Lean Premixed Prevaporized Combustion Research Articles

Numerical Analysis of Flame Shape Impact on the Performance of Fuel Staging in a Lean-Burn Aeronautical Burner

Abstract The BIMER combustor is a lab-scale burner investigating fuel staging techniques as a stabilization strategy for lean premixed prevaporized combustion for aeronautical applications. Two stages compose its injection system: the pilot and the multipoint stages. The staging factor is defined as the ratio of fuel mass flowrate injected through the pilot stage over the total one. As three flame shapes were found experimentally, Large-Eddy Simulations are performed in this study to assess the impact of the flame shape on the combustion regime and stability of the burner. Two operating conditions were explored experimentally (pilot-only and multipoint-dominated) to validate the simulations and compare the three flames. An additional multipoint-only condition is also investigated for the V flame. The combustion regimes (premixed and non-premixed) and noise signatures (as a function of fuel staging) were compared to check whether these flames could benefit from the staging strategy. The M and Tulip flame combustion regimes are little affected by fuel staging, remaining mostly premixed and non-premixed, respectively, regardless of fuel staging. In opposition, the V flame changes from being mostly non-premixed to completely premixed when the injection is changed from pilot-only to multipoint-only. For the same staging factor values, the V flame also emits less noise compared to the other two flame shapes. These results show that the V flame shape is the only one that allows this burner to benefit from an efficient fuel staging strategy.

DNS analysis of turbulence modulation by lean premixed prevaporized spray flames in a model combustor

Turbulence modulation by lean premixed prevaporized (LPP) spray flames, which involve droplet motion, evaporation and gaseous reaction, is complicated and essential to organizing clean and efficient combustion. Direct numerical simulations of LPP combustion in a model swirling combustor under high pressure of 20 bar are performed. The gaseous flow is solved in the low-Mach-number limit, and the droplets are tracked as two-way coupled Lagrangian particles. The corrected infinite thermal conductivity model is adopted to describe droplet evaporation, and a reduced two-step kerosene/air chemistry mechanism is used to present combustion. Four cases, i.e., a non-reacting gaseous flow, a non-reacting spray flow and two reacting spray flows with different droplet sizes, are conducted to cover key features of LPP flame on turbulence modulation. The results show that the spray combustion significantly depresses the mean axial velocity on the centerline in the upstream, indicating an enhancement of the inner recirculation zone. The influence of droplets on the mean and fluctuating velocities is generally negligible except on the azimuthal modulation, while combustion can increase the velocities, which is more evident in downstream due to the pressure effect. In reacting cases, the turbulent kinetic energy (TKE) spectra in the shear layers reduce at high wavenumbers, reflecting the combustion-induced dissipation at small scales (below the laminar flame thickness scale). Besides, droplet evaporation can introduce energy at small scales while this modulation is balanced by combustion. Moreover, TKE budget analysis indicates that spray combustion mainly depresses the TKE and redistributes mean shear along the radial direction. Heat release increases the local fluid viscosity, depresses local turbulent transport, and increases viscous dissipation. Finally, the vortex stretching analysis shows that LPP combustion enhances the alignment with the intermediate strain rate component.

MID-IR laser absorption spectroscopy of 1- and 2-butanol in a shock tube facility

