Bing Wang

The dynamics of cavitation bubbles near the wedge region between the free surface and solid wall were experimentally studied using a high-speed camera. In the experiments, the wedge region had different angles θ depending on the solid surface's hydrophobicity. Additionally, the standoff distances of the bubble-solid wall (λw) and bubble-free surfac...

The parameter influence on the wall heat flux of the kerosene two-phase Rotating Detonation Combustor (RDC) are experimentally investigated, and the wall heat flux calculation model of RDC is established based on theoretical analysis and experimental results. Firstly, the characteristics of the wall heat flux distribution of the RDC are obtained by...

Thermoacoustic instability is a persistent problem frequently observed in various types of combustors, resulting in damaging consequences. However, our understanding of the dynamics in industrial combustors undergoing thermoacoustic instability, particularly in solid rocket motors, still remains limited. Data-driven precursors for thermoacoustic in...

A combined computational/experimental study is performed to investigate hypersonic low-density internal gas flows in a convergent-divergent nozzle over a wide range of Knudsen numbers. The numerical solutions are obtained using the direct simulation Monte Carlo (DSMC) method and the experimental measurement is conducted in the hypersonic low-densit...

The wave dynamics play a crucial role in the operation characteristics of the rotating detonation engine. We conducted numerical simulations of a rotating detonation combustor (RDC) using multicomponent reactive Navier–Stokes equations coupled with a discrete phases model. The RDC in this research employs a configuration with multiple coaxial injec...

In this paper, the interaction characteristics between the gaseous detonation and the water droplet are numerically investigated, utilizing a modified compressible two-phase flow model coupling with detailed hydrogen-oxygen chemistry. Firstly, an analysis is conducted on the propagation behaviors of the cellular detonation obstructed by the droplet...

This study investigates the effect of a rotating gliding discharge on synthetic biogas combustion at atmospheric pressure. Synthetic biogas was produced by mixing methane and carbon dioxide. Three mixtures were considered: 100%-0%, 70%-30%, and 50%-50% of methane and carbon dioxide, respectively. The plasma effect was investigated in a low-swirl-nu...

In the present study, an enhanced compressible two-phase flow model is advanced, considering the effect of chemical reactions within a detailed mechanism. In this model, two immiscible fluids (liquid and gaseous mixture) are accurately separated with the resolved interface. Unlike the classical five-equation two-phase flow model, the thermal proper...

Thermoacoustic instability (TAI) has consistently presented challenges to the development of solid rocket motors (SRMs), making the prediction of TAI critically important. Most existing TAI predictions rely on linear instability theory, which is inadequate for predicting certain nonlinear TAI, such as triggered TAI. To address this challenge, this...

A comprehensive numerical study is performed to investigate gas flows inside the inlet of the atmosphere-breathing electric propulsion system using the direct simulation Monte Carlo method. The effects of inlet geometries and gas–surface interaction (GSI) accommodation coefficients on gas pressure and flow rate are analyzed in depth, and a comprehe...

Hopf bifurcation, a prevalent phenomenon in solid rocket motors (SRMs), signifies a critical transition from a fixed point to a limit cycle. The detection of early warning signals (EWSs) for Hopf bifurcation is significant for preventing or mitigating potentially dangerous self-excited states. However, conventional data-driven EWSs are hindered by...

A comprehensive numerical study is performed to investigate gas flows inside the inlet of an atmosphere-breathing electric propulsion (ABEP) system operating in the upper atmosphere ranging from 120 to 300 km using the direct simulation Monte Carlo method. Gas pressure, mass flux, and aerodynamic drag are analyzed in depth in order to gain a deep u...

Conducting an in-depth study of the characteristics of a two-phase rotating detonation combustor is crucial for developing a new type of air-breathing engine that can be used for wide-range flight. This study established the first full-process air-breathing two-phase rotating detonation numerical combustor, based on published experimental data, usi...

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...

The feasibility of using preheated kerosene and pre-evaporation to assist in liquid kerosene detonation ignition and self-sustaining combustion under near-ramjet limit conditions was investigated. Additionally, the detonation decoupling and self-sustaining mechanisms were analyzed in depth. Owing to the forced heat transfer effect of supersonic flo...

