An a priori assessment of the disparities in estimating the filtered chemical reaction rates in Large-Eddy Simulations (LES) is performed using two Direct Numerical Simulations (DNS) of turbulent premixed flames. DNS of turbulent premixed flames with the same turbulent Reynolds number but different Karlovitz numbers are carried out using semi-detailed finite-rate chemistry to represent different flame

Large Eddy Simulation (LES) of the lab-scale methane fire plumes investigated experimentally by McCaffrey is performed using the steady laminar flamelet/presumed beta filtered density function model on grids of different resolution ranging from the Taylor length scale to about six times the Kolmogorov length scale. This work focuses on investigating existing subgrid (SGS) mixing models for mixture

This paper presents numerical and asymptotic analytical solutions for the current–voltage characteristic of a flame using a one-dimensional ion transport model with boundary conditions that include detailed treatment of sheath formation. Non-dimensional conservation equations are presented for the free electron, the hydronium ion, and the electrical potential in a one-dimensional flow field with uniform

The objective of this study is to bring fundamental information on the coupling between combustion and thermal radiation occurring at flame scale. The study considers a simplified configuration corresponding to one-dimensional counterflow planar laminar diffusion flames subjected to time-evolving moderate-to-slow mixing conditions that are representative of fires. The flame simulations are performed

This study presents careful measurements from lab-scale experiments and predictions from comprehensive numerical model for the burning characteristics of laminar flames over MMA pools of different diameters with varying ullages or lip heights. Lab-scale experiments for steady burning of MMA pool are conducted, and temperature and concentrations of major species, have been measured for 3 mm ullage case

A series of two dimensional (2D) detailed numerical simulations of premixed cylindrical expanding ethanol/air flames in a constant volume encloser under elevated pressures and equivalence ratios are performed to investigate cellular flame instability. The results demonstrate that at pressure of 10 atm and temperature of 358 K, ethanol/air flame cellular instability increases non-monotonically with

Continuation computations were performed to generate the S-curve as well as the flammability limit. Transient simulations using detailed fuel chemistry and transport models were conducted to reproduce the oscillatory extinction process. It was found that the cool spherical diffusion flame (SDF) had a much extended extinction limit than the hot SDF. The cool SDF with double-reaction-zone structure had

Due to the increasing attention of low temperature combustion, more precise and convenient low temperature chemical reaction mechanism is needed in the combustion reaction flow modelling. However, most of the conventional mechanism reduction methods are difficult to deal with the low temperature mechanism. In order to reduce the low temperature combustion mechanisms of hydrocarbon fuel efficiently

Shuttle kilns are widely used in the sanitary ware industry. A key parameter to reduce energy consumption and increase their overall performance is temperature uniformity. Therefore, in this paper a systematic and statistical study of the effect of the position of burners and their interactions on the temperature uniformity of a shuttle kiln is performed. CFD simulations and a 4k factorial analysis

Flame front identification and analysis in premixed turbulent combustion often relies on some scalar iso-surface as a flame marker, and the quest for a suitable scalar, and an appropriate flame-identifying iso-value, then becomes important. In an effort to contribute to this field, we study the suitability of various flame front identification approaches using the concept of ridge analysis. This serves

An analysis is presented for the Burke–Schumann flame established when a fuel tank discharges with mean velocity U along a circular duct of radius a filled initially with air. Attention is focused on effects of interactions of shear with transverse diffusion resulting in enhanced longitudinal dispersion. The analysis accounts for preferential-diffusion effects arising for non-unity values of the fuel

In this work we investigate the linear stability of combustion waves propagating in a system of two layers of different exothermic reacting materials under conditions of thermal contact between them through the common interface using the reaction sheet approximation. The dispersion relations are found and the dependence of the stability boundary on the parameters of the model is studied. It is demonstrated

Experimental data and detailed numerical modelling are presented on the burning characteristics of a model gasoline/biofuel mixture consisting of n-heptane and iso-butanol. A droplet burning in an environment that minimises the influence of buoyant and forced convective flows in the standard atmosphere is used to promote one-dimensional gas transport to facilitate numerical modelling of the droplet

A three-dimensional Direct Numerical Simulation (DNS) database of statistically planar turbulent premixed flames covering the wrinkled/corrugated flamelets and the thin reaction zones regimes of premixed turbulent combustion has been utilised to assess the performances of the extrapolation relations, which approximate the stretch rate and curvature dependences of density-weighted displacement speed

In this paper, the flame characteristics of co-axial concomitant flow diffusion combustion of low calorific value gas under the action of thermal dynamics are studied. Based on Fluent software, the combustion process of low calorific value gas is simulated by a finite element volume method. According to different air preheating temperatures T a i n , by analyzing the changes of temperature field, velocity

