Global Flame Research Articles

Effects of Composition Heterogeneities on Flame Kernel Propagation: A DNS Study

In this study, a new set of direct numerical simulations is generated and used to examine the influence of mixture composition heterogeneities on the propagation of a premixed iso-octane/air spherical turbulent flame, with a representative chemical description. The dynamic effects of both turbulence and combustion heterogeneities are considered, and their competition is assessed. The results of the turbulent homogeneous case are compared with those of heterogeneous cases which are characterized by multiple stratification length scales and segregation rates in the regime of a wrinkled flame. The comparison reveals that stratification does not alter turbulent flame behaviors such as the preferential alignment of the convex flame front with the direction of the compression. However, we find that the overall flame front propagation is slower in the presence of heterogeneities because of the differential on speed propagation. Furthermore, analysis of different displacement speed components is performed by taking multi-species formalism into account. This analysis shows that the global flame propagation front slows down due to the heterogeneities caused by the reaction mechanism and the differential diffusion accompanied by flame surface density variations. Quantification of the effects of each of these mechanisms shows that their intensity increases with the increase in stratification’s length scale and segregation rate.

Development of a turbulent burning velocity model based on flame stretch concept for SI engines

According to the US Energy Information Administration, fossil fuels will remain the main source of energy for transportation over the next decades and thus the combustion of these fuels remains an important concern.This research studied the flame propagation under engine in-cylinder conditions and developed a correlation for turbulent burning velocity based on the global flame stretch concept. To study the impact of engine operation on flame stretch, two speeds, two loads, and three fuel-air mixtures were investigated. The flame front was determined by processing images of the flame natural luminosity.A turbulent burning velocity model was developed using dimensional analysis. The model showed that the turbulent burning velocity decreased due to flame stretching. Higher engine speeds increased the turbulent burning velocity by increasing the turbulent intensity, yet a tradeoff between the flame stretch and the turbulent burning velocity due to higher engine speed was observed. In cases where the flame distortion was very high, the flame stretch may cancel out any benefits of a large enflamed area.Incorporating the flame stretch into the burning velocity model and coupling the developed model with GT-Power simulation software revealed that the stretch may result in a 35% reduction in turbulent burning velocity.

Effect of fuel type on the MILD combustion of syngas

The MILD (Moderate or Intense Low-oxygen Dilution) combustion of four typical syngas fuels was examined in CRN (chemical reaction network) model and in parallel jet forward flow combustor. The results were presented on the thermodynamics, ignition kinetics and NO chemistry using CRN calculation. The flow field mixing was obtained from numerical simulation, the global flame signatures and exhaust emissions from experiments. The syngas fuel with higher content of inert gas (N2 and CO2) and lower concentration of active components (H2 and CO) exhibited higher mixture ignition temperature under MILD condition, as a result, greater gas recirculation ratio was required to establish the thermodynamic condition of MILD scheme. H2-enriched syngas and CO-enriched syngas showed different chemical kinetics in the ignition process of MILD mixture. In the NO chemistry under MILD condition, it was revealed that the H2 containing syngas fuels produce the NO emission mainly through the N2O-intermediate and NO-reburning mechanisms, whereas for pure H2 MILD combustion, the NNH route plays a more important role. The N2 component in the syngas fuel had physical effect in delaying the interaction between the air and fuel stream and in favoring the turbulent mixing as well as the gas recirculation. The CO2 component in the syngas fuel had chemical effect in lowering the reaction rate. The critical equivalence ratio above which MILD combustion occurs (with the reaction region covering the entire combustor) was identified for the four syngas fuels. It was observed that the syngas fuel with higher N2 and CO2 content can achieve MILD combustion at leaner condition and with lower NOx emissions. Reduced CO emission and single-digit NOx emissions were achieved for the four syngas fuels.

The role of differential diffusion during early flame kernel development under engine conditions – part II: Effect of flame structure and geometry

