Laminar Flame Velocity Research Articles

Simulation study on combustion reaction mechanism and heat release rate of ammonia/methane fuels

ABSTRACT Ammonia/methane combustion has the potential to be a viable method for achieving low-carbon combustion. However, further research is required to enhance the combustion mechanism and to gain a deeper understanding of the heat release rate associated with ammonia/methane combustion. A one-dimensional simulation of premixed laminar ammonia/methane flame simulation was carried out based on Okafor ammonia/methane reaction mechanism. The mole fraction of radicals and heat release rate in the ammonia/methane combustion process under different conditions were calculated using CHEMKIN-PRO. The results show that the optimized reaction mechanism was in line with the experimental results in predicting the laminar flame velocity in the fuel-lean zone. The distances between the peak values of NH and heat release rates were small at XNH3 = 0.1 ~ 0.6 and fuel-rich condition. The correlation between NH and the heat release rate was significant, indicating that NH radicals are suitable as markers of the heat release rate in the ammonia/methane flames. The abilities for characterizing heat release rate of [CH][OH], [CH][NO], [NH][OH], [NH][NO], [NH2][OH], and [NH2][NO] were further evaluated. The exponent was added to the radical combination to improve the correlation with heat release rate. [NH]0.88[OH]0.01, [NH]0.92[NO]0.25, [NH2]0.92[OH]0.42, and [NH2]0.97[NO]1.27 correlate well with heat release rates from ammonia/methane flames and they can be used as good markers of heat release rates.

The combustion mechanism of aluminium in the steam/carbon dioxide mixed atmosphere

AbstractThe ignition and combustion characteristics of aluminium (Al) in the steam/carbon dioxide (H2O/CO2) mixed atmosphere were calculated by using a close homogeneous catch reactor and premixed laminar flame‐speed of CHEMKIN‐PRO. The effects of initial reaction temperature and H2O/CO2 ratios on the system temperature, products, and ignition delay time were explored. The main reaction paths were analyzed by the temperature sensitivity. Al (l) entered the system with a pronounced phase transition and only one heating stage, but there are two heating stages in the Al (g) system. The reaction of Al in the H2O/CO2 mixed atmosphere has a positive effect on the ignition delay time of the system. The high contents of CO2 in the H2O/CO2 mixed atmosphere can increase the maximum temperature of system and decrease the ignition delay time. Temperature sensitivity analysis shows that AlO, Al2O, and AlOH are important intermediate products, and Al2O2 is the main substance that produces Al2O3. The dominant reaction path is Al → AlOH→AlO → Al2O → Al2O2 → Al2O3. In addition, when the initial temperature was 2300 K, the laminar flame velocity was calculated to reach 35.6 m/s.

Study on the flame structure and flow field of hydrogen-enriched combustion in array micro-tube

Addressing climate change and reducing greenhouse gas emissions are critical priorities. Utilizing hydrogen-rich methane or pure hydrogen as fuels within gas turbines, facilitated by array micro-tube premixed combustion technology, is anticipated to markedly accelerate the decarbonization process of the energy sector. In this study, the flame structure of the array micro-tube premixed burner under various fuel compositions was examined using OH-Planar Laser-Induced Fluorescence and Particle Image Velocimetry measurement techniques. The effects of the equivalence ratio (φ) and the hydrogen power ratio (HPR) on the characteristics of the flame front, including its curvature, density, volume, and the associated flow field properties, were discussed. As φ and HPR increase, the wrinkled structure of the flame front is significantly enhanced, with a more pronounced effect on smaller scales. This enhancement leads to the separation of the unburned pockets from the main flame. Concurrently, both the flame length and the flame area decrease with the augmentation of φ and HPR, indicating a more concentrated combustion process and increased combustion intensity under hydrogen-enriched and pure hydrogen conditions. The study also observed a slight increase in both the negative and positive curvatures of the flame front, with a more notable increase in the negative curvature. The increased negative curvature results in an elevated degree of wrinkling and a higher value of Σ (flame surface density), reaching a maximum of 0.876 mm−1 under the conditions where φ is 0.8 and ⟨c⟩ (mean progress variable) is 0.5, resulting in the smallest observed flame volume of 100.6 mm3. Upon coupling the flame with the flow field, it was discovered that the exit flow field of the array micro-tube exhibits symmetry and a characteristic conical flame shape. The burning velocity of the side flame brushes increases, and the velocity peak shifts upstream. The aforementioned findings confirm that the addition of hydrogen increases the laminar flame velocity, enabling the flame to stably anchor to the microtube outlet and thereby enhance the flame's robustness and stability.

