Zhaoxin Ren

Swansea University | SWAN · Zienkiewicz Centre for Computational Engineering

The transition structures and wave stabilization features of the wedge-induced oblique detonation wave (ODW) affect the combustion of the hypersonic air-breathing detonation engine, which is associated with the inhomogeneity of the inflow mixture. This study numerically investigates the influence of inhomogeneous kerosene–air mixtures on the stabil...

Industries across the world are making the transition to net-zero carbon emissions, as government policies and strategies are proposed to mitigate the impact of climate change on the planet. As a result, the use of hydrogen as an energy source is becoming an increasingly popular field of research, particularly in the aviation sector, where an alter...

Rotating detonation engine (RDE) with pressure gain is innovative for propulsion. To evaluate the RDE using liquid fuel, the rotating detonation wave (RDW) with kerosene droplets is numerically studied. The Eulerian–Lagrangian two-phase flow model is applied to predict the propagation features of the RDW and the quenching phenomenon. A hybrid WENO...

The anticipated upscaling of hydrogen energy applications will involve the storage and transport of hydrogen at cryogenic conditions. Understanding the potential hazard arising from leaks in high-pressure cryogenic storage is needed to improve hydrogen safety. The manuscript reports a series of numerical simulations with detailed chemistry for the...

The present investigation numerically studies the wedge-induced oblique detonation waves (ODWs) in unsteady inflows with fluctuating fuel–air equivalence ratios. The Navier–Stokes equations with a two-step chemical reaction scheme are solved for modeling the reacting flow. The inflow is introduced with a continuous sinusoidal disturbance of the equ...

Kerosene/air two-phase rotating detonation is numerically investigated to find out the limits of detonation stability as a function of total pressure and total temperature considering the operation conditions of the detonation engine. The Eulerian-Lagrangian two-phase governing system is used and the kerosene/air two-step reaction mechanism is appl...

The oblique detonation wave (ODW) induced by a wedge in the supersonic pre-evaporated kerosene-air flow is investigated via the numerical simulation based on the Navier-Stokes equations with a two-step reaction model. The unsteady inflow feature is subject to a continuous sinusoid pressure disturbance. The influence of oscillating amplitudes and di...

This research addresses a numerical analysis on the effects of flow compressibility on the characteristics of droplet dispersion, evaporation, and mixing of fuel and air according to the simulation of the spatially developing supersonic shear flows laden with evaporating n-decane droplets. A sixth-order hybrid WENO numerical scheme is employed for...

The initiation and stabilization features of oblique detonation wave (ODW) in kerosene-air premixing flows are investigated numerically based on the Navier-Stokes equations with a two-step reaction model. The effects of fuel-air equivalence ratios and inflow Mach numbers are considered by a parametric study. The present results indicate that the de...

Detonation is a promising combustion mode to improve engine performance, increase combustion efficiency, reduce emissions, and enhance thermal cycle efficiency. Over the last decade, significant progress has been made towards the applications of detonation mode in engines, such as standing detonation engine (SDE), Pulse detonation engine (PDE) and...

High-resolution direct numerical simulations are conducted for under-expanded cryogenic hydrogen gas jets to characterize the nearfield flow physics. The basic flow features and jet dynamics are analyzed in detail, revealing the existence of four stages during early jet development, namely, (a) initial penetration, (b) establishment of near-nozzle...

To broaden its’ effective frequency range and to improve its transmission loss performance, a modified design of a Helmholtz resonator is proposed and evaluated by implementing a rigid baffle in its cavity. Comparison is then made between the proposed design and the conventional one by considering a rectangular duct with the resonator implemented i...

The gas-liquid two-phase interfacial flow widely occurs in atomization or liquid film cooling in the field of aerospace engineering. In this paper, the gas-liquid two-phase shear layer is simulated using volume of fraction method by numerical solver Gerris. Both the two-phase interface morphology and growth of the shear layer show a good agreement...

Numerical studies of droplet-laden spatially developing shear layers are conducted with a high convective Mach number (Mc = 1.0), in which a high-order hybrid weighted essentially nonoscillatory scheme is used for the turbulence as well as shock capturing. The evaporating droplets are tracked as point mass in the Lagrangian manner, and the two-way...

Supersonic spray combustion is one of the most significant physiochemical processes that occurs in the scramjet propulsion system, and related research can motivate the development of scramjet engines. This paper reviews the research on supersonic spray combustion that has been conducted in the past few decades and focuses on the key physiochemical...

Numerical simulations are performed to analyze the dynamics of spray flame in a high convective Mach number mixing layer laden with n-decane droplets. The multi-phase reacting flow system is solved by a hybrid Eulerian-Lagrangian model, in which the supersonic mixing layer is mimicked by means of direct numerical simulation and the individual dropl...