From experimental spark ignition (SI) engine studies, it is known that the slow-down of early flame kernel development caused by the (Le > 1)-property of common transportation-fuel/air mixtures tends to increase cycle-to-cycle variations (CCV). To improve the fundamental understanding of the complex phenomena inside the flame structure of developing flame kernels, an engine-relevant DNS database is investigated in this work. Conclusive analyses are enabled by considering equivalent flame kernels and turbulent planar flames computed with Le > 1 and Le=1. In Part I of the present study (Falkenstein et al., Combust. Flame, 2020), a reduced representation of the local mixture state was proposed for the purpose of this analysis. Fluctuations in heat release rate attributed to differential diffusion were found to be governed by the parameters local enthalpy, local equivalence ratio, and H-radical mass fraction. Here, a coupling relation for the diffusion-controlled mixture parameter local enthalpy with local flame geometry and structure is derived, characterized by the key parameters κ and |∇c|/|∇c|lam. The analysis shows that the large positive global mean curvature intrinsic to the flame kernel configuration may detrimentally affect the local mixture state inside the reaction zone, particularly during the initial flame kernel development phase. External energy supply by spark ignition may effectively bridge over this critical stage, which causes the impact of global mean flame kernel curvature to be small under the present conditions compared to the overall effect of Le ≠ 1 observed in a statistically planar flame. Once ignition effects have decayed, the mixture state inside the reaction zone locally exhibits an identical dependence on |∇c| as in a strained laminar flame. This implies that differential diffusion effects at Karlovitz numbers representative for part-load conditions are not weakened by small-scale turbulent mixing, which is undesirable for the engine application, but can be favorable in terms of modeling.

Chemical kinetic study on ignition and flame characteristic of polyoxymethylene dimethyl ether 3 (PODE3)

Polyoxymethylene dimethyl ether 3 (PODE3) is a promising diesel additive with high cetane number (78) and oxygen mass content (48%), but its ignition and flame characteristics are rarely reported. This work provides a new fundamental understanding of the ignition delay times, adiabatic flame temperature and laminar flame speed of PODE3 by detail chemical kinetic mechanism. The ignition delay time of PODE3 is lower than n-heptane (reference fuel) due to a higher global reaction rate. The ignition delay profile of PODE3 does not exhibit negative temperature coefficient (NTC) behavior and thus sensitive to temperature variation which benefits low-temperature combustion in compression ignition engines. This study discovers that the high cetane number of PODE3 guarantees a high global reaction rate, but it lacks sufficient temperature rise and active radical accumulation to act as the chemical ignition source. The oxidation reaction pathways between PODE3 and n-heptane are similar, both compose of (i) 1st O2 addition, RO2 isomerization to produce QOOH and (ii) 2nd O2 addition, (iii) ketohydroperoxide decomposition. PODE3 produces a large amount of formaldehyde due to lack of carbon-carbon bond while the n-heptane takes place β-scission to produce olefins. PODE3 has higher premixed laminar flame speed than n-heptane due to a higher global reaction rate and flame temperature. PODE3 benefits the flame sustaining at engine low load because its laminar flame speed suffers less temperature and pressure dependence. A machine learning regression model is proposed to reproduce the non-linear relationship between laminar flame speed and equivalence ratio, temperature and pressure.

Strain Rate Effects on Head-on Quenching of Laminar Premixed Methane-air flames

Head-on quenching is a canonical configuration for flame-wall interaction. In the present study, the transient process of a laminar premixed flame impinging on a wall is investigated for different strain rates, while previous studies with detailed chemistry and transport focused only on unstrained conditions. Increasing strain rate leads to a reduction in the normalized quenching distance, and an increase in the normalized wall heat flux, both are considered as global flame quantities. Looking more into the local microstructure of the quenching process, CO formation and oxidation near the wall are shifted to higher temperatures under higher strain rates. Further, the local flame structure and the thermochemical state are affected by differential diffusion driven by differences in species’ gradients and diffusivities. Quenching leads to increased species’ gradients and consequently differential diffusion is amplified near the wall compared to propagating flames. However, this effect is suppressed for increasing strain rates, which is explained in more detail by a source term analysis of the transport equation for the differential diffusion parameter ZHC. Results for the global quantities and the local flame structure show that the impact of the strain rate weakens for higher wall temperatures. Finally, the analyses of the thermo-chemical quantities in the composition space shows that H2 can be a good parameter to characterize the strain rate both for propagating and quenching flamelet.