Numerical Study on the Potential of Stratified Mixture to Improve Thermal Efficiency and Reduce Carbon Emissions in High-Speed Gasoline Direct Injection Engine

Abstract Stratified combustion improves the indicated thermal efficiency (ITE) of gasoline direct injection (GDI) engines, but the mechanism of its impact on unregulated emissions remains unclear. In this simulation-based study, double injection strategies were used to create stratified mixtures in the cylinder. The results indicated that as the second fuel injection quantity (FIQ) was increased or as the second fuel injection timing (FIT) was delayed, the oil-film mass increased, leading to an increase in soot emissions. The formation of a large area of stoichiometry (STO) region at the spark plug and at its right side increases the laminar flame velocity and improves the ITE. At 4000 rpm, the ITE of case2-2 (with a second FIT of −220 °CA after top dead center (ATDC) and a second FIQ of 65.5 mg) increased by 1.6% compared to the original scheme. With the increase in STO area, NOx emissions and the content of CH3OH and CH2O increased, while carbon monoxide (CO) and greenhouse gas emissions showed a decreasing trend. Compared to the original scheme, CO and greenhouse gas emissions decreased by 1.97% and 6.7%, respectively, in case2-2. This study provides guidance for the development of GDI engines with high ITE and low carbon emissions.

Revisit the benzene oxidation at elevated pressure

The benzene (A1) oxidation was examined in a jet-stirred reactor (JSR) within the temperature range of 880–1010 K at 12.0 atm under both fuel lean (Φ = 0.5) and rich (Φ = 3.0) conditions. Eighteen intermediates and products were identified and quantified by gas chromatography (GC) and gas chromatograph-mass spectrometer (GC–MS). A kinetic model comprising 280 species and 1734 reactions was developed and validated against the experimental data to investigate the benzene reactions occurring at high pressure and low temperature. According to the sensitivity analysis, A1 + OH = A1- + H2O is the most promoting reaction for fuel consumption, while A1OH + O2 = A1O + HO2 and A1OH + OH = A1O + H2O exhibited the most inhibiting effects. HO2 radicals play an important role in the initial reaction temperature of A1 high-pressure oxidation, where the reaction rate of A1OH + O2 = A1O + HO2 is particularly critical. In comparison to previous works on A1 oxidation, oxygenated polycyclic aromatic hydrocarbons (OPAHs) benzofuran (C8H6O) and dibenzofuran (C12H8O) were newly measured and analyzed in this work. As one of the most important OPAHs species, the consumption pathway of C8H6O was updated to better describe the high-pressure oxidation. The C8H6O would potentially compete with A1 for molecular oxygen via the pathway A1 → A1O → C8H6O → decomposition products, and the process of decomposition enhances the oxygen depletion. Compared with previous oxidation studies at atmospheric pressure, the A1 initial reaction temperature shifted from 1000 to 950 K, and the temperature window of fuel conversion sharply reduced from 300 K to 70 K. Additionally, the model was effectively applied to predict the oxidation of A1 in a Jet-Stirred Reactor (JSR) over a wide range of pressures, from 0.46 to 12.0 atm. Furthermore, the developed model was compared with the laminar flame velocities (LBVs, ranging from 1.0 - 10.0 atm) and the ignition delay times (IDTs, ranging from 2.4 – 9.0 atm) data in the literature, and satisfactory agreement was obtained across a broad pressure range. The newly reported data and kinetic model provide helpful in further understanding the combustion mechanisms of aromatic hydrocarbon fuels.

Experimental Estimation of Turbulent Flame Velocity in Gasoline Vapor Explosion in Multi-Branch Pipes

