Combustion characteristics of H2/N2 and H2/CO syngas nonpremixed flames

Turbulent nonpremixed H₂/N₂ and H₂/CO syngas flames were simulated using 3D large eddy simulations coupled with a laminar flamelet combustion model. Four different syngas fuel mixtures varying from H₂-rich to CO-rich including N₂ have been modelled. The computations solved the Large Eddy Simulation governing equations on a structured non-uniform Cartesian grid using the finite volume method, where the Smagorinsky eddy viscosity model with the localised dynamic procedure is used to model the sub-grid scale turbulence. Non-premixed combustion has been incorporated using the steady laminar flamelet model. Both instantaneous and time-averaged quantities are analysed and data were also compared to experimental data for one of the four H₂-rich flames. Results show significant differences in both unsteady and steady flame temperature and major combustion products depending on the ratio of H₂/N₂ and H₂/CO in syngas fuel mixture.     

Investigation of dilution effects on partially premixed swirling syngas flames using a LES-LEM approach

The dilution effects of CO₂ and H₂O on partially premixed swirling syngas flames are investigated with the large eddy simulation (LES) method. The linear-eddy model (LEM) is employed to directly resolve the unclosed molecular diffusion, scalar mixing and chemical reaction processes occurring at subgrid scale level using their specific length and time scales instead of modelling, which makes the LES-LEM approach quite attractive for hydrogen fuel combustion as the obviously different diffusion and reaction characteristics of H₂ and H compared to other species in the syngas mixture. Firstly, adding CO₂ into the fuel stream can significantly decrease the flame temperature during the partially premixed combustion. The concentration of H and OH radicals decreases upon CO₂ dilution and thus the chemical reaction processes are modified. Compared with CO₂, H₂O is less effective in changing the temperature field because of the chemical effects of H₂O. The simultaneous addition of H₂O and CO₂ as dilution gases with volume ratio 1:1 into the fuel stream is also conducted to identify the effects of H₂O and CO₂ on partially premixed combustion dynamics by comparing with single H₂O and CO₂ cases. The obtained results are expected to provide helpful information for the design and operation of gas turbine combustion systems with syngas fuels.     

Effect of radiation emission and reabsorption on flame temperature and NO formation in H2/CO/air counterflow diffusion flames

The radiation effect on flame temperature and NO emission of H₂-lean (0.2H₂ + 0.8CO) and H₂-rich (0.8H₂ + 0.2CO) syngas/air counterflow diffusion flames was numerically investigated using OPPDIF code incorporated with the optical thin model, statistical narrow band model and adiabatic condition. Firstly, the coupled effect of strain rate and radiation was studied. Disparate tendencies of NO emission with an increasing strain rate between H₂-lean and H₂-rich syngas flames were found at very small strain rate, and the effect of radiation reabsorption on NO formation can be neglected when the strain rate was greater than 100 s^?1 for both H₂-lean and H₂-rich syngas flames. Because the radiation effect is vital to flames with small strain rate, its impact on flame temperature and NO emission was investigated in detail at a strain rate of 10 s^?1. The results indicated that NO formation is more sensitive to radiation reabsorption than flame temperature, especially for the H₂-rich syngas flame. The underlying mechanism was discovered by using reaction pathway analysis. Furthermore, the radiation effect under CO₂ dilution of the syngas fuel was examined. It was demonstrated that the radiation effect on flame temperature became more prominent with the increase of CO₂ concentration for both H₂-lean and H₂-rich syngas. The radiation effect on NO emission increased first and then decreased with an increasing CO₂ content for H₂-lean syngas, whereas for H₂-rich syngas the radiation effect is monotonic.     