The oblique detonation wave in two-phase kerosene-air mixtures over a wedge is numerically studied. The gas-droplet reacting flow system is solved by means of a hybrid Eulerian-Lagrangian method. We elucidate the initiation feature of the two-phase oblique detonation. The effects of the spray equivalence ratio on the initiation characteristics of a...

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 solve...

Numerical simulation is applied to detail the combustion characteristics of n-decane sprays in the highly compressible vortices formed in a supersonic mixing layer. The multi-phase reacting flow is modeled, in which the shear flow is solved Eulerianly by means of direct numerical simulation, and the motions of individual sub-grid point-mass fuel dr...

The characteristics of supersonic cavity flows were investigated using large eddy simulation together with the acoustic analogy method. A fifth-order hybrid compact-weighted essentially non-oscillatory scheme was applied to calculate the convective flux, and a sixth-order compact scheme was used for the viscous flux. Farassat's Formula 1A was used...

The analysis on the interactions of a large-scale shearing vortex, an incident oblique shock wave, and a chemical reaction in a planar shear layer is performed by numerical simulations. The reacting flows are obtained by directly solving the multi-species Navier-Stokes equations in the Eulerian frame, and the motions of individual point-mass fuel d...

A high-speed droplet-laden reacting shear layer is modeled numerically to analyze the dynamics of flame kernel for better understanding ignition and extinction processes in spray combustion. The droplet-laden shear layer, separating a hot-air stream from a monodisperse spray-laden air stream, is modeled by the Eulerian-Lagrangian approach, in which...

The experimental study of hydrogen-air detonation was performed in a 6.3-m-long circular cross-section tube, the rear section of which was walled by silicone or aerogel material. Mixtures of 25% or 29.6% hydrogen with air by volume with an initial pressure of 0.1 MPa and temperature of 293 K were used in the experiments. A short Shchelkin spiral wa...

The triple asteroid system 216 Kleopatra in the main-belt is consisted of the primary 216 Kleopatra and two moonlets Alexhelios [S/2008(216) 1] as well as Cleoselene [S/2008 (216) 2]. The primary is a contact binary asteroid which has highly irregular irregular shape and looks like a dumbbell, its three-axes lengths are 217 × 94 × 81km. Alexhelios...

The dispersion characteristic of particles in the spatial development supersonic coherent vortex was investigated by large eddy simulation coupled with the point-particle Lagrangian trajectory model. The results showed that particles with a specific scale had the strongest dispersion ability. Particles preferentially accumulated in the low speed re...

In this article, three stochastic separated flow models were applied to predict the dispersion of inertial fuel particles in the supersonic turbulent flows. The flow field of continuous phase was simulated by means of Reynolds-averaged Navier-Stokes method with a two-equation turbulence model. Clift's expression was used to modify the drag force on...

In this paper, a two-dimensional (2D) numerical simulation of supersonic reacting shear layer flow laden with evaporating liquid fuel (n-decane) droplets is investigated. The spatial development shear layer is formed by two parallel air streams, uniformly laden with fuel droplets at a narrow region of the inlet. The gas-phase is governed by the com...

To study the response of dispersed droplets to shock waves in the mixing layer flows, the large eddy simulation coupled with particle Lagrangian tracking model was employed to numerically simulate supersonic droplet-laden mixing layer flows. The most instability wave flow disturbances were added to the free streams to stimulate developments of the...

The response of dispersed droplets to oblique shock waves in the supersonic mixing layer was investigated using the large eddy simulation coupled with the particle Lagrangian tracking model. The generated disturbances based on the most-unstable wave model were imposed to excite the development of supersonic shear layer. The oblique shock wave was n...

Under the background of dual combustor ramjet (DCR), a numerical investigation of supersonic mixing layer was launched, focused on the mixing enhancement method of applying baffles with different geometric configurations. Large eddy simulation with high order schemes, containing a fifth-order hybrid WENO compact scheme for the convective flux and s...

The free molecule point source and Simons models coupled to the particle Lagrangian trajectory model are employed, respectively, to establish the fast solving method for gas-particle two-phase vacuum plumes. Density, velocity and temperature distributions of gas phase, and velocity and temperature of particles are solved to present the flow propert...

In this paper, stochastic separation flow (SSF) models were applied to simulate supersonic particle-laden turbulent flows. The statistical flow field of a supersonic spatially developing boundary layer was supplied by a DNS database. The discrete particles were released continuously from a round hole on the boundary into the mainstream and tracked...

To study the dispersion of fuel droplets in the supersonic flow and reveal the momentum and heat exchanges between two phases, a large eddy simulation (LES) and particle Lagrangian tracking model were employed to numerically simulate two-phase mixing layer flows, using the one-way coupling method. The velocity fluctuation disturbances were added to...