The overpressure characteristics of gasoline explosions in multi-branch pipes are caused by various factors, with flame velocity as a particularly significant determinant. Overlooking the impact of turbulent flow in the branch pipes can induce a significant discrepancy in the outcome when using laminar flame velocity to determine the maximum rate of overpressure rise. To quantify the impact of turbulent flame velocity on the rate of overpressure rise in the gasoline explosions within branch pipes, the laminar flame velocity was replaced with its turbulent counterpart. Additionally, modifications to the formula for calculating the maximum overpressure rise rate were implemented. Then, experimental data of peak explosion overpressure and overpressure rise rate under different numbers of branches were obtained. Finally, the empirical data were inputted into the modified formula to determine the maximum rate of overpressure rise, thus enabling the calculation of the turbulent flame velocity across varying numbers of branches. The findings reveal a positive correlation between the number of branches and the turbulent flame velocity during tube explosions. When the number of branch pipes increased from 0 to 4, the turbulent flame velocity was found to range from 8.29 to 13.39 m/s. The increase in the number of branches did not consistently enhance the turbulent flame velocity. As the number of branches increased from zero to three, the turbulent flame velocity rose accordingly. Differently, as the number of branches exceeds three, the turbulent flame velocity exhibits fluctuations and peaks at a level approximately 1.8 times higher. The research method of this paper can provide a reference for estimating the turbulent flame velocity in the combustion process of flammable gas explosions in multi-branch tunnels.

Combustion mechanism study of ammonia/n-dodecane/n-heptane/EHN blended fuel

Due to the challenges of ammonia, such as high ignition energy and slow flame propagation speed, the utilization of ammonia in engines might necessitate the implementation of dual-fuel combustion modes along with the use of cetane improvers. To optimize the performance of ammonia-fueled engines, and achieve efficient and clean combustion, three-dimensional computational fluid dynamics (CFD) simulations are imperative. However, prior to conducting a three-dimensional CFD study, an accurate reaction mechanism for each component is essential. In this study, the blending mechanisms of ammonia, n-dodecane, and 2-ethylhexyl nitrate (EHN) were constructed using CHEMKIN software, including 243 species and 1293 reactions. The calculated results of ignition delay, laminar flame velocity, and the concentration of significant species agreed well with experiment results. The ignition delay, laminar flame velocity, adiabatic flame temperature, and the concentration of major products were analyzed in different blending ratios. The use of high cetane fuel shortens ignition delay and increases laminar flame speed. As the equivalence ratio of ammonia increases, the concentration of NO decreases while the concentration of H2 increases. The combustion process is also analyzed based on optical diagnostic results, and the impact of the ammonia/n-dodecane mixtures blended with EHN on the combustion process is investigated. The addition of EHN proved to shorten the ignition delay of the mixture. Furthermore, the introduction of EHN exhibits marginal influence on NOx generation, with the predominant augmentation of NOx emissions stemming from fuel-derived NOx resulting from the fuel's inherent nitrogen content. Due to the small amount of EHN added, the overall impact is relatively small.

Investigation of the multicomponent syngas composition and CO2/N2 dilution on the adiabatic flame velocity and overall activation energy

Biomass gasification can result in different syngas compositions with distinct laminar flame velocities. These velocity variations must be evaluated and measured to allow the design of appropriate combustion systems. Thus, the objective of this work is to evaluate the effect of the multicomponent syngas composition and the CO2/N2 dilution on the adiabatic flame velocity and overall activation energy. The experimental results are compared with values obtained through chemical kinetics mechanisms San Diego (2016), HP-Mech (2017), FFCM-1 (2016) and Goswami (2014). It is observed that reducing the H2/CO ratio from 1.00 to 0.43 results in a 16 % reduction in the adiabatic flame velocity, while the activation energy increases by 21 %. A correlation for adiabatic flame velocity as a function of dilution mass fraction is also developed. The chemical kinetics analysis allowed the evaluation of the main reactions responsible for the increase in flame velocity due to the addition of H2.

Effect of Impurities on Lean Laminar Hydrogen–air Flames

Simulations of the effect of addition of H, O, OH, HO2, and H2O2 on the structure and propagationof laminar flames in lean (12 and 15%) hydrogen-air flames are performed at pressures of 1 and 6 bar. Itis found that impurities in concentrations of no more than 0.1% do not have any significant effect on laminarburning velocity. When initial temperature is increased to 400 K, the effect of impurities becomes evenweaker. Among the impurities under study, only the addition of OH reduces the laminar flame velocity. Theweak effect of the impurities is attributed to fast formation of intermediate products via reactions involving Oand H atoms without noticeable change in heat release rate. An increase in initial pressure to 6 bar does notchange the effect of impurities.