Fuel Effects in Turbulent Premixed Pre-vaporised Alcohol/Air Jet Flames

To study combustion fundamentals of complex fuels under well-defined boundary conditions, a novel Temperature Controlled Jet Burner (TCJB) system is designed that can stabilise both gaseous or pre-vaporised liquid fuels. In a first experimental exploratory study, piloted turbulent jet flames of pre-vaporised methanol, ethanol, 2-propanol and 2-butanol mixtures are compared to methane/air as a reference fuel. Complementary one-dimensional laminar flame calculations are used to provide flame parameters for comparison. Blow-off and flame length as global flame characteristics are measured over a wide range of equivalence ratios. For fuel rich conditions, blow-off limits correlate well with extinction strain rate calculations. Differing flame lengths from lean to rich conditions are explained partly by different flame wrinkling that is assessed using planar laser-induced fluorescence imaging of the hydroxyl radical (OH-PLIF). A study of Lewis-number effects indicates that they have substantial influence on flame wrinkling. Lean alcohol/air flames, opposed to methane/air, have a Lewis-number greater than unity. This impedes curvature development, which promotes relatively large flame lengths. In contrast, across stoichiometric conditions, all alcohol/air mixture Lewis-numbers decrease significantly. At such conditions, alcohol/air flames show alike or even larger wrinkling compared to methane/air flames. However, quantitatively, the differences in flame length and wrinkling observed among the flames can neither be explained alone by Lewis-number differences, nor other global mixture parameters available from 1D laminar flame calculations. This study shall therefore emphasise the need for more detailed experimental analyses of the full thermochemical state of laminar and turbulent flames fuelled with complex fuels.

Adiabatic laminar burning velocities of C3H8-O2-CO2 and C3H8-O2-N2 mixtures at ambient conditions-PART II: Mechanistic interpretation

The effect of diluents on the laminar burning velocity of the premixed C3H8-O2-N2 and C3H8-O2-CO2 mixtures was numerically studied. Global flame parameters including adiabatic flame temperature (Tad), overall reaction order (n), activation energy (Ea), Zeldovich number (Ze) and Lewis number (Le) were calculated. Results show that the N2/CO2 alters all flame parameters. Based on asymptotic analysis for one-step overall reaction, these parameters correlates the laminar burning velocity. The change of Arrhenius effect, combination of thermal and chemical effect is the dominant factor, compared to the change of transport effect. Sensitivity analysis revealed that thermal effect is the dominant factor in Arrhenius effect. The correctness of one-step model was validated with experimental and numerical results. Detailed mechanism model analysis illustrates the linear correlations between laminar burning velocity and maximum (H + OH + O) concentration. The chemical effect of CO2 replacement of N2 in oxidizer is smaller than the thermal effect but much bigger than the transport effect in the calculation domain. The chemical effect of CO2 changes drastically with equivalence ratios and oxygen fractions.

Influence of Thickening Factor Treatment on Predictions of Spray Flame Properties Using the ATF Model and Tabulated Chemistry

Different strategies to account for the heat and mass transfer between liquid droplets and their carrier phase within the Artificially Thickened Flame (ATF) approach are analyzed and compared. Herein, two approaches are introduced to take into account the droplet movement relative to the thickened flame front orientation. While the first approach achieves this behavior through scalar modifications in the droplet temperature and mass evolution equations, the second one introduces a trajectory modification within the thickened flame front. Both approaches, referred to as projection and refraction correction, are first compared to state of the art methods in a simplified two-dimensional configuration, and then in a complex turbulent spray flame. The investigated spray flame corresponds to the operating condition EtF6 of the Sydney Spray Burner. The analysis showed that: (1) A consideration of a simplified configuration is insufficient to fully uncover the performance of the different approaches. (2) While the proposed approaches performed best in the two-dimensional configuration, only the projection method outperforms the remaining ones in the turbulent spray flame. (3) The formulation to consider the flame thickening has a strong effect on global flame properties, combustion regime distribution as well as carrier and liquid phase statistics.

Identifying the criterion for discrete flame spread over single-row birch rods

Although discrete flame spread is a common phenomenon in the practical fire scenarios, such as a group of burning trees under bushfire, research gaps still exist to address the flame spreading criteria and the related spread characteristics. Therefore, through this study, a group of birch rods with different lengths (denoted by l within 60–100 mm) and spacings (S, 1–9 mm) were analyzed experimentally and theoretically. It was known that the critical criterion of discrete flame spreading is determined by the l and S, where a criterion of l≥3d (sample thickness) could predict the critical spacing between the separated birch rods. Theoretical models were also developed to predict the global flame spread rate and mass loss rate under various S and l. The predictions based on the newly developed models agree reasonably well with those experimental data. Global flame spread rate, mass loss rate and flame height increase first and then decrease along with a bigger S, where the dimensionless flame height shows a piecewise exponential relationship with the dimensionless heat release rate. The research outcomes of this study provide a theoretical basis for the fire risk evaluation of those discrete fire spread.

