Laminar Flame Propagation Research Articles

Validation of TRF-E as gasoline surrogate through an experimental laminar burning speed investigation

Nowadays, one of the main challenge in the automotive sector concerns the increase of Internal Combustion Engine efficiency. Present and future stringent standards call for reduction of fuel consumption and cut of pollutant emissions. In this respect, one technical solution is the downsizing of the engines that consists in increasing the intake pressure and temperature, through a turbocharger, while reducing the displacement. To avoid abnormal combustion occurrences, the use of high dilution rates is required. It is evident that due to these drastic constraints, high pressure and high dilution, the propagation and the stability of the premixed turbulent flame are strongly affected. Beyond this case, the laminar flamelet regime concept remains the base for the models used in industrial applications. Therefore, the knowledge of laminar burning speed is still crucial and an open research topic. As this parameter is dependent of fuel, its investigation is fundamental in order to evaluate potential suitable surrogates or/and alternative fuels. The present study aims to validate the TRF-E (a Toluene Reference Fuel blended with 5%vol ethanol) as suitable surrogate of a commercial gasoline and to gather a wide laminar burning velocities database for the TRF-E.For that, the laminar flame propagation inside a spherical stainless steel vessel was observed via a Double-View Schlieren technique. The temperature was set at 373, 423 and 473 K, while pressure and dilution were, respectively, 0.1, 0.2, 0.3 and 0.5 MPa and 0, 10 and 20%, for equivalence ratio range from 0.8 to 1.3. Thanks to this large laminar burning velocity database, it was possible to determine coefficients from the mathematical correlation proposed by Metghalchi and Keck (1982) with high precision by solving a global optimization problem. Reference conditions were fixed at 473 K, 0.1 MPa and 0% of dilution. In this case, the laminar burning velocity difference between TRF-E and gasoline is less than 4%. But the decrease of temperature and the increase of pressure or dilution affect the laminar burning velocity of these two fuels in a different way. Anyway, this gap is limited to 10–15% in the worst cases, confirming that TRF-E may be considered as a suitable surrogate of the investigated gasoline.

Experimental Study and Kinetic Modeling of Laminar Flame Propagation in Premixed Stoichiometric n-butane-air Mixture

The laminar burning velocities and propagation speeds of stoichiometric n-butane-air mixture were obtained for outwardly propagating spherical flames by measurements of pressure rise during the early stage of propagation in a spherical vessel. The experiments were carried out at various initial pressures within 0.3 and 1.2 bar, and various initial temperatures within 298 and 423 K. The experimental laminar burning velocities were compared with those provided by the detailed kinetic modelling based on Warnatz mechanism for combustion of C1-C4 hydrocarbons, using INSFLA package. The baric and thermal coefficients of laminar burning velocities, calculated from their dependence on initial temperature and pressure, were compared with coefficients characteristic for other fuel-air mixtures. The overall activation parameters (reaction order and activation energy) are reported and discussed in comparison with similar data characteristic for alkane-air flames.

High-temperature laminar flame speed measurements in a shock tube

High-temperature methane and propane laminar flame speed measurements were conducted behind reflected shock waves in a shock tube. A high-power Nd:YAG laser was used to spark-ignite the shock-heated gas mixtures and initiate laminar flame propagation. High-speed, OH* endwall imaging was used to record the propagation of the spherically expanding flames in time, and a non-linear stretch correlation was applied and used to determine the unburned, unstretched laminar flame speed. “Low-temperature” (<600 K) flame speed results are presented for stoichiometric methane/air and propane/air mixtures at initial unburned gas conditions of 489–573 K and 391–556 K, respectively, and 1 atm. The low-temperature measurements show close agreement with available literature data and kinetic modeling results, thereby validating the shock-tube laminar flame speed measurement approach. “High-temperature” (>750 K) flame speed results are presented for a propane/21% O2-47% N2-32% He mixture (ϕ = 0.8) at initial unburned gas conditions of 764–832 K, 1 atm. The high-temperature measurements fall between kinetic model predictions, but the kinetic model results show significant disagreement, highlighting the need for high-temperature flame speed validation data of this kind. We believe that these results represent the first laminar flame speed measurements conducted in a shock tube, and that the high-temperature results are the highest-temperature, 1-atm flame speed measurements available in the literature.