Effects of hydrogen addition on structure and NO formation of highly CO-Rich syngas counterflow nonpremixed flames under MILD combustion regime

The present study has numerically investigated the Moderate or Intense Low oxygen Dilution (MILD) combustion regime, combustion processes and NO formation characteristics of the highly CO-rich syngas counterflow nonpremixed flames. To realistically predict the flame properties of the highly CO-rich syngas, the chemistry is represented by the modified GRI 3.0 mechanism. Computations are performed to precisely analyze the flame structure, NO formation rate, and EINO of each NO sub-mechanism. Numerical results reveal that the hydrogen enrichment and oxygen augmentation substantially influence the NO emission characteristics and the dominant NO production route in the CO-rich syngas nonpremixed flames under MILD and high temperature combustion regimes. It is found that the most dominant NO production routes are the NNH path for the lowest oxygen level (3%) and the thermal mechanism for the highest O₂ condition (21%). For the intermediate oxygen level (9%), the most dominant NO production routes are the NNH route for the hydrogen fraction up to 5%, the CO₂ path for the hydrogen fraction range from 5% to 10% and the thermal mechanism for the hydrogen fraction higher than 10%, respectively. To evaluate the contribution of the specific reaction on EINO the sensitivity coefficients are precisely analyzed for NO formation processes with the dominance of NNH/CO₂/Thermal mechanism under the highly CO-rich syngas flames.     

Numerical modeling for structure and NOx formation characteristics of oxygen-enriched syngas turbulent non-premixed jet flames

The present study numerically investigated the effect of oxygen enrichment on the precise structure and NO_x formation characteristics of turbulent syngas non-premixed flames. The turbulence-chemistry interactions were represented by a Lagrangian flamelet model. In context with the Lagrangian flamelet model, the NO concentration was obtained directly from the flamelet calculation based on full NO_x chemistry, with radiative heat loss being accounted for through the flamelet energy equation. Computations were performed for three different syngas compositions with a designated nitrogen dilution level. Numerical results indicated that, for the CO-rich composition with the lowest LHV yielding the highest scalar dissipation rate and shortest flight time, the flame structure was dominantly influenced by turbulence-chemistry interactions. On the other hand, with regard to the H₂-rich composition with the highest LHV yielding the lowest injection velocity and longest flight time, the flame structure was strongly influenced by radiative cooling. The peak NO level was remarkably elevated by increased oxygen level due to the elevated temperature of the oxygen-enriched flame. In the enhanced oxygen level (30%), the H₂-rich case produced the highest NO level due to a higher temperature and longer residence time within the hot flame zone, while the CO-rich case yielded the lowest NO level due to a lower temperature and shorter residence time. It was also found that, by enhancing the oxygen level, contributions of NNH and N₂O to total NO emission rapidly decreased while the contributions of the thermal NO path were progressively dominant for all cases.     

Turbulent flame topology and the wrinkled structure characteristics of high pressure syngas flames up to 1.0 MPa

The turbulent flame topology characteristics of the model syngas with two different hydrogen ratios were statistically investigated, namely CO/H₂ ratio at 65/35 and 80/20, at equivalence ratio of 0.7. The combustion pressure was kept at 0.5 MPa and 1.0 MPa, to simulate the engine-like condition. The model syngas was diluted with CO₂ with a mole fraction of 0.3 which mimics the flue gas recycle in the turbulent combustion. CH₄/air flame with equivalence ratio of 1.0 was also tested for comparison. The flame was anchored on a premixed type Bunsen burner, which can generate a controllable turbulent flow. Flame front, which is represented by the sharp increased interface of the OH radical distribution, was measured with OH-PLIF technique. Flame front parameters were obtained through image processing to interpret the flame topology characteristics. Results showed that the turbulent flames possess a wrinkled character with smaller scale concave/convex structure superimposed on a larger scale convex structure under high pressure. The wrinkled structure of syngas flame is much finer and more corrugated than hydrocarbon fuel flames. The main reason is that scale of wrinkled structure is smaller for syngas flame, resulting from the unstable physics. Hydrogen in syngas can increase the intensity of the finer structure. Moreover, the model syngas flames have larger flame surface density than CH₄/air flame, and hydrogen ratio in syngas can increase flame surface density. This would be mainly attributed to the fact that the syngas flames have smaller flame intrinsic instability scale l_i than CH₄/air flame. S_T/S_L of the model syngas tested in this study is higher than CH₄/air flames for both pressures, due to the high diffusivity and fast burning property of H₂. This is mainly due to smaller L_M and l_i. V_f of the two model syngas is much smaller than CH₄/air flames, which suggests that syngas flame would lead to a larger possibility to occur combustion oscillation.     

