Flame Characteristics Research Articles

Effects of adding n-amyl alcohol, dimethylfuran to fuel on soot formation in aviation kerosene diffusion flame

As the main energy consumption of aviation and aerospace, the study of combustion characteristics of aviation kerosene is of great significance. In this paper, through the self-built experimental system, the combustion flame characteristics of pure aviation kerosene, aviation kerosene mixed with n-amyl alcohol, aviation kerosene mixed with dimethylfuran were studied under different working conditions, and the physicochemical properties of soot particles generated in the flame, and the effects of mixing n-amyl alcohol and dimethylfuran on the formation of soot particles were analyzed from the microscopic perspective. The results show that: 1. The soot particles in the combustion of aviation kerosene mixed with n-amyl alcohol and dimethylfuran show some characteristics of amorphous structure, unclear outline and incomplete curing; 2. Under K-D20 condition, nitrates are included in particulate matter generated by soot; 3. After mixing n-amyl alcohol and dimethylfuran, the degree of graphitization continues to decrease.

Construction of boron-based double-layer core-shell structure composites and their combustion energy release characteristics

Although boron (B) powder has a high energy density, the high boiling point oxide layer (B2O3) on the surface seriously hinders the combustion of internal B particles, which further limits the use of B powder. In order to solve this issue, polydopamine (PDA) was used as a sandwich layer (sandwich layer used to connect solid-liquid interface) between the original B powder and liquid perfluoropolyether (PFPE), and then a double-layer core-shell structure B@PDA@PFPE was prepared through the electrostatic self-assembly method. Herein, PDA not only helps remove naturally occurring B2O3, but also provides more active sites and improves the reactivity of B and PFPE. The results indicate that the B@PDA@PFPE has excellent combustion flame and energy release characteristics due to the superior dispersion and reactivity of PFPE. Compared to that of the original B powder, the results of thermal decomposition and combustion heat of B@PDA@PFPE with 30%PFPE discloses that the oxidation temperature drops by about 19.5 ℃, the combustion efficiency rises by about 22.3 %, and the flame expansion rate and flame temperature rise by approximately 40 times and 95.6 ℃, respectively. Therefore, the construction of double-layer core-shell structure effectively promotes the combustion of B powder. This work provides a new strategy for the application of B powder.

Composite combustion behaviors of tubular flame and central jet flame in a reduced-diameter vortex combustor

The characteristics of the tubular flame and the flow field mixing mechanism in a reduced-diameter vortex combustor are investigated by varying the fuel flow rate and equivalence ratio through experiments and numerical simulations. Single-layer tubular flame and double-layer composite tubular flame are found in the combustor under the coupling effect of the cyclone and the central jet. The composite tubular flame will be formed when the air in the combustor is more abundant (Ф>1.00), and the center flame frequency is linearly and positively correlated with the Reynolds number of the central jet air. When the Reynolds number exceeds 2000, the double-layer composite flame tends to stabilize, with the center flame frequency higher than 9 Hz. The turbulence of the central jet air promotes the mixing of reactants by enhancing the recirculation near the nozzle, guaranteeing the central flame's stable combustion. Through analysis of the burn rate of methane at the outlet and the emission species of CO and CO2, it is evident that the double-layer flame achieves the methane burn rate exceeding 95 %, while also exhibiting lower CO emissions compared to the single-layer flame.

Experimental research on dynamic response characteristics of lean premixed flame excited by acoustic standing wave

The compact combustor holds great potential in the aerospace field. However, it faces challenges in terms of interaction between acoustic waves and flames, which affects combustion efficiency and intensity. In this study, the dynamic response of lean premixed flames under the excitation of a transverse standing wave acoustic field with different frequencies and amplitudes. The results indicate that the flame's response frequency is consistent with the excitation frequency. Decreasing the sound wave frequency and increasing the sound amplitude both lead to an increase in flame area oscillation, thereby enhancing the heat release rate. However, excessively high sound pressure values can enhance fuel diffusion, resulting in a reduction in flame area or even local flame extinction, which significantly decreases flame intensity. This research provides valuable insights into the behavior of lean premixed flames under acoustic excitation, contributing to the optimization of combustion processes and improvement of efficiency and performance in compact combustors.