Comparative analysis of detailed and reduced kinetic models for CH4 + H2 combustion

Directed relation graph with error propagation (DRGEP) method combined with extensive validation for 0D, 1D and 2D CFD modeling supported by sensitivity and Rate-Of-Production (ROP) analyses are implemented for comparative study of detailed and reduced kinetic mechanisms for CH4 + H2 combustion. To this end, two detailed kinetic mechanisms, namely AramcoMech 2.0 and recently updated Konnov mechanism, were validated using available measurements of ignition delay times and laminar burning velocities for hydrogen, methane and hydrogen + methane fuel mixtures. For all experimental conditions visited, both detailed mechanisms demonstrated good and close to each other performance. Two-stage DRGEP method and reaction reduction based on computational singular perturbation (CSP) were then implemented to achieve two skeletal models: 25 species and 105 reactions for AramcoMech 2.0 and 27 species and 107 reactions for the Konnov model. The conditions for skeletal models generation cover ɸ = 0.5–2.0, temperature 900–2000 K, and pressure 1–50 bar. Turbulent non-premixed flames of CH4 + H2 in the Jet in Hot Co-flow (JHC) burner for two different oxygen concentrations in a co-flow were modeled using both skeletal models. 2-D RANS simulations with OpenFOAM code of the flame structure using the two skeletal kinetic mechanisms are similar except for the mass fraction of OH and CO. To elucidate the differences between two skeletal mechanisms generated using the same reduction method, extensive validation for 0D, 1D and 2D CFD modeling were supported by sensitivity analysis for detailed and skeletal reaction models. Good agreement between the skeletal and detailed mechanisms was found in top reactions as well as their sensitivity coefficients, which affect auto-ignition process and laminar flame propagation. Further chemical and sensitivity analysis of the structure of laminar flames demonstrate that three important reactions, i.e. CO + OH = CO2 + H, H2 + OH = H + H2O, and CH4 + OH = CH3 + H2O have different rate constants in the Aramco and Konnov models that may contribute to the differences in the prediction of CO concentration profiles. The simulation predictions for CO concentrations are improved for laminar flames and JHC flame by using a 25-species modified version in which these rate constants were taken from the Konnov mechanism. It was noted that DRGEP method applied to different detailed kinetic schemes generate skeletal models with different, non-overlapping lists of retained species. The presence of CH2CHO in the Aramco 25-species skeletal mechanism and its absence in the Konnov 27-species mechanism, and the presence of CH, CH2, CH2CO in the latter and their absence in the former mechanism were analysed and explained using Rate-Of-Production analysis for conditions found in the CFD simulations.

Ignition of premixed air/fuel mixtures by microwave streamer discharge

A variety of methods exists for fast and efficient combustion of air-fuel mixtures. In this study, a microwave subcritical streamer discharge is used to ignite propane-air mixtures at atmospheric pressure. The streamer is initiated at the inner surface of a dielectric tube with the help of a passive half-wave vibrator. By creating a network of ignition lines, the streamer discharge forms the network of burning channels with large total surface area. This leads to the apparent speed of combustion propagation along the cylinder in excess of 100 m/s, which is more than 200 times the laminar flame propagation speed. The axial propagation of the combustion front in a cylindrical tube filled with the air/propane mixture is investigated by high speed video recording in visible light. A simple model is presented to explain observed results.

Investigation on 1-heptene/air laminar flame propagation under elevated pressures

The laminar flame propagation of 1-heptene/air mixtures covering equivalence ratios from 0.7 to 1.5 is investigated in a constant-volume cylindrical combustion vessel at 373 K and elevated pressures (1, 2, 5, and 10 atm). Laminar flame speed and Markstein length are derived from the recorded schlieren images. A kinetic model of 1-heptene combustion is developed based on our previous kinetic model of 1-hexene. The model is validated against the laminar flame speed data measured in this work and the ignition delay time data in literature. Modeling analyses, such as sensitivity analysis and rate of production analysis, are performed to help understand the high temperature chemistry of 1-heptene under various pressures and its influence on the laminar flame propagation. Furthermore, the laminar flame propagation of 1-heptene/air mixtures is compared with that of n-heptane/air mixtures reported in our previous work. The laminar flame speed values of 1-heptene/air mixtures are observed to be faster than those of n-heptane/air mixtures under most conditions due to the enhanced exothermicity and reactivity.