Hydrogen-enriched non-premixed jet flames: Compositional structures with near-wall effects

The species concentrations of non-premixed hydrogen and syngas flames were examined using results obtained from direct numerical simulation technique with flamelet generated manifold chemistry. Flames with pure H₂ and H₂/CO mixtures are discussed for an impinging jet flame configuration. Single-point data analyses are presented illustrating the effects of fuel composition on species concentrations. In general, scatterplots of all species show the effects of fuel variability on the flame compositional structures. The behaviours of major combustion products and key radicals species indicate the effects of CO concentration on the 2/CO syngas combustion. In particular, high concentration of CO tends to induce local extinction in the 2/CO flames in which critical chemical reactions of the fuel mixture such as CO + OH become important. The unsteady fluctuations of species profiles in the wall jet region characterise the complexity of the distributions of compositional structures in the near-wall region with respect to the effects of CO concentration on the combustion of hydrogen-enriched fuels.     

Hydrogen-enriched non-premixed jet flames: Analysis of the flame surface,flame normal,flame index and Wobbe index

A non-premixed impinging jet flame is studied using three-dimensional direct numerical simulation with detailed chemical kinetics in order to investigate the influence of fuel variability on flame surface, flame normal, flame index and Wobbe index for hydrogen-enriched combustion. Analyses indicate that the fuel composition greatly influences the H₂/CO syngas combustion, not only on the important local stoichiometric iso-mixture fraction surface distribution but also on the vortical structures in the flow field. As a result of CO addition to hydrogen-rich combustion, changes of the reaction zone in the flammable layer, shift of peak flame surface density distribution, shift of non-premixed regions, formation of widely populated scalar dissipation distribution rate with respect to tangential strain and reduction of global heat release are all found to appear. In particular, the CO addition induces a micromixing process which appears to be an important factor for the modelling investigation of turbulence/chemistry interaction especially for combustion modelling of H₂-rich syngas fuels.     

A computational study of combustion and extinction of opposed-jet syngas diffusion flames

This paper reports a numerical study on the combustion and extinction characteristics of opposed-jet syngas diffusion flames. A model of one-dimensional counterflow syngas diffusion flames was constructed with constant strain rate formulations, which used detailed chemical kinetics and thermal and transport properties with flame radiation calculated by statistic narrowband radiation model. Detailed flame structures, species production rates and net reaction rates of key chemical reaction steps were analyzed. The effects of syngas compositions, dilution gases and pressures on the flame structures and extinction limits of H₂/CO synthetic mixture flames were discussed. Results indicate the flame structures and flame extinction are impacted by the compositions of syngas mixture significantly. From H₂-enriched syngas to CO-enriched syngas fuels, the dominant chain reactions are shifting from OH + H₂→H + H₂O for H₂O production to OH + CO→H + CO₂ for CO₂ production through the key chain-branching reaction of H + O₂→O + OH. Flame temperature increases with increasing hydrogen content and pressure, but the flame thickness is decreased with pressure. Besides, the study of the dilution effects from CO₂, N₂, and H₂O, showed the maximum flame temperature is decreased the most with CO₂ as the dilution gas, while CO-enriched syngas flames with H₂O dilution has highest maximum flame temperature when extinction occurs due to the competitions of chemical effect and radiation effect. Finally, extinction limits were obtained with minimum hydrogen percentage as the index at different pressures, which provides a fundamental understanding of syngas combustion and applications.     

Numerical investigation of diluent influence on flame extinction limits and emission characteristic of lean-premixed H2-CO (syngas) flames

In recent years, research efforts have been channeled to explore the use of environmentally-friendly clean fuel in lean-premixed combustion so that it is vital to understand fundamental knowledge of combustion and emissions characteristics for an advanced gas turbine combustor design. The current study investigates the extinction limits and emission formations of dry syngas (50% H₂-50% CO), moist syngas (40% H₂-40% CO-20% H₂O), and impure syngas containing 5% CH₄. A counterflow flame configuration was numerically investigated to understand extinction and emission characteristics at the lean-premixed combustion condition by varying dilution levels (N₂, CO₂ and H₂O) at different pressures and syngas compositions. By increasing dilution and varying syngas composition and maintaining a constant strain rate in the flame, numerical simulation showed among diluents considered: CO₂ diluted flame has the same extinction limit in moist syngas as in dry syngas but a higher extinction temperature; H₂O presence in the fuel mixture decreases the extinction limit of N₂ diluted flame but still increases the flame extinction temperature; impure syngas with CH₄ extends the flame extinction limit but has no effect on flame temperature in CO₂ diluted flame; for diluted moist syngas, extinction limit is increased at higher pressure with the larger extinction temperature; for different compositions of syngas, higher CO concentration leads to higher NO emission. This study enables to provide insight into reaction mechanisms involved in flame extinction and emission through the addition of diluents at ambient and high pressure.     