Active Control of Longitudinal Combustion Instability in Bluff-Body Stabilized Premixed Flames with Multiple Neural Network Controller

ABSTRACT The suppression performance of multiple neural network controller on the longitudinal combustion instability is investigated in the Volvo bluff-body stabilized premixed flame. Two controlled plant models, e.g. one-dimensional (1D) reduced order acoustic network model and three-dimensional (3D) large eddy simulation model are adopted to verify this control strategy. In order to build the reduced order Volvo acoustic network model, large eddy simulation is adopted to extract the characteristics of system heat release under wide bandwidth and construct the flame transfer functions. For the 1D acoustic network model, this controller can completely eliminate the pressure oscillation using fuel valve as actuator. For the 3D large eddy simulation model that mimics the real-time oscillating characteristics, clustered prediction method and amplitude limiting method are adopted in multiple neural network control strategy to better account for the nonlinear characteristics of the 3D Volvo flame. This control strategy enables the modulation of the phase relationship between the heat release rate oscillation and pressure oscillation by introducing small perturbations to the inlet equivalence ratio, and attenuates the amplitude of the second harmonic of the unstable mode effectively.

DCP-Net: An Efficient Image Segmentation Model for Forest Wildfires

Wildfires usually lead to a large amount of property damage and threaten life safety. Image recognition for fire detection is now an important tool for intelligent fire protection, and the advancement of deep learning technologies has enabled an increasing number of cameras to possess functionalities for fire detection and automatic alarm triggering. To address the inaccuracies in extracting texture and positional information during intelligent fire recognition, we have developed a novel network called DCP-Net based on UNet, which excels at capturing flame features across multiple scales. We conducted experiments using the Corsican Fire Dataset produced by the “Environmental Science UMR CNRS 6134 SPE” laboratory at the University of Corsica and the BoWFire Dataset by Chino et al. Our algorithm was compared with networks such as SegNet, UNet, UNet++, and PSPNet, demonstrating superior performance across three metrics: mIoU, F1-score, and OA. Our proposed deep learning model achieves the best mIoU (78.9%), F1-score (76.1%), and OA (96.7%). These results underscore the robustness of our algorithm, which accurately identifies complex flames, thereby making a significant contribution to intelligent fire recognition. Therefore, the proposed DCP-Net model offers a viable solution to the challenges of wildfire monitoring using cameras, with hardware and software requirements typical of deep learning setups.

Experimental Investigation on the Effect of Heating Oil and Tyre Pyrolysis Oil Combustion in an Evaporative Combustion Chamber

This research aims to delve into the intricacies of combustion processes, specifically focusing on heating oil and a blend of heating oil with Tire Pyrolysis Oil (TPO) in a self-developed evaporative combustion chamber featuring steam injection. The primary objective is to scrutinize the impact of steam injection on the combustion dynamics. Conducting a series of tests, the investigation involved the meticulous manipulation of stoichiometric ratios while introducing ambient air through gravity fuel flow. Subsequent iterations of these tests incorporated the introduction of steam into the ambient air stream. The examination encompassed the combustion of both heating oil and the TPO blend within the combustion chamber. The evaluation criteria comprised an in-depth analysis of flame characteristics, temperature distribution within the combustion chamber, and the quantification of emissions such as particulate matter (PM), nitrogen oxides (NOx), carbon dioxide (CO2), carbon monoxide (CO), and water vapor (H2O). Throughout the experimentation phase, commercially available diesel fuel served as the primary fuel source. To facilitate the tests, the combustion chamber under scrutiny was seamlessly integrated into an AVL engine test bench system. Essential parameters, including fuel consumption, were meticulously gauged using an AVL 735 fuel flow meter, while fuel temperature was monitored using the AVL 745 fuel temperature conditioning system. The intake air, a crucial element in the combustion process, was quantified with precision using an AVL Flowsonix sensor. Emission measurements were conducted meticulously using state-of-the-art equipment, with gaseous emissions analyzed using an AVL FTIR AMA i60 exhaust gas analyzer. Simultaneously, soot emissions were quantified through employment of an AVL Micro Soot sensor. This comprehensive approach not only delves into the fundamental aspects of combustion but also extends its reach to the exploration of innovative techniques, such as steam injection, to enhance combustion efficiency and reduce emissions. The integration of advanced measurement tools ensures a robust and thorough analysis of the combustion process and its environmental implications.