Microwave-Assisted Flame With Sodium Seeding

Analysis of the laminar flame propagation in the methane–air mixture seeded by sodium with microwave energy coupling to the flame front was presented. Calculation results showed that a flame suppression effect caused by sodium could be reduced by the microwave discharge, but an increase in the sodium concentration up to 0.5% leads to overheating of combustion products and flame extinguishment. Thermal effect of the microwave discharge influence on the laminar flame speed prevails, but additional slight increase in a flame speed is caused by the formation of excited oxygen species.

Numerical Simulation of Propagation of Unsteady Tribrachial Flames in Laminar Non-Premixed Jets

The characteristics of propagating Tribrachial Flames in non-premixed laminar jets have been investigated computationally, using a two dimensional model in ANSYS FLUENT 16.0. The edge of the propagating flame in a laminar jet regime has a Tribrachial flame structure: a lean premixed flame, a rich premixed flame, and a diffusion flame, all extending from a single location. This is usually observed in non-premixed combustion such occurring in burners. Such flames are important in the interaction of heat and mass transfer with chemical reactions in gas turbines and commercial burners. A computational study has been performed to assess the laminar tribrachial flame propagation in methane jets and to compare the tribrachial flame propagation for various flow rates. With an increase in the fuel jet Reynolds number, the tribrachial point is found to move closer to the nozzle. Additionally the tribrachial point is found to become larger with an increase in the Reynolds number.

Mechanism Reduction and Bunsen Burner Flame Verification of Methane

Based on directed relation graph with error propagation methods, 39 species and 231 reactions skeletal mechanism were obtained from Mech_56.54 (113 species and 710 reactions) mechanism of methane. The ignition delay times, laminar flame propagation speed, and important species were calculated using the simplified mechanism at different pressures and equivalence ratios. The simulation results were in good agreement with that of detailed mechanisms and experimental data. The numerical simulation of the Bunsen burner jet flame was carried out using the simplified methane mechanism, and the simulation results well reproduced the temperature, flow fields and distribution of important species at flame zone. The compact methane reduced mechanism can not only correctly respond to its dynamic characteristics, but also can be well used for numerical simulation, which is of great significance in engineering applications.

Characterization of flame front propagation during early and late combustion for methane-hydrogen fueling of an optically accessible SI engine

In recent years, hybrid and fully electric vehicles have received significant consideration since they represent an alternative sustainable transport to the conventional fossil-fuel powered vehicles. However, a worldwide implementation of this alternative propulsion can induce large and undesirable peak demands in distributed power systems. In this context, natural gas spark ignition engines are a promising form of technology to supply part of the energy demand. The main limitations related to low laminar flame propagation speed and poor lean-burn capabilities of natural gas can be overcome by using hydrogen as additional fuel. In this paper, a comparison was carried out between methane and different CH4/H2 mixtures. Specifically, low levels of hydrogen addition were used (5%, 10%, 20% volumetric basis) in stoichiometric and lean burn conditions. The measurements were carried out in an optically accessible single-cylinder port fuel injection spark ignition engine. Optical measurements were performed to analyze the combustion process with high spatial and temporal resolution. In particular, optical techniques based on 2D-digital imaging with two different combustion chamber views were used. Macroscopic (global) and microscopic (local) post-processing tools were implemented to provide a detailed analysis of the flame front propagation process. Moreover, an in-depth analysis was performed to study the flame penetration in the piston top-land crevice. Exhaust gas emissions were also characterized and linked with thermodynamic and optical data. In order to evaluate the combustion process in similar fluid-dynamic conditions, all measurements were performed under steady-state conditions at fixed engine speed, load and spark advance. All the results highlight fast combustion promotion due to the hydrogen addition. In addition, hydrogen reduces the preferential propagation of the flame in a certain direction and increases the flame front wrinkling. Flame propagation in the top-land crevice region was measured for methane and its blends with hydrogen, which represents an original contribution to the literature. An inverse trend was seen between flame penetration in the crevice and unburned hydrocarbon emissions. Lastly, tests in lean conditions demonstrate the potential to decrease nitrogen oxides emissions when methane and methane-hydrogen blends are used.