Numerical Investigations of Pollutant Emissions From Novel Heavy-Duty Gas Turbine Burners Operated With Natural Gas

Abstract A numerical investigation of pollutant emissions of a novel dry low-emissions burner for heavy-duty gas turbine applications is presented. The objective of this work is to develop and assess a robust and cost-efficient numerical setup for the prediction of NOx and CO emissions in industrial gas turbines and to investigate the pollutant formation mechanisms, thus supporting the design process of a novel low-emission burner. To this end, a comparison against experimental data, from a recent experimental campaign performed by BHGE in cooperation with University of Florence, has been exploited. In the first part of this work, a Reynolds-averaged Navier–Stokes (RANS) approach on both a simplified geometry and the complete domain is adopted to characterize the global flame behavior and validate the numerical setup. Then, unsteady simulations exploiting the scale adaptive simulation (SAS) approach have been performed to assess the prediction improvements that can be obtained with the unsteady modeling of the flame. For all simulations, the flamelet generated manifold (FGM) model has been used, allowing the reliable and cost-efficient application of detailed chemistry mechanisms in computational fluid dynamics (CFD) simulation. However, FGM typically faces issues predicting flame emissions, such as NOx and CO, due to the wide range of time scales involved, from turbulent mixing to pollutant species oxidation. Specific models are typically used to predict NOx emissions, starting from the converged flow-field and introducing additional transport equations. Also CO prediction, especially at part-load operating conditions could be an issue for flamelet-based model: in fact, as the load decreases and the extinction limit approaches, a superequilibrium CO concentration, which cannot be accurately predicted by FGM, appears in the exhaust gases. To overcome this issue, a specific CO-burn-out model, following the original idea proposed by Klarmann, has been implemented in ANSYS fluent. The model allows to decouple the effective CO oxidation term from the one computed by FGM, defining a postflame zone where the source term of CO is treated following the Arrhenius formulation. In order to support the design process, an indepth CFD investigation has been carried out, evaluating the impact of an alternative burner geometrical configuration on stability and emissions and providing detailed information about the main regions and mechanisms of pollutants production. The outcomes support the analysis of experimental results, allowing an indepth investigation of the complex flow-field and the flame-related quantities, which have not been measured during the tests.

Effects of hydrogen enrichment on CH4/Air turbulent swirling premixed flames in a cuboid combustor

Effects of H2-enrichment on structures of CH4/air turbulent swirling premixed flames affected by high intensity turbulence in a gas turbine model combsutor are investigated by conducting direct numerical simulations. Two stoichiometric mixture conditions, of which volume ratio of CH4:H2 = 50:50 and 80:20, are simulated by considering a reduced chemistry (25 species and 111 reactions). Results showed qualitatively different flame shapes and reaction zone characteristics between the cases. For the higher H2-ratio case, the flame is stabilized both in the inner and outer shear layers. For the lower H2-ratio case, the flame is stabilized only in the inner shear layer and extinction occurs in the outer shear layer. Comparison of the reaction zone characteristics with unstrained and strained laminar flames in phase space showed that H2 mass fraction for the lower H2-ratio case and reaction rate profiles for both cases deviate from the corresponding laminar values. Analysis of fuel species conservation equation suggests that the turbulent transports are substantially influential to determine local and global flame structures. These findings would be useful for designing practical H2-enriched gas turbine combustor in the aspect of flame structures under high intensity turbulence.

Experimental study on combustion stability characteristics in liquid-fueled gas turbine model combustor: Fuel sensitivities and flame/flow dynamics

In this paper, combustion stability characteristics of a laboratory-scaled lean premixed prevaporized gas turbine model combustor operated with different liquid fuels were experimentally examined. Test fuels involved one linear alkane (n-dodecane), one branched alkane (iso-octane), one cyclic alkane (methylcyclohexane (MCH)) and practical multi-component RP-3 jet fuel. Tests conducted under a wide range of equivalence ratios (∅) and inlet air velocities suggested that n-dodecane flame featured the smallest (∅=0.34) lean blow out (LBO) limit, while iso-octane flame was characterized by the highest (∅=0.39). On the other hand, n-dodecane flame shifted from stable to unstable combustion at the highest equivalence ratio (∅=0.52), which is ~18% higher than the lowest case RP-3 (∅=0.44). Additional flame and flow dynamics were characterized by simultaneous high-speed OH* chemiluminescence (CL) imaging and planar particle image velocimetry (PIV) measurements. Results suggested that the instability frequency and amplitude were dependent on the fuel type and could be well related to their fundamental combustion properties. Moreover, both phase-averaged and time-resolved OH* CL imaging and PIV results demonstrated that the global unsteady flame and flow dynamics were similar for different fuels. However, a time-lag behavior was observed when iso-octane and MCH flames were subject to similar acoustic pressure oscillations in the combustor. This was speculated to be dominantly caused by their distinct ignition delay times (IDTs), which resulted in different phase lags between heat release rate and acoustic pressure oscillations. Such findings were further supported by proper orthogonal decomposition (POD) analysis performed on the simultaneously recorded OH* CL and PIV measurements.