One-dimensional mechanism of gaseous deflagration-to-detonation transition

A one-dimensional mechanism of deflagration to detonation transition is identified and investigated by an asymptotic analysis in the double limit of large activation energy and small Mach number of the laminar flame velocity. The unsteady analysis concerns the self-accelerating tip of an elongated flame in a smooth walled tube. The flame on the tip, considered as plane and orthogonal to the tube axis, is pushed from behind by the longitudinal flow resulting from the cumulative effect of the radial flows of burned gas issued from the lateral flame of the finger-like front (called backflow in the following). The analysis of the one-dimensional dynamics is performed by coupling the flame structure with the downstream-running compression waves propagating in the external flows. A critical elongation is identified from which the slightest increase in elongation leads to a pressure runaway producing the flame blow-off. The dynamics of the inner structure of the laminar flame on the tip which is accelerated by the self-induced backflow is characterized by a finite-time singularity of the reacting flow in the form of a dynamical saddle-node bifurcation.

Multi-fidelity neural network for uncertainty quantification of chemical reaction models

Surrogate models are often used to accelerate the uncertainty quantification (UQ) of chemical kinetic models. However, the construction of surrogate models usually requires the repetitive generation of high-fidelity input-output samples, which is time-consuming. In this work, we utilize a multi-fidelity neural network to speed up the surrogate model construction, yielding a multi-fidelity neural network-based surrogate model (MFNNSM). MFNNSM consists of two separate neural networks. The first neural network learns from high and low-fidelity samples, and then generates samples to train the second neural network for the subsequent UQ analysis. Based on the fact that the uncertainty similarity (sensitivity-based similarity) does exist between the predictions from the reduced and detailed combustion kinetics models, or between the predictions under different conditions, MFNNSM can use reduced model predictions as low-fidelity samples to generate detailed model predictions as the high-fidelity samples, or can transfer samples across different simulations conditions. To demonstrate the MFNNSM method, the ignition delay time (IDT) and laminar flame velocity (LFV) of methanol and n-decane are chosen as model prediction targets for UQ analysis. The results show that MFNNSM can achieve acceleration factors up to 6, by utilizing reduced model samples to generate detailed model samples under the same conditions, and when reusing the reduced model samples under different conditions, the acceleration factor can increase to 10. In addition, the influences of the relative error of the reduced models and the uncertainty similarity coefficients between combustion conditions on the performance of MFNNSM are further discussed, providing the guidance for future applications of MFNNSM.

Examination of combustion behaviors and emissions of hydrogen enriched propane/methane fuel under external acoustic application

In this study, the instability and emission changes of hydrogen-enriched methane-propane fuel under external acoustic application in a premixed and vortex assisted system were investigated. In the experiment, 67% -33% and 63,5% -31,5% -5% were studied under different acoustic stresses as fuel mixtures. It is known that hydrogen can reduce the emission parameters polluting the environment and its effect on combustion stability. For this reason, interest in the use of hydrogen fuel with other fuels has increased. It may be possible to improve the combustive performance properties of compatible methane and propane mixtures by adding hydrogen. Also, the effects of acoustic applications were examined. Addition of hydrogen to the methane/propane flame increased the heating value of the mixture and caused flame instability due to the increase in laminar flame velocity. There was an increase of 12.2% in light intensity. When the amount of hydrogen increased, the flame was more resistant to acoustic stress. High dynamic pressure fluctuations occurred with 90 Hz acoustic forcing. The emission capacity of the mixture to which hydrogen is added by acoustic forcing has consistently higher values. This was attributed to the change in reaction kinetics due to the increased content.

Turbulence influence factor estimation of gasoline-air explosion in multi-branch tubes

To estimate the turbulence influence of the branch tubes on the rising rate of gasoline-air mixture explosion overpressure, turbulence factor α was introduced to modify the formula of the peak rise rate of explosion overpressure. Then, the experimental data of peak explosion overpressure and overpressure rise rate under the different numbers of branches were obtained. Finally, the experimental data and laminar flame velocity were put into the overpressure rise rate correction formula, and the turbulence influence factors under different branches were calculated. The results show that increasing the number of branches will improve the turbulence degree of the explosion process. When the number of branching pipes is 1, the turbulence impact factor is about 2.0 times that in the case of no branch tube, while when the number of branch tubes is more than 1, the turbulence impact factor fluctuates about 3.5 times.