NO formation of opposed-jet syngas diffusion flames: Strain rate and dilution effects

The NO formation characteristics and reaction pathways of opposed-jet H₂/CO syngas diffusion flames were analyzed with a revised OPPDIF program which coupled a narrowband radiation model with detailed chemical kinetics in this work. The effects of strain rates ranging from 0.1 to 1000 s^?1 and diluents including CO₂, H₂O and N₂ on NO production rates were investigated for three typical syngas compositions. The numerical results demonstrated that NO is produced primary through NNH-intermediate route and thermal route at high strain rates, where the reaction of NH + O = NO + H (R51) also become more active. Near the strain rate of 10 s^?1, the flame temperature is the highest and thermal route is the dominant NO formation route, but NO would be consumed by reburn route where NO is converted to NH through HNO, especially for H₂-rich syngas. At low strain rates, radiative heat loss results in a lower flame temperature and further reduce NO formation, while the reaction of N + CO₂ = NO + CO (R140) become more important, especially for CO-rich syngas. With the diluents, NO production rates decreased with increasing dilution percentages. When the flame temperature is very high as the thermal route is dominant near strain rate of 10 s^?1, CO₂ dilution makes flame temperature and NO production rate the lowest. Toward both lower and higher strain rates, adding H₂O is more effective in reducing NO because R140 and NNH-intermediate route are suppressed the most by H₂O dilution respectively.     

Influences of different diluents on NO emission characteristics of syngas opposed-flow flame

This paper used the opposed-flow flame model and GRI 3.0 mechanism to investigate NO emission characteristics of H₂-rich and H₂-lean syngas under diffusion and premixed conditions, respectively, and analyzed influences of adding H₂O, CO₂ and N₂ on NO formation from the standpoint of thermodynamics and reaction kinetics. For diffusion flames, thermal route is the dominant pathway to produce NO, and adding N₂, H₂O and CO₂ shows a decreasing manner in lowering NO emission. The phenomenon above is more obvious for H₂-rich syngas because it has higher flame temperature. For premixed flames, adding CO₂ causes higher NO concentration than adding H₂O, because adding CO₂ produces more O radical, which promotes formation of NO through NNH + O = NH + NO, NH + O = NO + H and reversed N + NO = N₂ + O. And in burnout gas, thermal route is the dominant way for NO formation. Under this paper's conditions, adding N₂ increases the formation source of NO as well as decreases the flame temperature, and it reduces the NO formation as a whole. In addition, for H₂-lean syngas and H₂-rich syngas with CO₂ as the diluent, N + CO₂ = NO + CO plays as an important role in thermal route of NO formation.     

Effects of Lewis number and preferential diffusion on flame characteristics in 80%H2/20%CO syngas counterflow diffusion flames diluted with He and Ar

Numerical study is conducted to grasp flame characteristics in H₂/CO syngas counterflow diffusion flames diluted with He and Ar. An effective fuel Lewis number, applicable to premixed burning regime and even to moderately stretched diffusion flames, is suggested through the comparison among fuel Lewis number, effective Lewis number, and effective fuel Lewis number. Flame characteristics with and without the suppression of the diffusivities of H, H₂, and He are compared in order to clarify the important role of preferential diffusion effects through them. It is found that the scarcity of H and He in reaction zone increases flame temperature whereas that of H₂ deteriorates flame temperature. Impact of preferential diffusion of H, H₂, and He in flame characteristics is also addressed to reaction pathways for the purpose of displaying chemical effects.     