Information-Guided Flame Detection Based on Faster R-CNN

Due to the diversity of the shape and texture of flame, and interference objects that similar to flame in color, detecting the position of flame from images is a difficult task. To enable generic object detection methods to achieve better performance in flame detection tasks, a color-guided anchoring strategy is proposed that uses color features of the flame to limit the location of the anchor. To solve the problem of high false alarm rate when directly using generic object detection methods in flame detection, a global information-guided flame detection method is proposed, this strategy uses a parallel network to generate image global information. We use these two methods to improve Faster R-CNN (Regions with Convolutional Neural Network features) to perform the fire detection process in a guided manner. Experiments on the BoWFire dataset show that our method improved detection speed by 10.1% compared with the original Faster R-CNN. In addition, the false alarm rate is decreased by 21.5%, and the overall accuracy of detection is increased by 9.3%. Experiments on PascalVOC and Corsician datasets further demonstrate the robustness of the proposed methods.

Structures of inverse jet flames stabilized on a coaxial burner

In this study we investigate different parameters used for mapping global flame structures and identify the most universal in terms of comparing flames emerging from different geometrical burner arrangements. Simultaneously the study was carried out to determine the discharge conditions yielding the blue flame of a high degree of partial premixing, and to examine the instantaneous local flame structures and mixing in the blue torch area under these conditions. In order to decouple velocity ratio and global equivalence ratio (referring to the mass flow rate of air and methane), as well as the jet velocity and Reynolds number, two different centre air nozzle diameters were studied. The results clearly indicated that the centre jet Reynolds number and global equivalence ratio are more universal parameters for inverse flame characterization than jet velocity and velocity ratio. OH-PLIF (planar laser-induced fluorescence), hot- and cold-flow acetone-PLIF were performed to provide additional information on instantaneous local flame structures and mixing in the blue torch area of the flame resembling a partially premixed flame. The PLIF results indicated that in the area of the blue torch, air and gas are well mixed by shear layer-generated vortices, and turbulences, which at this position are strongly present.

Adiabatic laminar burning velocities of C3H8-O2-CO2 and C3H8-O2-N2 mixtures at ambient conditions-PART I: Experimental and numerical study

This study and its companion paper presents a comprehensive study of laminar premixed flames of propane under oxy-fuel and oxygen-enrichment conditions for the first time. Laminar burning velocities were measured with the heat flux method at ambient conditions within an equivalence ratio of 0.6–1.6. The experimental results are discussed by comparison with modeling results from five detailed kinetic mechanisms. All models predicts the correct tendency of laminar burning velocities varies with equivalence ratios but only the UDEL model predicts the accurate laminar burning velocities under O2-CO2 atmosphere. The laminar burning velocities of C3H8-air and C3H8 + 0.3O2 + 0.7CO2were selected as reference values SL0, a new correlation SL/SL0=(1+αYenr+βYenr2) was obtained from the simulations and validated with experiment results. Good agreement between the correlation predictions and experimental results indicating that it is useful to predict SL in the range of this work. Part II will discuss the global flame parameters and the mechanisms of dilution, thermal and chemical effects of diluents on the laminar burning velocities.