Experimental study of the ignition chamber with accelerating cavity applying to methanol lean combustion

Owing to the high laminar flame velocity and broad flammability limit of methanol (CH3OH), it is ideal for lean burning. How to obtain high energy and reliable ignition is one of the biggest challenges with lean or ultra-low combustion. To gain good ultra-lean burn performance, one solution is utilizing an turbulent jet ignition (TJI)system. Moreover, the methanol can be directly used in the jet ignition chamber for its low vaporization temperature and volatile characteristics. To enhance the methanol jet ignition performance, the two-stage accelerating cavity was applied to accelerate the combustion and extend the lean-burn limit in this research. In a optical experimental apparatus, jet ignition and combustion process of premixed methanol in the main combustion chamber (MCC) were investigated using the shadowgraph and transient pressure data acquisition methods. The experiment results showed that the pressure of the MCC emerged an obvious two-stage rising process to use the two-stage accelerating cavity (SAC). In addition, when the SAC was applied in the ignition chamber (IC), the proportion and peak value of the first stage heat release in the MCC were clearly higher than those of the single straight hole (SSH). Moreover, the ignition chamber compounded with SAC exhibited a short ignition delay and long jet ignition duration. Compared to SSH, the methanol combustion duration in the MCC by using SAC shortened by approximately 28% under both stoichiometric and lean conditions. In other words, The SAC accelerated the combustion process of methanol. More significantly, it was found that the proper secondary acceleration hole diameter (SAHD) play an crucial role in the jet ignition and combustion process, especially under ultra-lean conditions. In addition, by utilizing SAC-3-4.5, the combustion duration of was shortened by 41.9% than that of using SAC-3-3 at the equivalence ratio of 0.6. Finally, the ultra-lean burn limit could be extended to 0.35 by using SAC-3-4.5, which greatly expanded the methanol lean combustion limit.

Numerical Modeling of Hydrogen Combustion: Approaches and Benchmarks

The paper is devoted to the analysis of two different approaches for the numerical simulation of gaseous combustion. The first one is based on a full system of Navier-Stokes equations describing the dynamics of the compressible reactive medium, while the second one utilizes low-Mach number approximation. The compressible model is realized by the traditional low-order numerical scheme and the contemporary CABARET method. The low-Mach approach is implemented on the base of a widely known FDS numerical scheme. The benefits and disadvantages of compressible and low-Mach approaches are discussed and demonstrated on a specially developed set of problem setups, applicable for validation and verification of the numerical methods for combustion analysis. In particular, the laminar flame velocity test, spherical bomb test, and multidimensional modeling of combustion development inside the rectangular closed vessel are performed via both techniques that allowed to determine the applicability limits of the low-Mach number approximation.

Simplification and Verification of O-xylene Fuel Mechanism

The increasing demand for energy due to economic globalization has led to the exploration of different types of fuels, including aromatic hydrocarbon fuels. Xylene is an essential aromatic hydrocarbon fuel and an important component of kerosene. This study employs the error propagation directed relationship diagram (DRGEP) and sensitivity analysis (SA) to simplify the reaction mechanism of o-xylene. The ignition delay time and laminar flame velocity predicted by the fuel mechanism under different w375orking conditions are compared with pre-simplified experimental data. The study proposes a mechanism consisting of 298 reactions and 64 components to describe the combustion reaction of xylene. The simplified mechanism's ability to reproduce experimental results is assessed, and the results reveal that the simplified mechanism effectively reproduces the experimental results, indicating its potential usefulness in practical applications. This study has significant implications for the development of more efficient and sustainable energy sources. By providing insights into the combustion behavior of xylene, researchers can develop more accurate models for predicting the performance of this fuel under a range of conditions. This, in turn, can inform the development of new technologies that can help meet the growing demand for energy in a more sustainable and environmentally friendly way. Overall, this study contributes to our understanding of the combustion behavior of xylene, highlighting its potential as a sustainable energy source and offering a potential avenue for further research in this field.

Study on the Skeleton Mechanism of Second-Generation Biofuels Derived from Platform Molecules

This paper focuses on the combustion mechanism of furan-based fuels synthesized from lignocellulose. The fuel is a binary alternative fuel consisting of 2-methylfuran and 2,5-dimethylfuran derived from furfural. The key reactions affecting the combustion mechanism of this fuel were identified via path analysis, and the initial reaction kinetic mechanism was constructed using a decoupling methodology. Then, a genetic algorithm was used to optimize the initial mechanism. The final skeleton mechanism consisted of 67 species and 228 reactions. By comparing experimental data on ignition delay, component concentration, and laminar flame velocity under a wide range of conditions over various fundamental reactors, it was shown that the mechanism has the ability to predict the combustion process of this fuel well.