Understanding the mechanisms of flame quenching and flame-wall interactions in microchannel

The flow resistance and quenching characteristics of hydrogen flame in the microchannel of corrugated plates under a nitrogen environment are investigated in this paper. The analysis reveals that the explosion pressure and flame velocity decrease as the aperture of the microchannel decreases. Adding 24 % nitrogen increased the hydrogen quenching diameter from 0.5 mm to 1.4 mm in the case of the stoichiometric ratio. In light of the impact of nitrogen and microchannel characteristics, a critical flame velocity prediction formula for hydrogen flames has been established. To clarify the flame quenching mechanism, kinetic simulations and heat transfer calculations are conducted. The flow resistance and quenching temperature under different microchannel diameters are obtained. As the microchannel aperture decreases and the nitrogen concentration increases, the quenching temperature of hydrogen rises. Combined with the exothermic reaction and the heat transfer of microchannel, the flame-wall heat transfer in the microchannel is analyzed in detail. A reduction in the diameter of microchannels is beneficial in terms of enhancing the flame-wall interaction, and promote the thermal and free radical quenching of hydrogen flame. The results can be employed to elucidate the mechanism of hydrogen flame quenching and to reduce the thermal runaway hazard of hydrogen.

Analytical assessment of hetero-/homogeneous combustion of magnesium particle: Fully explicit formulas for flame characteristics

In this study, by proposing a comprehensive multi-step model, the combustion of magnesium particles in O2-He, O2-Ar, and O2-N2 is scrutinized. In the current model, both the heterogeneous and homogeneous combustions are considered and the process is divided into four stages solid, liquid, and gas combustion and melting. Moreover, the diffusions of oxygen and unreacted magnesium to droplet and infinity together with surface exothermic reaction are considered. The governing equations are analytically solved and then, the formulas are extracted for combustion time and temperature, flame standoff distance, and evaporation rate as the functions of particle diameter, ambient temperature and pressure, oxygen mass fraction, type of inert gas, and Lewis numbers. For 120 µm particle and oxygen content of 0.05, time contributions of homogeneous and heterogeneous combustions are 85.8% and 14.2%, respectively. The burning time has drastic changes at ambient pressures below l atm, so that the burning time variations relative to the pressure in the environments less than 1 atm and greater than it are equal to 1200–1550 and 70–90 ms/atm, respectively. When the oxygen mass fraction is less than 0.29, combustion in helium-oxygen ends earlier than that in O2-Ar and O2-N2, but for the mass fraction greater than 0.35, it has the longest burning time.

Experimental Investigation and Theoretical Analysis of Flame Spread Dynamics over Discrete Thermally Thin Fuels with Various Inclination Angles and Gap Sizes

Flame spread over discrete fuels is a typical phenomenon in fire scenes. Experimental and theoretical research on flame spread over discrete thermally thin fuels separated by air gaps with different inclination angles was conducted in the present study. Experiments with six inclination angles ranging from 0° to 85° and various fuel coverage rates from 0.421 to 1 were designed. The flame spread behavior, the characteristic flame size, and the flame spread rate were analyzed. The results show that the flow pattern, stability, and flame size exhibit different characteristics with different inclination angles and gap sizes. As the inclination angle increases, particularly with smaller gaps, turbulent and oscillating flames are observed, while larger gap sizes promote flame stability. The mechanism of flame propagation across the gap depends on the interplay between the flame jump effect and heat transfer, which evolves with gap size. Average flame height, average flame width, and flame spread rate initially increase and then decline with the increase in fuel coverage, peaking at fuel coverage rates between 0.93 and 0.571 for different inclination angles. A theoretical model is proposed to predict the flame spread rate and the variation in the flame spread rate with inclination angle and fuel coverage. Furthermore, the map determined by inclination angle and fuel coverage is partitioned into distinct regions, comprising the accelerated flame spread region, the flame spread weakening region, and the failed flame spread region. These findings provide valuable insights into flame spread dynamics over discrete thermally thin fuels under diverse conditions.