A linearized error propagation method for skeletal mechanism reduction

A method of linearized error propagation (LEP) based on Jacobian analysis is developed for systematic skeletal mechanism reduction. Jacobian analysis is performed in LEP to estimate the reduction error in selected target species induced by the elimination of other species. Skeletal mechanisms are obtained by eliminating species that induce negligible worst-case errors to the target species. LEP is compared with the methods of directed relation graph (DRG) and DRG with error propagation (DRGEP) on the accuracy of reduction error estimation. It is shown that DRG can effectively control the worst-case error of every species retained in the skeletal mechanism by assuming that error may not decay in the worst cases along the graph-search paths, while it tends to overestimate the errors in the starting species, such that the skeletal mechanism can typically be further reduced if only the starting species are of interest. In contrast, DRGEP assumes geometric error decay along graph-search paths, and may overestimate the error decay and subsequently underestimate the reduction errors in species many steps away from the starting species, resulting in potential unsafe species-eliminations. Compared with DRG and DRGEP, LEP can overall more accurately estimate the errors in the target species such that smaller mechanisms can be obtained compared with DRG, while unsafe species eliminations are less likely compared with DRGEP. To demonstrate the performance of the LEP method, skeletal mechanisms are derived based on perfectly stirred reactor (PSR) solutions sampled along the S-curves, including both the ignition and the extinction states. A 35-species skeletal mechanism is obtained for ethylene−air based on the 111-species USC-Mech II, and a 146-species skeletal mechanism for n-heptane−air is obtained based on a 188-species skeletal mechanism previously developed using DRG. Validation of global flame behaviors, including PSR ignition and extinction residence time, auto-ignition delay, and laminar flame speed, shows that no significant errors are further induced by LEP.

Experimental and numerical studies on the premixed syngas swirl flames in a model combustor

Experimental and numerical investigations were performed to study the combustion characteristics of synthesis gas (syngas) under premixed swirling flame mode. Four different type of syngases, ranging from low to high H2 content were tested and simulated. The global flame structures and post emission results were obtained from experimental work, providing the basis of validation for simulations using flamelet generated manifold (FGM) modelling approach via a commercial computational fluid dynamic software. The FGM method was shown to provide reasonable agreement with experimental result, in particular the post-exhaust emissions and global flame shapes. Subsequently, the FGM method was adopted to model the flame structure and predict the radical species in the reaction zones. Simulation result shows that H2-enriched syngas has lower peak flame temperature with lesser NO species formed in the reaction zone.

Improved moth flame optimization algorithm to optimize cost-oriented two-sided assembly line balancing

Purpose This paper aims to propose an improved Moth Flame Optimization (I-MFO) algorithm to optimize the cost-oriented two-sided assembly line balancing (2S-ALB). Prior to the decision to assemble a new product, the manufacturer will carefully study and optimize the related cost to set up and run the assembly line. For the first time in ALB, the power cost is modeled together with the equipment, set up and labor costs. Design/methodology/approach I-MFO was proposed by introducing a global reference flame mechanism to guide the global search direction. A set of benchmark problems was used to test the I-MFO performance. Apart from the benchmark problems, a case study from a body shop assembly was also presented. Findings The computational experiment indicated that the I-MFO obtained promising results compared to comparison algorithms, which included the particle swarm optimization, Cuckoo Search and ant colony optimization. Meanwhile, the results from the case study showed that the proposed cost-oriented 2S-ALB model was able to assist the manufacturer in making better decisions for different planning periods. Originality/value The main contribution of this work is the global reference flame mechanism for MFO algorithm. Furthermore, this research introduced a new cost-oriented model that considered power consumption in the assembly line design.

Nonlinear flame response dependencies of a V-flame subjected to harmonic forcing and turbulence

We study the dependence of the flame sheet response of an open V-flame when subjected to simultaneous but independently controlled – (1) narrowband, coherent disturbances, (2) mean flow velocity, and (3) turbulent broadband disturbances. We re-examine the data presented in Humphrey et al. (2018). Flame edge and flow field were obtained from Mie scattering images and PIV vector fields, respectively. We determine the flame sheet response, which allows us to understand the effects of kinematic restoration on the local and global flame dynamics. We find some highly nonlinear behaviors in the flame sheet response, which have not been reported previously. In particular, we observe (1) oscillations in the rise and peak region of the flame response, and (2) early onset of the nonlinear coupling between narrowband and broadband disturbances, resulting in oscillatory decay immediately downstream of the flame holder region. The spatial oscillations seen in the flame response arise only when unalike disturbances such as vortical and flame wrinkle disturbances have a comparable wavelength and, thus, interfere. We then find that higher nominal velocity and turbulent intensities increase asymmetry in the flame response, and subsequently affect the local and global heat release response (HRR). We analytically calculate HRR from flame sheet response. We find that there is a monotonic increase in the response with increasing flame length for lower nominal velocities, possibly due to higher flame symmetry. Moreover, the HRR calculated from flame sheet response captures the effect of kinematic restoration very well. Notably, there is a decrease in HRR with increasing turbulence intensity due to enhanced smoothing from kinematic restoration at higher turbulence levels. We further find that the flame response dependence on harmonic forcing manifest in the low-pass filter characteristics of the global HRR response.