A flamelet model is applied to the simulation of axisymmetric counterflow laminar flames including gravitational acceleration and the geometrical details of main nozzles and annular shrouds. The flamelet chemistry model consists of two mixture fractions and is found to be very accurate when compared to results obtained with finite rate chemistry and mixture-average transport. Steady and unsteady solvers

A flamelet model is applied to the simulation of axisymmetric counterflow laminar flames including gravitational acceleration and the geometrical details of main nozzles and annular shrouds. The flamelet chemistry model consists of two mixture fractions and is found to be very accurate when compared to results obtained with finite rate chemistry and mixture-average transport. Steady and unsteady solvers

Laminar flame speed (LFS) is one of the most important physicochemical properties of a combustible mixture. At normal and elevated temperatures and pressures, LFS can be measured using propagating spherical flames in a closed chamber. LFS is also used in certain turbulent premixed flame modelling for combustion in spark ignition engines. Inside the closed chamber or engine, transient pressure rise

A reduced order kinetic model for NO (nitric oxide) prediction, based on the virtual chemistry methodology [M. Cailler, N. Darabiha, and B. Fiorina, Development of a virtual optimized chemistry method. Application to hydrocarbon/air combustion, Combust. Flame 211 (2020), pp. 281–302], is developed and applied. Virtual chemistry aims to optimise thermochemical properties and kinetic rate parameters

A model is developed for the formation and propagation of cracks in a material sample that is heated at its top surface, pyrolyses, and then thermally degrades to form char. In this work the sample is heated uniformly over its entire top surface by a hypothetical flame (a heat source). The pyrolysis mechanism is described by a one-step overall reaction that is dependent nonlinearly on the temperature

A reduced order kinetic model for NO (nitric oxide) prediction, based on the virtual chemistry methodology [M. Cailler, N. Darabiha, and B. Fiorina, Development of a virtual optimized chemistry method. Application to hydrocarbon/air combustion, Combust. Flame 211 (2020), pp. 281–302], is developed and applied. Virtual chemistry aims to optimise thermochemical properties and kinetic rate parameters

In this paper, the Heterogeneous Quasi 1-D model for steady combustion of AP–HTPB propellants is extended to the unsteady regime. The extended model is used to calculate the pressure-coupled frequency response ( R p ) of low-smoke (non-aluminised) multi-modal AP–HTPB propellants. The R p of a multi-modal propellant is expressed in terms of that of the individual binder-matrix coated AP particles constituting

Radiative heat transfer plays an important role in the chemical reactions in the combustor. The widely used WSGG model proposed by Smith is established for normal pressure, which shows inevitable computational errors when dealing with radiative heat transfer problems at reduced or elevated pressures. In this paper, an improved global model is established to calculate the radiant energy exchanges between

In this study, mixed fuel droplets of ethyl alcohol and biodiesel with different volumes or ratios were prepared and the related expansion, injection and micro-explosion phenomena were investigated. During the tests, a mixed-fuel droplet was hung on a high-temperature-resistant Cr-Ni wire, which was transported to the preheating piston for heating and then was ignited automatically. Micro-needles and

In this study, mixed fuel droplets of ethyl alcohol and biodiesel with different volumes or ratios were prepared and the related expansion, injection and micro-explosion phenomena were investigated. During the tests, a mixed-fuel droplet was hung on a high-temperature-resistant Cr-Ni wire, which was transported to the preheating piston for heating and then was ignited automatically. Micro-needles and

In this work, a quasi-one-dimensional ZND model of detonation considering the expansion process perpendicular to the detonation propagation direction is extended to the rotating detonation engine (RDE) to investigate the influence of expansion on the detonation waves in RDEs. This model is first used in more general cases of one-dimensional detonation waves, coupled with the one- and two-step kinetic

We investigate a model of solid propellant combustion involving surface pyrolysis coupled to finite activation energy gas-phase combustion. Existence and uniqueness of a travelling wave solution are established by extending dynamical system tools classically used for premixed flames, dealing with the additional difficulty arising from the surface regression and pyrolysis. An efficient shooting method

A novel combustion modelling approach is proposed here to study the transient effects of diesel spray. Conditional Source-term Estimation (CSE) is a combustion model which invokes the Conditional Moment Closure (CMC) hypothesis to provide an approximation of the mean chemical source term in an averaged transport equation. Unlike CMC, where transport equations are solved for conditional moments, CSE

The Sydney piloted partially premixed flames with both homogeneous and inhomogeneous fuel/air inlets are studied using a dynamic second-order moment closure model in the framework of large eddy simulation with a four-step global reaction mechanism. The filtered reaction rates are directly closed using the second-order correlation moments of reactive scalars. Good agreements between LES and experimental