Flame structure and stability for gradient magnetic field enhanced non-premixed combustion of highly diluted methane with nitrogen

Efficient utilization of low calorific value fuels is challenging due to their limited burning rates and stability. This study explored the use of upward-increasing magnetic fields as a novel approach to enhance flame stability in such conditions, focusing on non-premixed highly diluted methane flames with nitrogen. Employing a vertical burner, magnetic intensities were varied to observe their impact on laminar jet diffusion flames. This research revealed that the gradient magnetic fields significantly modify flame characteristics. At lower magnetic intensities, the influence on flame structure, temperature, and stability was minimal. However, as magnetic intensity increased, notable changes in flame features such as height, shape, and thermal distribution were observed, suggesting a threshold intensity beyond which the magnetic influence becomes pronounced. The research further demonstrated that gradient magnetic fields could enhance the blow-out concentration limit, indicating an effective strategy for managing combustion in diluted fuels. The findings provide valuable insights into magnetic fields' role as a control mechanism, offering potential advancements in combustion technology and contributing to the broader pursuit of energy efficiency and reduced emissions in industrial applications.

The asymptotic solution of near-limit chain-branching premixed flames with the Zel’dovich–Liñán two-step mechanism in the linear and fast recombination regime

Near-limit characteristics of chain-branching premixed flames is investigated numerically and asymptotically by employing the Zel’dovich–Liñán two-step mechanism with linear and (sufficiently) fast recombination, for which both chain-branching and -recombination steps take place in a thin reactive layer of O(β−1), with β being the chain-branching Zel’dovich number. The numerical and asymptotic results reveal that the rate-ratio eigenvalue r between the chain branching and recombination steps approaches a minimum critical value of rmin→e as the chain-recombination step becomes infinitely fast. The existence of the finite asymptotic value of r=e indicates that no steadily propagating flame solution can be found for fuel concentrations lower than its critical value, corresponding to the criticality of r=e, thereby explaining the (lean) flammability limit. This intrinsic flammability characteristics with linear recombination is the most outstanding contrast to the quadratic recombination counterpart, for which flammability is achieved only with external heat loss added to the model.Novelty and significance statementNear-limit combustion characteristics of chain-branching flames is investigated numerically and asymptotically by employing the Zel’dovich–Linan two-step chemical kinetics with linear and fast recombination. This work demonstrates that the rate-ratio eigenvalue between the chain-branching and -recombination steps asymptotically approaches a critical minimum value, corresponding to the flammability limit. The existence of flammability limit with the linear recombination is found to be the most significant contrast to the quadratic recombination model, which is incapable of predicting flammability limit. By this study, a formal asymptotic procedure, by which the crossover temperature and lean flammability limit condition can be determined without assuming a steady-state approximation of intermediate species, is established and can be applied to analyze flame structures with multi-step reduced mechanisms.

The impact of H2 and O2 enrichment on the laminar combustion characteristics of biomass syngas flame

This article investigates the impact of H2 and O2 enrichment on the laminar burning velocity (SL) of syngas in a constant-volume combustion chamber. By analyzing changes in both chemical and thermal effects, it examines the impact of variations in H2 and O2 content on the SL independently. Furthermore, this article investigates the pressure variations of spherical expanding flames, flame instability, and the formation of mixed fuel NO. Results show increased H2 and O2 content enhance SL, with O2 addition leading to a linear increase. H2 affects thermal-diffusive instability differently in lean and rich fuel regions, while increasing O2 content mitigates it. The synergistic influence of flame thickness and thermal expansion ratio amplifies fluid dynamic instability with higher H2 and O2 content. O2 addition is more effective in promoting the rate of production for thermal NO and H2 addition is more effective in promoting the rate of production for non-thermal NO.

Study on flame quenching characteristics inside the Tesla valve structure flame arrester unit

Flame arrester is a kind of safety device designed to prevent the spread of flames. In order to achieve a more efficient flame arrester unit structure, this paper proposes a flame arrester unit based on the Tesla valve structure. A comparative study of the quenching characteristics of deflagration flames of propane-air premixtures in traditional crimped ribbon and Tesla valve structure flame arrester units is conducted through numerical simulations and experiments. The results indicate that the flame arrester unit based on the Tesla valve structure exhibits more efficient flame quenching performance compared to the crimped ribbon flame arrester unit. The flame quenching process fusion image shows that the flame quenching length of Tesla valve flame arrester unit with the same cross-sectional area is only 61% of the crimped ribbon flame arrester unit. In addition to heat transfer and wall effect, the collision of airflow in the branched pipe and main pipe within the Tesla valve structure flame arrester unit also plays a significant role in hindering the further advancement of flames. The quenching process of the Tesla valve structure flame arrester unit can be divided into four stages: expansion, diversion, convergence, and contraction stages. Among the five structural parameters that make up the Tesla valve structure flame arrester unit, the angle is the most critical factor affecting quenching performance, with the angle and entrance structure having a significant impact on flow performance. Furthermore, experimental evidence confirms the typical morphological changes the flame front structure undergoes during flame propagation: spherical (hemispherical),finger-shaped and tulip-shaped. However, tulip-shaped flames do not always propagate continuously to the end of the pipeline.