Due to the curvature of the droplet surface, the propagation of transmitted waves is complex inside a droplet impacted by an incident shock wave. The wave converging phenomena inside a two-dimensional water column impacted by different curved shock waves are explored in this paper by means of theoretical ray analysis and high-resolution numerical s...

A numerical study is carried out on the droplet-laden two-phase rotating detonation wave of kerosene/oxygen-enriched air at normal temperature. Two types of combustors without and with the inlet mixing section are constructed to illustrate the effect of inlet mixing section on the combustion characteristics of two-phase rotating detonation wave. In...

To achieve the positive total pressure gain of the aerospace propulsion system is one of the critical issues for the application of rotating detonation. This study conducts a theoretical analysis on the total pressure gain (PG) of a rotating detonation system (RDS) composed of the isolator, anti-backflow zone and detonation combustor, with the syst...

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 propagation characteristics and stability of droplet-laden two-phase rotating detonation waves are studied by theoretical analysis and numerical simulations. The stability criterion of rotating detonation waves is proposed for an annular combustor fueled by liquid kerosene, which combines the pre-evaporation equivalence ratio φpre and a dimensi...

The present paper examines the capability of low swirl flows in stabilizing low calorific value fuels. To such an aim, CO2 gas is used to adjust the reactivity of CH4/air mixtures. The results show that increases in CO2 percentage in the fresh mixture result in shrinking the burner stability map by moving the lean and rich blowout limits toward the...

Recessed gas-centered swirl coaxial (GCSC) injector has been widely applied in the liquid rocket engine (LRE), and its internal flow and atomization have a significant impact on the combustion downstream. The oxygen (gas)-kerosene (liquid) two-phase flow in the recessed chamber of GCSC injectors under the conditions of back pressure of 17 MPa is nu...

In this paper, numerical simulations are carried out to study the propagation characteristics of detonation waves in carbon particle-laden two-phase pyrolysis mixtures consisting of C(s)/H2/CO/CH4/O2/N2. The results show that the hydrodynamic thickness of the detonation waves changes non-monotonically with the carbon particle mass loading ratio and...

A comprehensive numerical study is performed to investigate rarefied hypersonic flows past various non-rectangular cavity configurations using the DSMC method, with the effects of free-stream Mach numbers, high temperature gas effects, and three-dimensional (3-D) effects analysed in depth. The primary objective is to obtain insight into the flow ch...

In this study, flame responses to acoustic disturbances with different frequencies and amplitudes were experimentally investigated in a lean premixed swirl-stabilized combustor operating at different bulk velocities. The total heat release rate fluctuations and spatial CH * chemiluminescence distributions were captured using a photomultiplier tube...

The transient pressure propagation induced by the unsteady but stable rotating detonation combustor can lead to degradation of the compressor performance and stability. In this study, the propagation characteristics of feedback pressure perturbation is firstly investigated based on numerical simulations of internal flows. Then a form of isolator co...

In this study, numerical simulations are carried out by utilizing Eulerian-Lagrangian methods to investigate effects of the inert dispersed particles on the propagation characteristics of the H2/CO/air detonation wave. The results show that the inert particles reduce the temperature and velocity of both dispersed and continuous phases. The particle...

Reducing the footprint of greenhouse gases and nitrogen oxides (NOx) emissions from combustion systems means that they have been operating under lean or ultra-lean fuel–air premixed conditions. Under such conditions, self-excited large-amplitude pulsating thermoacoustic instabilities may occur, characterized by deafening combustion noises and even...

A focusing shock wave can be generated during the high-speed impact of a droplet on a 180 • constrained wall, which can be used to realise energy convergence on a small scale. In this study, to realise high energy convergence and peak pressure amplification, a configuration of droplets embedded with cavities is proposed for high-speed impingement o...

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...

Swirling flows have been widely used to stabilize lean premixed combustion in various gas turbines and furnaces. In such flows, understanding and characterizing the flame stabilization are of both practical and fundamental interests. It is known that the swirling motion decreases the flow velocity at the burner outlet, which contributes to flame st...

In this work, combustion instability of the solid-fueled ramjet (involving diffusion-dominant combustion process) is investigated using a numerical model. Effects of inlet thermodynamic properties, such as inlet temperature Tin, Mach number Ma and mass flow rate m˙a on generating combustion instability are evaluated. The 2-dimensional (2D) model is...