E-fuels are CO2-neutral fuels generated using renewable fuels such as wind and solar energy, where the carbon is taken out of the atmosphere or from biomass. One of the suitable e-fuel classes are alcohols with a low number of carbon atoms. Obtaining the low pollutant emissions on combusting liquid fuels such as fuel oil and kerosene, e-fuels with lean, premixed, pre-vaporized (LPP) concept plays a pivotal role. So, in this framework, the present work focuses on the combustion properties in the low pressure and high-temperature regime of 1- and 2-butanol isomers to evaluate their potential as future sustainable aviation fuels. The study investigates the fuel-lean conditions of 1- and 2-butanol in the fuel/oxygen equivalence ratios of 0.25, 0.5, and 0.9 relevant to the LPP (Yan et al. 2015) combustion concept for its applications in aviation. The flame chemistry of butanol isomers has been widely investigated; however, more investigations on ignition chemistry are needed. For this, tunable diode laser absorption spectroscopy is utilized to obtain the time-resolved CO formation history, ignition delay time (IDT), and progress in the butanol consumption by applying the central wavelength of 2059.91 cm−1 and 2948.27 cm−1, respectively. The measurements were performed in the temperature range of 1150–1500 K near 1.5 and 3 bar. The experimentally obtained IDT were validated with several recent reaction mechanisms available in the literature. The correlation between measured IDT, CO formation, and butanol consumption data was captured by the simulations satisfactorily. However, the CO formation from the simulation shows disagreement with the experimentally obtained signal. In addition, discrepancies in the absolute CO were observed between simulation and experiment. Moreover, a sharp drop was observed for the butanol consumption histories predominantly at ϕ= 0.9 in both 1-and 2-butanol, which could not be predicted from the available mechanisms. Furthermore, by updating the rate constants of several key reactions near the sharp fall region, a better prediction from the mechanism was seen. The time-resolved CO profile and butanol consumption history, along with the absorption cross-section data for 1- and 2-butanol isomers, are reported for the first time in this paper.

Kinetic Modeling Study on the Combustion Characterization of Synthetic C3 and C4 Alcohols for Lean Premixed Prevaporized Combustion

To reach sustainable aviation, one approach is to use electro-fuels (e-fuels) within the gas turbine engines. E-fuels are CO2-neutral synthetic fuels which are produced employing electrical energy generated from renewable resources, where the carbon is taken out of the atmosphere or from biomass. Our approach is, to find e-fuels, which can be utilized in the lean premixed prevaporized (LPP) combustion, where most of the non-CO2 emissions are prevented. One of the suitable e-fuel classes is alcohols with a low number of carbons. In this work, the autoignition properties of propanol isomers and butanol isomers as e-fuels were investigated in a high-pressure shock tube (HPST) at temperatures from 1200 to 1500 K, the pressure of 10 bar, and lean fuel-air conditions. Additional investigations on the low-temperature oxidation and flame speed of C3 and C4 alcohols from the literature were employed to develop a comprehensive mechanism for the prediction of ignition delay time (IDT) and laminar burning velocity (LBV) of the above-mentioned fuels. A numerical model based on newly developed chemical kinetics was applied to further study the IDT and LBV of fuels in comparison to the Jet-A surrogate at the engine-related conditions along with the emissions prediction of the model at lean fuel-air conditions.

Combustion and emission characteristics of Jojoba biodiesel-jet A1 mixtures applying a lean premixed pre-vaporized combustion techniques: An experimental investigation

Abstract The raw Jojoba oil is utilized to produce biodiesel via a transesterification process, which is optimized using smoke point, yield, and viscosity of produced biodiesel, as well as the final product, is characterized utilizing GC-MS and FTIR. Then, the combustion and emission characteristics of Jojoba oil biodiesel-Jet-A1 blends are performed utilizing a lean premixed pre-vaporized combustion (LPP) approach. The JME with two blending ratios of 10% and 20% by volume and jet fuel of 90% and 80% by volume, as well as the pure jet fuel, are burned in an LPP combustor at two different equivalence ratios of 0.87 and 0.95 to investigate the suitability of using the JME-jet A1 fuel blends as an alternative energy resource. The LPP combustor is designed precisely regarding a comprehensive survey of the main parameters affecting on it, and its combustion results show that it has an acceptable and stable flame. The results indicate that the NOx emission decreases with enlarging the volume fraction of JME, while the CO and UHC formation increase. The flame temperature distributions are similar for the different tested fuels. It can be deduced that Jojoba biodiesel can be used up to 20% by volume as an alternative fuel with jet fuel in a commercial application.