Experimental investigation of gliding arc plasma fuel injector for ignition and extinction performance improvement

Flame extinction at high-altitude is one of the serious safety problems for aero-engines. The low pressure and temperature at high-altitude make it difficult to relight after extinction. Plasma-assisted combustion has been widely investigated in aerospace propulsion systems, while the mechanism is still not clear. In this study, a novel gliding arc plasma fuel injector using alternating current discharge is proposed to obtain reliable altitude relight performance and wider lean blow-out limits. The ignition and extinction experiments of gliding arc plasma fuel injector using 5 °C and −30 °C kerosene (RP-3) were conducted. A thin and string-like gliding arc plasma column was observed with repeating phases of breakdown between the fuel atomizer and venturi nozzle, extension with rotating airflow and column quenching. The optical emission spectroscopy of gliding arc plasma in gliding arc plasma fuel injector indicated the significant thermal effect caused by the arc column. Using gliding arc plasma fuel injector, the ignition limit was greatly extended, almost to the lean blow-out limits for the low temperature fuel. Low temperature and low injection pressure lead to much larger droplets and irregular injection cone. Influenced by heating and hydrodynamic effect of gliding arc plasma, the drop size at −30 °C kerosene spray decreases from around 150 μm to 30 μm, which is a main reason for ignition range extension. The equivalence ratios of lean blow-out were extended by up to 48% and 47% using 5 °C and −30 °C kerosene, respectively. Several light hydrocarbons, such as CH4 (1.26 SLM), C2H4 (1.31 SLM) and C2H2 (2.30 SLM) with larger laminar flame propagation velocity, were detected as reforming products. Both heating and reforming effects contribute to the lean blow-out limit extension. The residence time of kerosene sprays in gliding arc plasma fuel injector is the determining factor for conversion capability.

Numerical Study on the Propagation of Premixed Flames in Confined Narrow Disc-Shape Chambers

ABSTRACTThe laminar flame propagation in narrow confined disc-shape chambers of millimeter scale is investigated, concerning the flame front displacement speed and the influences from the changes of the gap width and radius. An asymptotic analysis treating the flame front as a discontinuity successfully predicts the velocity profiles of the flame front and illustrates the importance of heat release parameter and laminar flame speed of the fuel. The unsteady flame propagation process is simulated by a full numerical computation which employs the n-butane/air mixture as the reactant. The numerical simulation emphasizes the sensitivity of spatial scale to the flame propagation in narrow spaces, indicating that the acceleration rate and the maximum speed of the flame have a non-monotonic relation with the gap width, of which the optimal value is about 0.8 mm. Faster flame propagation is favored for larger gap radius due to stronger flame straining, but it is restricted by the gap width.

Experimental study of effect of hydrogen addition on combustion of low caloric value gas fuels

The effect of hydrogen on the premixed combustion of low calorific value gas in cylinder was carried out. The engine bench test system was built, and the effects of hydrogen on the pressure in cylinder, the characterization parameters of flame stability, flame shape, combustion cycle variation, flame surface structure and development were studied. The experimental results show that adding hydrogen to low calorific value gas fuels can increase laminar flame propagation rate, increase heat release rate, improve engine volumetric efficiency and reduce engine cycle variation. With the increase of hydrogen fraction, the maximum cylinder pressure of the engine rises, the corresponding crankshaft angle moves forward, and the flame development period and the rapid combustion period of the engine working cycle are reduced. The flame propagation rate of hydrogen blended low calorific value gas is larger, which enhances the strength of the vortex blob in cylinder to some extent. The increase of hydrogen fraction in mixture increases the flame propagation velocity, and enhances the effect of the combustion process on vortex intensity in cylinder, which increasing the effect of vortex blob on the flame surface structure. With the increase of hydrogen fraction, the vortices of the flow field in the cylinder increase, the time of which the flame surface reaches the same fold is in advance, and the flame development period is shortened.

Rate-controlled constrained equilibrium for large hydrocarbon fuels with NTC

The rate-controlled constrained equilibrium (RCCE) method is a thermodynamic-based dimension reduction method that enables the representation of a reactive system involving chemical species in terms of a smaller number, , of constraints and thus reduces the computational burden imposed by detailed chemical kinetics. The application of RCCE for large hydrocarbon fuels like n-heptane has rarely been reported due to the challenges in the specification of constraints. In this study, a systematic approach of constraint specifications for hydrocarbon fuels with negative temperature coefficients behaviour has been proposed. Specifically, the bimolecular species lumping consistent with partial equilibrium assumption (PEA) makes the thermodynamics-based constrained equilibrium manifolds a good approximation to the actual kinetics-controlled slow invariant manifolds in reactive systems. Sensitivity-aided optimisation for species constraints has been formulated to improve the prediction of two-stage ignition. Two sets of optimised constraints for high- and low-temperature ignitions e.g., High-T C and Low-T C with 47 and 48 constraints have been developed from an 88-species n-heptane skeletal mechanism. The method has been successfully demonstrated in the two-stage auto-ignition of n-heptane/air mixture over a wide range of pressures and temperatures. The results show that the dynamics predicted with RCCE agree well with that from the full description. The one-dimensional laminar flame propagation simulation demonstrates that the constraints from auto-ignition can be applied for flame simulations and the RCCE reduced description of flame is less sensitive to the selection of constraints. Moreover, a more compact RCCE description with only 16 species constraints is capable of accurate prediction of the flame propagation process.