Stability characteristics of non-premixed turbulent jet flames of hydrogen and syngas blends with coaxial air

The stability characteristics of attached hydrogen (H₂) and syngas (H₂/CO) turbulent jet flames with coaxial air were studied experimentally. The flame stability was investigated by varying the fuel and air stream velocities. Effects of the coaxial nozzle diameter, fuel nozzle lip thickness and syngas fuel composition are addressed in detail. The detachment stability limit of the syngas single jet flame was found to decrease with increasing amount of carbon monoxide in the fuel. For jet flames with coaxial air, the critical coaxial air velocity leading to flame detachment first increases with increasing fuel jet velocity and subsequently decreases. This non-monotonic trend appears for all syngas composition herein investigated (50/50 → 100/0% H₂/CO). OH^∗ chemiluminescence imaging was performed to qualitatively identify the mechanisms responsible for the flame detachment. For all fuel compositions, local extinction close to the burner rim is observed at lower fuel velocities (ascending stability limit), while local flame extinction downstream of the burner rim is observed at higher fuel velocities (descending stability limit). Extrema of the non-monotonic trends appear to be identical when the nozzle fuel velocity is normalized by the critical fuel velocity obtained for the single jet cases.     

Flame front structure of turbulent premixed flames of syngas oxyfuel mixtures

In order to investigate oxyfuel combustion characteristics of typical composition of coal gasification syngas connected to CCS systems. Instantaneous flame front structure of turbulent premixed flames of CO/H₂/O₂/CO₂ mixtures which represent syngas oxyfuel combustion was quantitatively studied comparing with CH₄/air and syngas/air flames by using a nozzle-type Bunsen burner. Hot-wire anemometer and OH-PLIF were used to measure the turbulent flow and detect the instantaneous flame front structure, respectively. Image processing and statistical analyzing were performed using the Matlab Software. Flame surface density, mean progress variable, local curvature radius, mean flame volume, and flame thickness, were obtained. Results show that turbulent premixed flames of syngas possess wrinkled flame front structure which is a general feature of turbulent premixed flames. Flame surface density for the CO/H₂/O₂/CO₂ flame is much larger than that of CO/H₂/O₂/air and CH₄/air flames. This is mainly caused by the smaller flame intrinsic instability scale, which would lead to smaller scales and less flame passivity response to turbulence presented by Markstain length, which reduce the local flame stretch against turbulence vortex. Peak value of Possibility Density Function (PDF) distribution of local curvature radius, R, for CO/H₂/O₂/CO₂ flames is larger than those of CO/H₂/O₂/air and CH₄/air flames at both positive and negative side and the corresponding R of absolute peak PDF is the smallest. This demonstrates that the most frequent scale is the smallest for CO/H₂/O₂/CO₂ flames. Mean flame volume of CO/H₂/O₂/CO₂ flame is smaller than that of CH₄/air flame even smaller than that of CO/H₂/O₂/air flame. This would be due to the lower flame height and smaller flame wrinkles.     

An experimental study of syngas combustion in a bidirectional swirling flow

The paper reports on the results of an experimental study of methane and syngas combustion as well as their co-firing in a bidirectional swirling flow. The results confirmed that the bidirectional flow structure provides a significant decrease in the lean blow-off equivalence ratio as well as that of emissions of main pollutants. The combustion intensification becomes more evident when using syngas is as fuel. The composition of the used syngas is as follows (by volume): H₂ - 29.42%; CO - 14.32%; CH₄ - 3.8%; N₂ - 49.11%; H₂O - 3.35%. In this case, the lean blow-off is achieved at ? < 0.1, NOx emission is halved, while CxHy and CO emissions become 20 times less compared to pure methane combustion. However, according to experimental results, the co-combustion of syngas (volume fraction V_syn = 15%) and methane is the most appropriate fuel utilization mode. It provides blow-off and emission properties similar to those for combustion of pure syngas, whereas energy consumption for its production is much lower. Moreover, unlike hydrocarbon fuel combustion, that of syngas in a bidirectional swirling flow is characterized by the presence of density stratification. This is accompanied by the flame formation at significantly different locations in the combustion chamber at lean and “ultra-lean” modes of operation. Hydrogen combustion most likely to occur in the core region at near-blow-off modes ? < 0.1, whereas normal ‘operating modes in the range 0.2 = ? ≤ 0.4 result in the formation of a conical flame surface where CH₄ and CO combustion occurs. These new results with respect to the flame structure as well as blow-off and emission properties make it possible to consider bidirectional vortex combustors for application in modern gas turbine power plants in order to meet the strict environmental and energy requirements.     