In this paper, the effect of geometry on the dynamics of the hydrogen–air flame stabilised on the surface of a burner is investigated numerically. Two main regimes of combustion front stabilisation near the cylindrical burner: attached and detached flames are investigated and compared to the planar case. The neutral stability boundary for diffusive-thermal instability is studied in detail. The attached

In recent years, attention has been focused on the use of porous materials to enhance the efficiency of combustion systems and reduce the pollutants emission. However, the porous media burners have the problem of inclined flame when used for surface heat treatments. In order to solve this problem, a new structure of porous media burner with pores step distribution in radial direction is proposed in

The dynamic behaviour and structures of laminar counterflow diffusion methane flames under oscillatory strain rates are investigated based on both detailed and reduced chemistry. It is known both from experiment and numerical studies that flame can deviate from its quasi-steady manner for high frequencies, which makes the well-known steady laminar flamelet model questionable. In this work, the Reaction-diffusion

Spherical flame initiation and propagation in particle-laden mixtures are investigated theoretically in this work. Within the framework of constant density, large activation energy and quasi-steady assumptions, a correlation describing spherical flame propagation speed as a function of flame radius is derived. This correlation is used to assess the influence of gas and particle properties on initiation

Turbulence-radiation interactions are studied in this work for large-eddy simulations (LES) of an artificially scaled configuration based on the Sydney bluff-body burner. This investigation is performed by applying the combustion model flamelet generated manifolds, and the transported PDF Eulerian stochastic field method is employed to account for turbulence-chemistry interaction. The radiative transfer

This study investigates the formation and evolution of soot and NO X in a high-pressure constant-volume combustion chamber. This work focuses on the effect of multiphase thermal radiation and O2 dilution in ambient/exhaust gases, sometimes also referred to as exhaust gas recirculation (EGR), qualitatively and quantitatively. The spray-A case (n-dodecane as fuel) from Engine Combustion Network (ECN)

This paper presents CFD modelling of hydrogen-air deflagrations. The proposed mathematical models are validated with the experiments provided to SARNET2 (Severe Accident Research NETwork of Excellence 2) project [A. Bentaib, A. Bleyer, N. Chaumeix, B. Schramm, P. Kostka, M. Movahed, H.S. Kang and M. Povilaitis, Final results of the SARNET Hydrogen deflagration Benchmark Effect of turbulence on flame

Freely propagating, one-dimensional, laminar, premixed flames of ethylene–air are analysed at standard temperature and pressure (STP) and at elevated temperature and pressure conditions to reveal the differences in flame structure. For high-temperature and low-pressure conditions, there is a significant contribution to the total heat release in the post-flame region leading to an ambiguity in the definition

The paper analyses the hydrodynamic instability of a flame propagating in the space between two parallel plates in the presence of gas flow. The linear analysis was performed in the framework of a two-dimensional model that describes the averaged gas flow in the space between the plates and the perturbations development of two-dimensional combustion wave. The model includes the parametric dependences

The topic of thermoacoustic instabilities in combustors is well-investigated, as it is important in the field of combustion, primarily in gas-turbine engines. In recent years, much attention has been focused on monitoring, diagnosis, prognosis, and control of high-amplitude pressure oscillations in confined combustion chambers. The Rijke tube is one of the most simple, yet very commonly used, laboratory

In this work, the mathematical modelling of a internal combustion (IC) engine fed with multiple fuels, and a control scheme for controlling the spark timing of the IC engine are presented. The goal of this work is controlling the IC engine spark timing when it is feed with a hydrogen-enriched E10 blend as fuel, without efficiency and torque losses, at different operating points. The importance of controlling

The critical dimension necessary for a flame to propagate in suspensions of fuel particles in oxidiser is studied analytically and numerically. Two types of models are considered: First, a continuum model, wherein the individual particulate sources are not resolved and the heat release is assumed spatially uniform, is solved via conventional finite difference techniques. Second, a discrete source model

The study investigates detonations with multiple quasi-steady velocities that have been observed in the past in systems with multi-peaked thermicity, using Fickett's detonation analogue. A steady-state analysis of the travelling wave predicts multiple states, however, all but the one with the highest velocity develop a singularity after the sonic point. Simulations show singularities are associated

Combustion research still needs more advanced fundamental understanding of combustion chemistry and dynamics from molecule scale to particle. The latter is also needed for soot and nanoparticles formation and combustion system control such as homogeneous charge compression ignition engine, and flame regimes and instability. The complex interactions between hundreds of species linked within thousands

In this paper, we present a systematic roadmap for developing a robust and parallel multi-material reactive hydrodynamic solver that integrates historically stable algorithms with new and current modern methods to solve explosive system design problems. The Ghost Fluid Method and Riemann solvers were used to enforce appropriate interface boundary conditions. Improved performance in terms of computational

(2019). Correction. Combustion Theory and Modelling: Vol. 23, No. 6, pp. 1191-1192.