Model of the low-temperature heat release and ignition of n-butanol

The low-temperature ignition of n-butanol and air mixtures is studied in this work. A short chemistry model of 14 reactions, for this low-temperature phenomenon, was obtained from a reduced chemical mechanism of 279 reactions with 62 chemical species that reproduces a wide range of combustion experiments: ignition delay times, jet-stirred reactor measurements and laminar flame propagation. Both chemical mechanisms include low-temperature chemistry to more accurately model ignition times for temperature ranges below 1000 K. Since there is no conclusive experimental evidence about the existence of NTC (negative temperature coefficient) behaviour for n-butanol, the present work addresses a theoretical–numerical analysis showing that this alcohol, does not present an NTC behaviour. It was found that the low-temperature kinetics is able to increase only slightly the temperature in a relatively short time. Additionally, the reaction involving CHO and OH represents the chain termination reaction in the low-temperature regime (T<1000 K) that prevents an NTC behaviour of n-butanol. The final ignition event then requires the chain branching mechanism via HO-HO-2OH to be activated, which is very slow at low temperatures. Analytical results show the parametric influence of the resulting two-stage ignition process of n-butanol at low temperatures.

Optimized single-step (OSS) chemistry models for the simulation of turbulent premixed flame propagation

A simple and efficient triple-optimization procedure (TOP) is introduced to determine single-step chemistry model parameters. The cornerstone of the proposed approach lies in the introduction of a fictive (or virtual) chemical species, the physical characteristics of which are set to recover some essential properties of combustion and flames. Special emphasis is presently placed on the capability of such a global kinetic scheme to recover three parameters that are recognized as the most influential in terms of turbulence–chemistry interactions and turbulent premixed combustion regimes. These parameters are (i) the burnt gases temperature Tb, which settles the value of the thermal expansion factor τ=(Tb−Tu)/Tu, (ii) the propagation velocity SL0, which is mandatory to reproduce the flame dynamics, and (iii) the laminar premixed flame thickness δL0. In practice, the thermochemical properties of the fictive species (hereafter denoted by AΦ) are set to account for the impact of dissociation effects and partial oxidation of the fuel, i.e., presence of species other than H2O and CO2 in the burnt gases, which allows to recover a satisfactory estimate of Tb. The value of the pre-exponential factor associated to the single-step Arrhenius law is also optimized to reproduce the laminar flame propagation velocity. Finally, the transport characteristics are determined to recover a satisfactory estimate of the thermal flame thickness. The method is general in its principles and quite easy to implement. It is applicable to any couple of fuel and oxidizer. Attention is focused on the application of the method to any stoichiometry but it is also shown that the influence of both pressure and fresh reactants temperature can be recovered. The performance of the resulting optimized single step (OSS) chemistry models are assessed through a direct comparison with detailed chemistry results. Computations of one-dimensional laminar flames are performed with the OSS model using the Cantera software for a wide range of pressure levels, fresh reactant temperatures, and equivalence ratios. Obtained results do show that the flame propagation velocity is correctly reproduced for the whole range of parameters, with a maximum value recovered in the vicinity of stoichiometry, a decrease towards rich conditions, and a satisfactory pressure dependence. Burnt gases temperature as well as thermal flame thickness values are also in excellent agreement with those issued from the reference detailed kinetics models. The OSS model is then used to perform direct numerical simulation (DNS) computations of flame kernel growths in both laminar and turbulent conditions. The comparison of obtained OSS results with detailed chemistry computations further confirms the relevance and performance of the proposed methodology.