The cavity collapse induced by the shock wave, especially multiple shock waves, is a compressible multiphase problem which contains transient fluid dynamics and complex physical phenomena. As this problem widely exists in many applica-tion fields, for example the spacecraft fuel injection and the extracorporeal shock wave therapy processes, it is n...

This paper performs a numerical study of the droplet impact inside a solid tube with the initial speed of 300 m/s. The comparison of impingement is conducted between the dense droplet and the droplet embedded with different arrangement of cavity lines. The results show that the focus shock wave is generated once the droplet impacts on the bottom of...

Ammonia (NH3), as a carbon-free fuel with a high hydrogen content, has been considered as a promising candidate to be applied for transportation, propulsion, and power generation sectors. However, due to the presence of nitrogen atoms, direct combustion of NH3 features a high NOx emission, which could hinder its wide application. Thus it is importa...

Supersonic mixing layer flows are taken in scramjet engines for enhancing mixing and combustion efficiency. The spatial growth of supersonic reacting mixing layers with streams of dilute hydrogen and air has been investigated using direct numerical simulation, with detailed chemical reaction mechanisms. Different inlet air temperatures are consider...

Unlike hydrocarbon fuel, ammonia is a carbon-free and renewable energy source. It is also regarded as one of the potential energy carriers. However, ammonia combustion for power generation is not well studied under micro-scale conditions, especially concerning nitrogen oxides (NOx) emission. For this, thermal performances and NO emission characteri...

The present work examines the NOx emission characteristics of a premixed micro-combustion system with a perforated plate implemented. For this, a three-dimensional (3D) computational model involving a detailed chemical-kinetic mechanism for ammonia-oxygen combustion in the micro-combustor is developed. The model is first validated with the experime...

In this study, the response of a supercritical round jet to various excitation modes including varicose, helical, flapping, dual varicose/helical and dual varicose/flapping is studied using large eddy simulations. A translation method is proposed to enhance the accuracy of the equation-of-state and transport correlations. Results show that the excita...

In this study, experimental measurements are performed on a swirl-stabilized combustor to study the nonlinear combustor dynamic characteristics under acoustic excitations. The imposed acoustic disturbances with different frequencies and amplitudes generated by a loudspeaker are applied to the combustion system. The acoustic pressure oscillations an...

Comparative evaluation lies at the heart of science, and determining the accuracy of a computational method is crucial for evaluating its potential as well as for guiding future efforts. However, metrics that are typically used have inherent shortcomings when faced with the under-resolved solutions of real-world simulation problems. We show how to...

A comprehensive numerical study is performed to investigate rarefied hypersonic flows past a flat plate with a two- (2D) or three-dimensional (3D) rectangular cavity using the direct simulation Monte Carlo method. In this work, we obtain different boundary-layer thicknesses at the cavity entrance by varying the length of upstream flat plate. Then,...

A configuration is presented for the rotating detonative airbreathing combined cycle engine with compatibility between the turbomachinery and rotating detonation combustor being realized. Two propulsion units are merged to achieve three different operating modes, which provides a favorable propulsion choice for advanced full range and trans-aerosph...

In the present study, high-speed droplet impingement on typical curved surfaces is numerically investigated to analyse the inherent complex wave structures and cavitation. A three-component compressible multi-phase flow model is utilised considering fluid phase transitions, but the calculation of coupling with the solid structure is neglected. A de...

In this work, the dynamics of the pressure oscillations and flame behaviors in a premixed swirl-stabilized combustor were experimentally investigated. As equivalence ratio Φ varied between 0.55 and 1.35, five combustion states were distinguished based on the characteristics of the acoustic pressures and flame dynamics. The permutation entropy (PE)...

A direct simulation Monte Carlo (DSMC) method is utilized to numerically investigate rarefied hypersonic flows over a group of two-dimensional rectangular cavities with rounded separation/reattachment corner. The effects of the rounded separation/reattachment corner on flow characteristics are discussed. The sensitivities of aerodynamic surface qua...

Ammonia (NH 3) is considered as a potential alternative carbon free fuel to reduce greenhouse gas emission to meet the increasingly stringent emission requirements. Co-burning NH 3 and H 2 is an effective way to overcome ammonia's relative low burning velocity. In this work, 3D Reynolds Averaged Navier-Stokes (RANS) numerical simulations are conduc...