Experimental investigation of the effect of air/fuel ratio change on JP8 swirl flame characteristics with image processing methods

In this study, the stable combustion ranges and emission values of JP8 fuel, which is used in military aviation, were tested and optimum conditions were determined. The AFR (Air/Fuel Ratio) of the JP8 flame was increased experimentally at constant thermal power in a gas turbine combustion chamber. In the study, AFR were tested as 30/1, 33/1, 36/1, 39/1 and 42/1. A generator with 0.4 swirl number is placed at the burner outlet. Under these conditions, the effect of external acoustic enforcement frequencies on dynamic instabilities at different AFR was investigated. Flame length and thickness data were extracted from the images obtained from the image processing technique. The effect of AFR change on the combustion chamber temperature was examined and pollutant emissions were measured. The results showed that the most stable flame appeared in AFR 33/1 case at 155 and 300 Hz resonance frequencies under acoustic enforcements. Additionally, when the AFR was increased to 42/1, flame instability increased at all frequency values. Moreover, it has been determined that the most optimum mixture in terms of combustion chamber exit temperature and CO emissions is AFR 33/1. There was an increase in NOX emissions by up to 39/1 with the increase in AFR.

Flame characteristics and NO emission behaviors of methane/ammonia counterflow premixed flames with opposed N2 or air stream

Behaviors of methane/ammonia counterflow premixed flames and NO emission are numerically and experimentally investigated with opposed N2 or air stream by varying strain rate (ag) and equivalence ratio (ϕ). The premixed stream is 80% methane and 20% ammonia by volume mixed with air considering the utilization of ammonia by blending hydrocarbon fuels. The opposed stream is either N2 or air considering the potential application in gas turbines having single- or two-stage combustion. The simulations are conducted by increasing ag up to flame extinction for a specified ϕ and an experiment is conducted to evaluate various kinetic mechanisms. The extinction strain rate increases monotonically with ϕ with opposed air stream (AS), while increases and then decreases with opposed nitrogen stream (NS). The extinction mechanisms are explained by adopting the concepts of the local equilibrium temperature and heat loss ratio. For lean and rich mixtures with NS and lean mixtures with AS, the extinction occurs due to comparable effects of incomplete reaction and heat loss from the flame to the downstream burnt region. While for rich mixtures with AS, the extinction is attributed mainly to incomplete reaction. The contribution of thermal NO as compared with prompt NO in NO production is weak for all cases with NS and AS. The emission index (EINO) for lean and rich mixtures with NS and for lean mixtures with AS decreases monotonically with the increase of strain rate for all ϕ. Increasing equivalence ratio at a specified ag decreases NO production for lean and rich mixtures with NS and lean mixtures with AS. While for rich mixtures with AS, the EINO increases monotonically with ag. From the reaction pathway analysis, for lean mixtures, the effect of increasing ag on the reduction of NO production is attributed by weakening NH-related reaction paths, while NH2-related reaction paths change little. When ϕ increases for a specified ag with NS, NO production is reduced by weakening NH2-related reaction paths and strengthening NH-related reaction paths. For rich mixtures with AS, increasing ag increases NO production by strengthening NH2-related reaction paths.

Evaluation of flow and flame characteristics of turbulent bluff-body CH4-H2 flame using LES-FPV approach

ABSTRACT This study investigated the flow and flame structure of a bluff-body stabilised CH4-H2 flame using the large eddy simulation (LES) and the flamelet progress variable (FPV) model. The performance of three subgrid-scale (SGS) LES models, i.e. the standard Smagorinsky model (SSM), the wall-adapting local eddy viscosity (WALE) model, and the dynamic Smagorinsky model (DSM) in predicting turbulent and reactive flow characteristics was assessed. Parameters, namely y+ , Pope index (M), vorticity field, and resolved turbulent kinetic energy (kt ), were analysed to determine the predictive capability of the three models. The results demonstrated that DSM and WALE successfully resolved 80% of kt for chosen grid configurations, whereas SSM exhibited discrepancies. The overall trends captured by all three models matched well with the experimental trend with DSM and WALE outperforming SSM in predicting reacting flow fields in the recirculation zone, while SSM produced better predictions in the regions away from the recirculating zone.