Radiation intensity imaging measurements of methane and dimethyl ether turbulent nonpremixed and partially premixed jet flames

Quantitative time-dependent images of the infrared radiation intensity from methane and dimethyl ether (DME) turbulent nonpremixed and partially premixed jet flames are measured and discussed in this work. The fuel compositions (CH₄/H₂/N₂, C₂H₆O/H₂/N₂, CH₄/air, and C₂H₆O/air) and Reynolds numbers (15,200–46,250) for the flames were selected following the guidelines of the International Workshop on Measurement and Computation of Turbulent Nonpremixed Flames (TNF Workshop). The images of the radiation intensity are acquired using a calibrated high speed infrared camera and three band-pass filters. The band-pass filters enable measurements of radiation from water vapor and carbon dioxide over the entire flame length and beyond. The images reveal localized regions of high and low intensity characteristic of turbulent flames. The peak mean radiation intensity is approximately 15% larger for the DME nonpremixed flames and 30% larger for the DME partially premixed flames in comparison to the corresponding methane flames. The trends are explained by a combination of higher temperatures and longer stoichiometric flame lengths for the DME flames. The longer flame lengths are attributed to the higher density of the DME fuel mixtures based on existing flame length scaling relationships. The longer flame lengths result in larger volumes of high temperature gas and correspondingly higher path-integrated radiation intensities near and downstream of the stoichiometric flame length. The radiation intensity measurements acquired with the infrared camera agree with existing spectroscopy measurements demonstrating the quantitative nature of the present imaging technique. The images provide new benchmark data of turbulent nonpremixed and partially premixed jet flames. The images can be compared with results of large eddy simulations rendered in the form of quantitative images of the infrared radiation intensity. Such comparisons are expected to support the evaluation of models used in turbulent combustion and radiation simulations.     

Measurement of the instantaneous flame front structure of syngas turbulent premixed flames at high pressure

Instantaneous flame front structure of syngas turbulent premixed flames including the local radius of curvature, the characteristic radius of curvature, the fractal inner cutoff scale and the local flame angle were derived from the experimental OH-PLIF images. The CO/H₂/CO₂/air flames as a model of syngas/air combustion were investigated at pressure of 0.5 MPa and compared to that of CH₄/air flames. The convex and concave structures of the flame front were detected and statistical analysis including the PDF and ADF of the local radius of curvature and local flame angle were conducted. Results show that the flame front of turbulent premixed flames at high pressure is a wrinkled flame front with small scale convex and concave structures superimposed with large scale flame branches. The convex structures are much more frequent than the concave ones on flame front which reflects a general characteristic of the turbulent premixed flames at high pressure. The syngas flames possess much wrinkled flame front with much smaller fine cusps structure compared to that of CH₄/air flames and the main difference is on the convex structure. The effect of turbulence on the general wrinkled scale of flame front is much weaker than that of the smallest wrinkled scale. The general wrinkled scale is mainly dominated by the turbulence vortex scale, while, the smallest wrinkled scale is strongly affected by the flame intrinsic instability. The effect of flame intrinsic instability on flame front of turbulent premixed flame is mainly on the formation of a large number of convex structure propagating to the unburned reactants and enlarge the effective contact surface between flame front and unburned reactants.     

Turbulent burning velocity of stoichiometric syngas flames with different hydrogen volumetric fractions upon constant-volume method with multi-zone model

Syngas has been widely concerned and tested in various thermo-power devices as one promising alternative fuel. However, little is known about the turbulent combustion characteristics, especially on outwardly propagating turbulent syngas/air premixed flames. In this paper, the outwardly propagating turbulent syngas/air premixed flames were experimentally investigated in a constant-volume fan-stirred vessel. Tests were conducted on stoichiometric syngas with different hydrogen volumetric fractions (X_H2, 10%–90%) in the ambience with different initial turbulence intensity (u'_rms, 0.100 m/s~1.309 m/s). Turbulent burning velocity was taken as the major topic to be studied upon the multi-zone model in constant-volume propagating flame method. The influences of initial turbulent intensity and hydrogen volumetric fraction on the turbulent flame speed were analysed and discussed. An explicit correlation of turbulent flame speed was obtained from the experimental results.     

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.