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...

Base on the concept of molecular mean free paths in high-altitude rarefied aerodynamics, a novel conceptual lightweight design is proposed and applied to the aerodynamic design of wings of hypersonic vehicles cruising in the upper atmosphere between 120 km to 300 km. The lightweight scheme proposed here is promising in hypersonic vehicles cruising...

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...

The continuous detonation engine (CDE) is based on detonation waves and is a new jet engine concept that is expected to bring a technical revolution to current aviation and aerospace propulsion systems. Some scholars have also called this concept the continuously rotating detonation engine or rotating detonation engine. The advantages and applicati...

In this study, an in-house developed fully compressible solver utilizing high-order numerical discretization schemes is used to study the effects of swirl intensity on thermoacoustic instabilities in a lean premixed swirl stabilized combustor. Turbulent combustion modeling is achieved using large eddy simulations along with dynamically thickened fl...

Acoustic characteristics of a thrust chamber with quarter-wave resonators are numerically studied based on the unsteady Reynolds-averaged Navier-Stokes (URANS) method. Organized pressure disturbance model and constant-volume bomb model are applied as artificial disturbances to excite pressure oscillations in the chamber. Eigenfrequencies and amplit...

The potential advantages of rotating detonation combustion are gradually approved, and it is becoming a stable and controllable energy conversion way adopted to the propulsion devices or ground-engines. This study focuses on the rotating detonation-based turboshaft engine, and the architecture is presented for this form of engine with compatibility...

A numerical investigation is presented for a free-molecular flow past two parallel circular flat plates using the test particle Monte Carlo (TPMC) method, with flow shadowing and multiple reflections analyzed. Flow shadowing and multiple reflections have a significant effect on aerodynamic forces, and the distance-to-radius ratio of the two plates...

To meet stringent NOx emission requirements, lean premixed swirling combustion technology is widely applied in power generation and propulsion systems. However, such combustion systems are more susceptible to nonlinear combustion instability due to the fluid flow-acoustics-combustion interaction. It is typically self-exited and characterized by lar...

This numerical study investigated the effects of the fresh mixture temperature on thermoacoustic instabilities in a lean premixed swirl-stabilized combustion chamber by utilizing high-fidelity, fully compressible large eddy simulations. At low fresh mixture temperatures, the side recirculation zone stabilized the premixed flame on the boundary of t...

This numerical study investigated the effects of the fresh mixture temperature on thermoacoustic instabilities in a lean premixed swirl-stabilized combustion chamber by utilizing high-fidelity, fully compressible large eddy simulations. At low fresh mixture temperatures, the side recirculation zone stabilized the premixed flame on the boundary of t...

The combustion instability has been one of severe problems suffered by solid rocket motors (SRMs) for a long term. This paper proposes a burning rate model utilizing the pressure-coupled response function for description of the spatiotemporal burning of AP-HTPB composite propellant grains in SRMs. The model is successfully incorporated to the axisy...

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...

In the study, the propagation behaviors of rotating detonation are investigated in an obround slit-channel combustor which has four curvature transition sections by employing a H2O2N2 mixture with different oxygen volume fractions (α) and equivalence ratios (ERs). High-frequency pressure sensors are circumferentially mounted into the outer wall to...

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...

A comprehensive numerical calculation has been conducted to investigate a rarefied hypersonic flow past a three-dimensional (3-D) cavity with a length-to-depth ratio of 4 using the direct simulation Monte Carlo (DSMC) method. In this calculation, the representative atmospheric environment at altitudes of 70 km, 75 km, 80 km and 90 km is considered...

The performance analysis of mixed-exhaust turbofan engine with multi-annular rotating detonation duct burner is conducted for the first time, considering that the flow path of the bypass duct is ideal for a rotating detonation combustor. The configuration of the multi-annular rotating detonation combustor is constructed aiming at the advantages of...

In this study, large eddy simulations with dynamically thickened flame combustion model are used to study effects of acoustic excitations on low swirl flow and flame features. Obtained results show that external excitations induce perturbations in swirl number upstream of the flame front, which in turn change the coherent structures and the tempora...

