and a sixth-order compact scheme are employed for the convective terms and the diffusive terms, respectively. The inflow parameters are chosen properly from real flight conditions. The fuel vapour, droplets and their mixture are taken as the fuel in homogeneous streams with a stoichiometric ratio, respectively. The effects of evaporating droplets and initial droplet size on the initiation, transition from oblique shock to detonation and stabilisation are elucidated. The two-phase oblique detonation wave is stabilised from the oblique shock wave induced by the wedge. As the mass flow rate of droplets increases, a shift from a smooth transition with a curved shock to an abrupt one with a multi-wave point is found, and the initiation length of the oblique detonation increases, which is associated with the increase of the transition pressure. By increasing the initial droplet size, a smooth transition pattern is observed, even if the equivalence ratio remains constant, and the transition pressure decreases. The factor responsible is incomplete evaporation before the detonation fronts, which results in a complicated flame structure, including regimes of formation of oblique detonation, evaporative cooling of droplets and post-detonation reaction.

Morphology of oblique detonation waves in a stoichiometric hydrogen–air mixture

“…of providing almost complete premixing of fuel with air at supersonic speeds have been proposed and analysed in a number of studies (Cambier, Adelman & Menees 1990;Menees et al 1991;Valorani, Di Giacinto & Buongiorno 2001;Alexander, Sislian & Parent 2006). For liquid fuels, the complexity of multiphase flows presents also another hurdle (Ren et al 2018(Ren et al , 2019b. Considering that there are several multi-physics affected by a number of gas-dynamic and geometric parameters, which is hard to be determined because there are no referential engines so far, the injection process is thus not modelled here.…”

Mechanisms of the destabilized Mach reflection of inviscid oblique detonation waves before an expansion corner

“…Rather, following the simplification of the inflow of the ODE combustor in previous studies (Ren et al. 2018; Fang et al. 2019; Xiang et al.…”

“…Since this study focuses on the effects of reflection on the stabilization characteristics of ODWs in a space-confined ODE combustor and the relevant inherent mechanisms of stabilization/destabilization, the complex processes of fuel (H 2 ) injection and its subsequent mixing with air in the ODE inlet are not considered here. Rather, following the simplification of the inflow of the ODE combustor in previous studies (Ren et al 2018;Fang et al 2019;Xiang et al 2019), the free stream of the high-altitude atmosphere is assumed to be precompressed twice by two weak OSWs generated by the two 12.5°ramps in the inlet (see figure 1a), and the injection of H 2 and its subsequent mixing with air are assumed to be completed downstream of these two OSWs and before entering the ODE combustor. Consequently, a uniformly premixed stoichiometric H 2 -air inflow is assumed to enter the combustor parallel to the end of the inlet and the wall before the expansion corner (i.e.…”

Review on the Rotating Detonation Engine and It’s Typical Problems

“…The energy conservation for the air-breathing hypersonic aircraft is usually achieved by supersonic combustion. Oblique detonation wave (ODW) is a kind of detonation formed as a reactive mixture flows onto a solid body at a supersonic speed usually exceeding its Chapman-jouguet (C-j) value [24][25][26][27][28], and the standing detonation wave on the solid body has been studied extensively as a potential power source for conceptual hypersonic propulsion technologies such as standing detonation engine (SDE) or oblique detonation wave engine (ODWE). This kind of propulsion system inherits the advantages of the scramjet (supersonic combustion ramjet), and furthermore achieves the high thermal q. XIE, z. jI, H. WEN, z. REN, P. WOlANSkI AND B. WANg cycle efficiency through detonation.…”