Hydrogen Application as a Fuel in Internal Combustion Engines

Hydrogen is the energy vector that will lead us toward a more sustainable future. It could be the fuel of both fuel cells and internal combustion engines. Internal combustion engines are today the only motors characterized by high reliability, duration and specific power, and low cost per power unit. The most immediate solution for the near future could be the application of hydrogen as a fuel in modern internal combustion engines. This solution has advantages and disadvantages: specific physical, chemical and operational properties of hydrogen require attention. Hydrogen is the only fuel that could potentially produce no carbon, carbon monoxide and carbon dioxide emissions. It also allows high engine efficiency and low nitrogen oxide emissions. Hydrogen has wide flammability limits and a high flame propagation rate, which provide a stable combustion process for lean and very lean mixtures. Near the stoichiometric air–fuel ratio, hydrogen-fueled engines exhibit abnormal combustions (backfire, pre-ignition, detonation), the suppression of which has proven to be quite challenging. Pre-ignition due to hot spots in or around the spark plug can be avoided by adopting a cooled or unconventional ignition system (such as corona discharge): the latter also ensures the ignition of highly diluted hydrogen–air mixtures. It is worth noting that to correctly reproduce the hydrogen ignition and combustion processes in an ICE with the risks related to abnormal combustion, 3D CFD simulations can be of great help. It is necessary to model the injection process correctly, and then the formation of the mixture, and therefore, the combustion process. It is very complex to model hydrogen gas injection due to the high velocity of the gas in such jets. Experimental tests on hydrogen gas injection are many but never conclusive. It is necessary to have a deep knowledge of the gas injection phenomenon to correctly design the right injector for a specific engine. Furthermore, correlations are needed in the CFD code to predict the laminar flame velocity of hydrogen–air mixtures and the autoignition time. In the literature, experimental data are scarce on air–hydrogen mixtures, particularly for engine-type conditions, because they are complicated by flame instability at pressures similar to those of an engine. The flame velocity exhibits a non-monotonous behavior with respect to the equivalence ratio, increases with a higher unburnt gas temperature and decreases at high pressures. This makes it difficult to develop the correlation required for robust and predictive CFD models. In this work, the authors briefly describe the research path and the main challenges listed above.

Development and characterization of a low-NOx partially premixed hydrogen burner using numerical simulation and flame diagnostics

The utilization of hydrogen as a fuel in free jet burners faces particular challenges due to its special combustion properties. The high laminar and turbulent flame velocities may lead to issues in flame stability and operational safety in premixed and partially premixed burners. Additionally, a high adiabatic combustion temperature favors the formation of thermal nitric oxides (NO). This study presents the development and optimization of a partially premixed hydrogen burner with low emissions of nitric oxides. The single-nozzle burner features a very short premixing duct and a simple geometric design. In a first development step, the design of the burner is optimized by numerical investigation (Star CCM+) of mixture formation, which is improved by geometric changes of the nozzle. The impact of geometric optimization and of humidification of the combustion air on NOx emissions is then investigated experimentally. The hydrogen flame is detected with an infrared camera to evaluate the flame stability for different burner configurations. The improved mixture formation by geometric optimization avoids temperature peaks and leads to a noticeable reduction in NOx emissions for equivalence ratios below 0.85. The experimental investigations also show that NOx emissions decrease with increasing relative humidity of combustion air. This single-nozzle forms the basis for multi-nozzle burners, where the desired output power can flexibly be adjusted by the number of single nozzles.

Laminar burning velocity blending laws using particle imaging velocimetry

One of the most essential inherent characteristics of a combustible mixture is laminar burning velocity. Because of its relevance, many methods for measuring laminar flame velocity have been devised. One advanced procedure was used to derive laminar burning velocity in a constant volume vessel for blends of iso-octane and n-heptane/air mixtures in this study: particle imaging velocimetry. Based on a precise flow field with vectors, particle imaging velocimetry (PIV) provides highly accurate laminar burning velocities. The results of the PIV method were compared with Schlieren data and simulations based on detailed LLNL gasoline surrogate chemical kinetics. It was found that the measured laminar burning velocities using the PIV method were more consistent. To predict the laminar burning velocity of the binary mixture of primary reference fuel (PRF) investigated in this study, five blending laws were used and all of them demonstrated strong application and high accuracy. The Leeds Q/k law based on the variation curve of the heat release rate/reaction process was found to have a strong predictive capability as well.