Recent Trends in the Production, Combustion and Modeling of Furan-Based Fuels

There is growing interest in the use of furans, a class of alternative fuels derived from biomass, as transportation fuels. This paper reviews recent progress in the characterization of its combustion properties. It reviews their production processes, theoretical kinetic explorations and fundamental combustion properties. The theoretical efforts are focused on the mechanistic pathways for furan decomposition and oxidation, as well as the development of detailed chemical kinetic models. The experiments reviewed are mostly concerned with the temporal evolutions of homogeneous reactors and the propagation of laminar flames. The main thrust in homogeneous reactors is to determine global chemical time scales such as ignition delay times. Some studies have adopted a comparative approach to bring out reactivity differences. Chemical kinetic models with varying degrees of predictive success have been established. Experiments have revealed the relative behavior of their combustion. The growing body of literature in this area of combustion chemistry of alternative fuels shows a great potential for these fuels in terms of sustainable production and engine performance. However, these studies raise further questions regarding the chemical interactions of furans with other hydrocarbons. There are also open questions about the toxicity of the byproducts of combustion.

Investigation on laminar flame propagation of n-butanol/air and n-butanol/O2/He mixtures at pressures up to 20 atm

Bio-butanol is an important alternative fuel and has many advantages in engine combustion. In the present work, laminar flame propagation of n-butanol/air and n-butanol/(14% O2/86% He) mixtures was investigated using a constant-volume combustion vessel at the unburnt temperature of 423 K, initial pressures of 1–20 atm and a series of equivalence ratios. Flame instabilities of n-butanol, including cellular instability and pulsating instability, were studied based on flame morphology. The unsteady transition from weak flame to normal flame was investigated based on the flame trajectories and this phenomenon became less perceptible in the flame with stronger combustion intensity and smaller Lewis number. The accelerated laminar burning velocity (LBV), thickened flame thickness, larger Markstein length and Markstein number indicate that the thermal diffusivity of n-butanol/O2/He flames are greatly enhanced by helium addition. The smaller densities and lower reactant concentrations result in the smaller laminar burning fluxes of n-butanol/O2/He flames than those of n-butanol/air flames. The high temperature kinetic model of n-butanol reported by Cai et al. was further developed with recent theoretical progresses on n-butanol reactions. The updated high temperature model was validated on the present experimental data and a vast amount of previous n-butanol combustion data. Sensitivity analysis was performed using the updated model under wide pressure and equivalence ratio ranges. The similarity in the sensitivities indicates that the sensitive reactions in n-butanol/air flames can be validated by using n-butanol/O2/He flames, which greatly compensates the problem that the n-butanol/air flames are susceptible to flame instabilities at high pressures. The weaker pressure dependence of the LBVs of n-butanol/O2/He flames indicates that their flame chemistry changes less to resist the pressure variation.

Influence of water mist on propagation and suppression of laminar premixed flame

The combustion of premixed gas mixtures containing micro droplets of water was studied using one-dimensional approximation. The dependencies of the burning velocity and flammability limits on the initial conditions and on the properties of liquid droplets were analyzed. Effects of droplet size and concentration of added liquid were studied. It was demonstrated that the droplets with smaller diameters are more effective in reducing the flame velocity. For droplets vaporizing in the reaction zone, the burning velocity is independent of droplet size, and it depends only on the concentration of added liquid. With further increase of the droplet diameter the droplets are passing through the reaction zone with completion of vaporization in the combustion products. It was demonstrated that for droplets above a certain size there are two stable stationary modes of flame propagation with transition of hysteresis type. The critical conditions of the transition are due to the appearance of the temperature maximum at the flame front and the temperature gradient with heat losses from the reaction zone to the products, as a result of droplet vaporization passing through the reaction zone. The critical conditions are similar to the critical conditions of the classical flammability limits of flame with the thermal mechanism of flame propagation. The maximum decrease in the burning velocity and decrease in the combustion temperature at the critical turning point corresponds to predictions of the classical theories of flammability limits of Zel'dovich and Spalding. The stability analysis of stationary modes of flame propagation in the presence of water mist showed the lack of oscillatory processes in the frames of the assumed model.

Determination of global kinetic parameters by optimization procedure using burning velocity measurements

The optimization procedure was developed to derive the global kinetic parameters using experimental dependence of burning velocity on the equivalence ratio. The simple model of laminar premixed flame propagation with assumed constant parameters was used to demonstrate the features of the suggested procedure. The suggested method allows finding optimal parameters for the defined functional dependence of the reaction rate on the temperature and reactant concentrations. The dependence of combustion adiabatic temperature on equivalence ratio is assumed to be known from the flame equilibrium calculations. The global kinetic parameters of combustion reaction were determined for methane, ethylene and propane mixtures with air on the basis of experimental data on burning velocity as function of the equivalence ratio. The calculated overall kinetic parameters are compared with parameters obtained by other methods within similar global model.