During the last decades, tabulated chemistry approaches, like manifold-based concepts to implement model reduction, have become a widespread, promising and accurate method to take chemical reactions into account in computing reacting flows. However, there is a number of crucial issues concerning the generation and implementation of the tabulated chemistry approaches. These concern the way manifolds

In the current work, the auto-ignition of a turbulent round methane jet is studied numerically by means of a transported probability density function (PDF) method. The methane jet is issued into a hot, vitiated coflow, where it ignites to form a steady lifted flame. For this flame, experimental data of hydroxyl, temperature and mixture fraction are provided in the area where the fuel auto-ignites.

Due to recent interest in methanol economy, it is seen that a numerical study of combustion of methanol in a comprehensive manner is necessary. Motivated from this interest and based on the studies from literature, a numerical study on prediction of structures of non-premixed methanol-air flames in laminar forced convective environment is reported. Two-dimensional, planar and axisymmetric, computational

In this work, we propose a physics-based scaling theory for the evolution of small-scale turbulence eddies in the unburnt mixture when they travel across the preheat zone of a premixed flame. This scaling theory is developed to explicitly account for the effects of viscous diffusion on the length and velocity scales of turbulence eddies that are smaller than the inner reaction zone thickness of a premixed

This paper introduces a new method to formulate reaction progress variables for the application of FGM in combustion systems. The method involves a multiobjective optimisation to find a reaction progress variable that accurately reproduces complex reactive phenomenon of interest. In our current research, the method is applied to igniting non-premixed flames. The optimised progress variable combinations

A simple model with detailed chemistry for predictions of NO x and CO emission from cylindrical porous burners is proposed on the basis of chemical reactor network concept. Combustion in the inner hollow of the burner is modelled by laminar premixed flame while the processes inside the porous shell are described by zero-dimensional constant pressure perfect stirred reactor. Numerical results on NO

Detonation development inside spark ignition engines can result in the so called super-knock with extremely high pressure oscillation above 200 atm. In this study, numerical simulations of autoignitive reaction front propagation in hydrogen/air mixtures are conducted and the detonation development regime is investigated. A hot spot with linear temperature distribution is used to induce autoignitive

This paper presents a combustion model of a nano-aluminum-air (nAl-air) suspension. The special feature of the model is performing a local mathematical model of the oxidant diffusion through an aluminum oxide layer on the particle surface taking into account the aluminum-oxidant reaction to simulate the combustion of nano-size aluminum (nAl) particles. The oxidation rate of the aluminum particles and

We propose an algorithm for low Mach number reacting flows subjected to electric field that includes the chemical production and transport of charged species. This work is an extension of a multi-implicit spectral deferred correction (MISDC) algorithm designed to advance the conservation equations in time at scales associated with advective transport. The fast and nontrivial interactions of electrons

In this study, the theoretical approach and numerical modelling of coal spontaneous combustion were investigated considering the aging effect. Numerical simulations of three-dimensional coal piles in cubic wire-mesh baskets (WMBs) were performed using ANSYS FLUENT. A theoretical heat generation model was constructed that incorporated aging effect (using a decay-power factor, γ), equivalent oxidation

The low temperature first ignition of n-butane/air mixtures is studied in this work, using a short chemistry model with all the important isomers. The reaction rates were obtained from the published data. The first ignition delay time and the overall heat release (temperature jump) were obtained analytically in closed form, where the parametric influence can be easily seen. The chain branching leading

The production of oxygenated hydrocarbons, hydrogen peroxide, and ethylene by low and intermediate temperature reactions of C1–C3 alkanes in a homogeneous charge compression ignition (HCCI) in an internal combustion engine was explored via single-zone modeling. For lean equivalence ratios, the main operating parameters were successively optimised with respect to intermediate species yield. A combination

Indirect coal combustion can solve some problems such as low efficiency and air pollution during traditional coal combustion, this research investigates energy release characteristics of indirect combustion and aims to achieve maximum energy utilisation. Firstly, Energy Utilization Diagrams Methodology was used to explore exergy cascade release pathways and exergy losses for typical indirect combustion

Traditional way for energy production is coal-fired power plants. Change in coal characteristics would result in change in ash properties (ash fusion temperatures, ash elemental composition) as expected and would finally and possibly result in slagging or fouling problems inside the boiler. The high temperature of combustion process and a low melting point of ash or vice versa might be considered as

The surface regression of burning solid fuels facing a forced flow has been observed and measured by several authors, because of its connection with mass burning rate and heat transfer between flame and fuel. The pyrolysis region of non-spreading flames is not uniform in space and changes in shape with time. On the contrary, for moving flames experiments showed that the competition between surface