Experimental investigation on morphology of window-ejected flame without facade effect

As the key characteristic of window-ejected flames, flame morphology such as flame height, flame depth involves the ignition of surrounding buildings. This article experimentally investigated the flame height, the maximum flame width and the maximum flame depth ejected from a fire compartment without the facade wall effect. A small-scale compartment with a sidewall opening attached to compartment top is used for simulating the situation without the facade wall. The ejected flame height, maximum flame width and maximum flame depth were recorded and measured for various opening sizes and fuel supply rates. Results show that: (1) The ejected flame height increases as the increase of fuel supply rate and decreases as the increase of opening dimension, and was obviously lower than that with the facade effect; (2) The maximum flame width increases as the increase of fuel supply rate and decreases with the increase of opening dimension, and was higher than that with the facade effect; (3) The maximum flame depth increases as the increase of fuel supply rate, and the formation of maximum flame depth was analyzed based on the ejected thermal plume momentum and the air entrainment momentum. A dimensionless parameter, which presents the complex competition mechanism between the plume momentum and the air entrainment momentum, was proposed to characterize their impacts on flame depth, by which the maximum flame depth was represented well. This work would provide theoretical support for building fire prevention and control.

Experimental study on flame behavior and heat transfer mechanism of ethanol spill fire in tunnels under upwind and downwind environment

The primary objective of this work was to examine the influence of wind speed and wind direction, specifically upwind and downwind, on the flame characteristics, heat transfer processes, and burning rate laws of ethanol spill fires within a tunnel environment. The findings reveal that the flame height is initially controlled by the by the discharge rate, which ultimately transitions to being controlled by longitudinal ventilation. As wind speed escalates in upwind conditions, the combustion area first decreases and then increases, whereas in downwind scenarios, it first increases and then decreases. Convection emerges as the predominant thermal feedback mechanism for spill fires in windy conditions, particularly exhibiting heightened intensity in downwind environment. It is noteworthy that between 20% and 45% of the heat within the fuel layer dissipates through conduction and convection between the fuel and its substrate, with downwind environments experiencing heightened heat loss; approximately 90% of this heat loss in ethanol spill fires is attributed to conduction. These disparities in heat transfer processes ultimately culminate in a higher burning rate for spill fires in upwind environments compared to downwind counterparts.

Experimental investigation for temperature and emissivity by flame emission spectrum in a cavity of rocket based combined cycle combustor chamber

Flame temperature and spectral emissivity were the important parameters characterizing the sufficient degree of fuel combustion and the particle radiative characteristics in the Rocket Based Combined Cycle (RBCC) combustor. To investigate the combustion characteristics of the complex supersonic flame in the RBCC combustor, a new radiation thermometry combined with Levenberg-Marquardt (LM) algorithm and the least squares method was proposed to measure the temperature, emissivity and spectral radiative properties based on the flame emission spectrum. In-situ measurements of the flame temperature, emissivity and spectral radiative properties were carried out in the RBCC direct-connected test bench with laser-induced plasma combustion enhancement (LIPCE) and without LIPCE. The flame average temperatures at fuel global equivalence ratio (α) of 1.0b and 0.6 with LIPCE were 4.51% and 2.08% higher than those without LIPCE. The flame combustion oscillation of kerosene tended to be stable in the recirculation zone of cavity with the thermal and chemical effects of laser induced plasma. The differences of flame temperature at α = 1.0b and 0.6 were 503 K and 523 K with LIPCE, which were 20.07% and 42.64% lower than those without LIPCE. The flame emissivity with methane assisted ignition was 80.46% lower than that without methane assisted ignition, due to the carbon-hydrogen ratio of kerosene was higher than that of methane. The spectral emissivities at 600 nm with LIPCE were 1.25%, 22.2%, and 4.22% lower than those without LIPCE at α = 1.0a (with methane assisted ignition), 1.0b (without methane assisted ignition) and 0.6. The effect of concentration in the emissivity was removed by normalization to analyze the flame radiative properties in the RBCC combustor chamber. The maximum differences of flame normalized emissivity were 50.91% without LIPCE and 27.53% with LIPCE. The flame radiative properties were stabilized under the thermal and chemical effects of laser induced plasma at α = 0.6.