Experimental study on NOx emission correlation of fuel staged combustion in a LPP combustor at high pressure based on NO-chemiluminescence

Experimental investigations on NOx emissions of a single-cup, Lean Premixed Prevaporized (LPP), module combustor were carried out at elevated inlet temperature and pressure up to 810 K and 2.0 MPa, close to the real operating conditions of aero-engine combustors. This LPP combustor adopts centrally staged fuel injections which could produce separated stratified swirling spray flame. In the NOx emissions measurements, the ranges of dome equivalence ratio and fuel stage ratio were from 0.55 to 0.58 and 8% to 24%, respectively. The optical diagnosis on separated stratified swirling spray flame were carried out with fuel stage ratio changing from 15% to 30%. Therefore, NO* and OH* chemiluminescence images were obtained. The results show that NOx emissions increase with the increase of the fuel stage ratio. And from the chemiluminescence images, the main flame and pilot flame are found weakly coupled. The pilot flame plays a significant role in NOx emission production because of its higher adiabatic flame temperature. Based on the results of chemiluminescence optical tests, a new NOx emission prediction model is proposed based on the Lefebvre’s single flame model. The estimate of local equivalence ratio of the pilot stage’s non-premixed flame is modified considering the characteristics of spray combustion, and a “PLUS” emission prediction model suitable for separated stratified swirling spray flame is obtained. Compared to the experimental data, the “PLUS” model exhibits a good prediction in a range of ±13% of deviation.

Inlet temperature driven supercritical bifurcation of combustion instabilities in a lean premixed prevaporized combustor

The present article reports experimental observation and analyses of a supercritical bifurcation of combustion instabilities triggered by the air inlet temperature (Ta). The studies are performed with a pressurised kerosene fuelled Lean Premixed Prevaporized (LPP) combustor operated under elevated temperature. Unlike some previous studies, starting from an unstable condition of the system, the amplitude of combustion instabilities suddenly decrease when Ta exceeds a critical value of Ta = 570 K. When the temperature is lowered back the system returns to being unstable without featuring any hysteresis behaviour, as expected in case of a supercritical bifurcation. The unstable flames feature a periodic axial motion of lift-off and re-ignition, characterized as Helmholtz mode. The phase difference between chemiluminescence and pressure signals is found to increase with Ta, exceeding 90 degrees (out of phase) for temperatures higher than 570 K. A low order network framework is conducted, illustrating that when Ta is increased a stability shift of this mode is predicted at Ta near 570 K, in good agreement with the experimental observations. The impact of Ta on the spray characteristics is also examined, finding that higher Ta promotes fuel evaporation and reduces equivalence ratio fluctuation at the exit of the swirler.

Combustion Oscillation Characteristics and Flame Structures in a Lean Premixed Prevaporized Combustor

The combustion oscillation characteristics in the lean premixed prevaporized (LPP) combustor at different equivalence ratios and inlet velocities of the combustor were experimentally investigated. Acoustic modal analysis was carried out to identify the acoustic eigenmodes in the LPP combustor. The flame structures under different operating conditions were investigated. The evolution laws of flame structures, coordinates and velocities of the flame centers, and heat release rates throughout a combustion oscillation cycle were investigated by phase-locked OH planar laser-induced fluorescence (PLIF). The result shows that there is a periodical process of flame roll-up for the flame close to the LPP combustor axis and a periodical process of separation and consolidation for the flame far from the LPP combustor axis. The spatial distribution of the normalized Rayleigh index in the LPP combustor was calculated to determine the driving zones of the combustion oscillation. The mechanism of combustion oscillation ...

Fuel spray characteristics investigation in LPP combustor

Purpose This paper aims to get an in-depth understanding of the fuel spray characteristics to further improve the emission performance of a lean premixed prevaporized (LPP) combustor with staged lean combustion. Design/methodology/approach In this paper, the fuel spray characteristics in the LPP combustor are experimentally studied by using particle image velocimetry (PIV), and raw data are processed by image-processing technologies for different inlet conditions. The effects of the fuel allocation and pilot atomizer position on fuel spray characteristics are investigated. Findings Experiment results show that when only the pilot atomizer is operated, the fuel spray characteristics is worsened by increasing fuel flow rate. The fuel spray fields generated by the pilot atomizer are better at the throat than that at the pilot swirler outlet; when the pilot atomizer and primary injector are operated at the same time with the same inlet fuel air ratio, the spray characteristics are improved by increasing the primary fuel flow rate and decreasing the pilot fuel flow rate. Meanwhile, fuel spray fields generated by the pilot atomizer are better at the throat than that at the pilot swirler outlet. Practical implications The present results are useful for further development of the LPP combustor. Originality/value An LPP combustor with staged lean combustion technology was proposed; to obtain fuel spray characteristics, image-processing program was compiled; the fuel spray characteristics in the LPP combustor were investigated, especially the effects of the fuel allocation and pilot atomizer position.