In this study, simultaneous particle image velocimetry and planar laser induced fluorescence of hydroxyl radical, chemiluminescence imaging, and hot-wire measurements are utilized to study reacting low swirl flow dynamics under low to high amplitude acoustic excitations. Results show that a temporal weak recirculation zone exists downstream of the...

In this study, simultaneous particle image velocimetry and planar laser induced fluorescence of hydroxyl radical, chemiluminescence imaging, and hot-wire measurements are utilized to study reacting low swirl flow dynamics under low to high amplitude acoustic excitations. Results show that a temporal weak recirculation zone exists downstream of the...

Occurrences of pulse-triggered instabilities in combustion chambers always trouble solid rocket motors (SRMs) in application. This paper performs numerical simulation of the pulse-triggered nonlinear instabilities in the end-burning-grain SRM, in use of the pressure-coupled response function to describe the spatiotemporal burning rate of AP-HTPB co...

Comparative evaluation lies at the heart of science, and determining the accuracy of a computational method is crucial for evaluating its potential as well as for guiding future efforts. However, metrics that are typically used have inherent shortcomings when faced with the under-resolved solutions of real-world simulation problems. We show how to...

A configuration for a dual-duct rotating detonation aero-turbine engine (DRDATE) is proposed. With the isolator and mixer arranged upstream and downstream from the rotating detonation combustor (RDC) respectively, the compatibility between turbomachinery and RDC can be realized. The conventional single annular RDC is replaced with a multi-annular R...

A comprehensive study on influences of hydrodynamic features of a swirling flow on thermoacoustic instabilities in a swirl stabilized combustor is performed by using large eddy simulations along with the dynamically thickened flame combustion model. The governing equations in full compressible form are solved by an in-house developed high-order num...

The high-speed impingement of hollow droplets embedded with a cavity has fundamental applications in various scenarios, such as in spray coating and biomedical engineering. The impingement dynamics is modulated by the wrapping medium, different from that of denser solid droplets. With air and vapour cavities, the impingement of two kinds of hollow...

The droplet breakup and the bubble collapse are typical flow phenomenon involving complicated pressure and density variation as well as interface evolution. In this paper, the numerical simulation of a planar shock wave interacting with an acentric water ring is studied. In order to simulate the spatiotemporal interface evolution of the water ring...

Fast and accurate prediction for aerodynamic coefficients of satellites in LEO (Low-Earth Orbit) is a fundamental prerequisite for the determination and control of orbit. Based on the test particle Monte Carlo (TPMC) method for the calculation of molecular flux rate through a pipe in vacuum technology, combined with the free-molecular theory, the T...

In this work, we improve a weakly-compressible SPH method which is based on our previous work of Zhang et al. (2017)[30]by employing a weighted essentially non-oscillatory (WENO)reconstruction. The key idea is to construct along each interacting particle pair a 4-point stencil and to apply a WENO reconstruction for determining the particle interact...

: In this work, experimental studies are conducted to measure the aeroacoustics damping performances of 11 in-duct perforated plates in a cold-flow pipe with a variable Mach number. These in-duct plates have the same porosities but different number N and geometric shaped orifices. Here 6 shapes are considered, i.e. 1) triangle, 2) square, 3) pentag...

The wave patterns of shock wave interaction with multi-material interface have been studied in the past decades. Interactions between shock waves and interfaces can be classified as slow-fast and fast-slow case depending on the relative acoustic impedance of two mediums as shock passes from one to another. In this paper, the fast-slow case of shock...

A lower combustor inlet Mach number is desirable in order to design a compact, lightweight combustor and boost the overall performance of the scramjet engine. In this study, a thrust control strategy is proposed for a hydrogen-fueled scramjet taking into account the operating limitations, which is called the minimum combustor inlet Mach number rule...

The interaction of a weak shock wave with a heavy elliptic gas cylinder is investigated by solving the Eulerian equations in two-dimensional Cartesian coordinates. An interface-capturing algorithm based on the \(\gamma \)-model and the finite volume weighed essential non-oscillatory scheme is employed to trace the motion of the discontinuous interf...

Many practical lean-premixed combustion systems involved in land-based power plants, gas turbines and boilers are susceptible to self-excited combustion instability, which is characterized by detrimental periodic pressure oscillations. Little attention has been paid on experimentally characterizing the chemical emissions and thermodynamic propertie...