A Numerical Study of Spray Injected in a Gas Turbine Lean Pre-Mixed Pre-Vaporized Combustor

AbstractThe authors have performed a numerical study to investigate the spray evolution in a modern gas turbine combustor of the Lean Pre-Mixed Pre-vaporized type. The CFD tool is able to simulate the injection conditions, by isolating and studying some specific phenomena. The calculations have been performed by using a 3-D fluid dynamic code, the FLUENT flow solver, by choosing the injection models on the basis of a comparative analysis with some experimental data, in terms of droplet diameters, obtained by PDA technique.In a first phase of the investigation, the numerical simulation refers to non-evaporating flow conditions, in order to validate the estimation of the fundamental spray parameters. Next, the calculations employ boundary conditions close to those occurring in the actual combustor operation, in order to predict the fuel vapour distribution throughout the premixing chamber. The results obtained allow the authors to perform combustion simulation in the whole domain.

Experimental study of flow dynamics and fuel spray characteristics in Lean Premixed Prevaporized Combustor

Further improving the emission performance of a Lean Premixed Prevaporized (LPP) combustor is a hot topic for gas turbine research. An in-depth understanding of the combustion characteristics is therefore highly desirable. In this paper, the flow fields and fuel spay characteristics in a LPP combustor are experimentally studied by using Particle Image Velocimetry (PIV). The effects of the fuel allocation and pilot atomizer position on fuel spray characteristics are investigated. Experimental results show that: (1) A Primary Recirculation Zone (PRZ), Corner Recirculation Zone (CRZ) and Lip Recirculation Zone (LRZ) are presented in the flow field in a LPP combustor; (2) The width of the primary recirculation zone initially increases along axial direction from the combustor inlet, and starts to decrease after certain distance; (3) When only the pilot atomizer is operated, the fuel spray characteristics is worsened with the increase of fuel flow rate. Locating the pilot atomizer at the throat results is a better fuel spray distribution than locating it at the outlet of the pilot swirler. The present results are useful for future development of the LPP combustor.

Numerical study of turbulent structures for lean premixed prevaporized combustion

In this paper we demonstrate the advantages of the LES-WALE model coupled with the PDF approach to resolve a set of aerothermochemistry equations for turbulent lean premixed prevaporized combustion. The main issue is the modeling of the closure in the turbulent combustion equations. So, combustion problems involve a strong coupling between dynamic and scalar parameters. The validation is based on comparisons of three parameters: mean longitudinal velocity, fluctuation of longitudinal velocity, and length of recirculation zones. In line with what was observed by an experimental reference study, the simulation succeeds to detect the flame zone and to model the flow morphology for different equivalence ratios and inlet mass flow rates.

1110 ジェットエンジン用エアーブラスト式噴射弁の微粒化用空気供給路の形状が噴霧特性に及ぼす影響

Emission of nitrogen oxides (NOx) caused by exhaust gas from airplane is computed approximately 60% at high-altitude. Lean premixed-prevaporized combustion is given for one of methods of NOx reduction in jet engines. Improvement of spray characteristics before combustion is important for fuel injection of jet engine, which is leaded to redaction of exhaust gas emission at high-load conditions and high-dispersion of fuel. However, air-blast atomizer has the following characteristics that velocity of atomizing air decreases with an increase in rapidly large droplets of spray. Therefore, it is required that uniform and small droplets are obtained independent of atomizing air flow rate. The purpose of this study is that uniform and small droplets are obtained under low atomizing air velocity, to improve spray characteristics and homogeneous droplets is generated at wide region of spray. It was investigated that effects of shapes of supplying passage for atomizing air of air-blast atomizer on spray characteristics. As a results, it was cleared that excellent spray characteristics, that is, large spray angle of about 140 deg. and relatively small Sauter mean diameter of about 40 μm, was obtained by using the air-blast atomizer which was designed in this study.

Characterization of the Acoustic Interactions in a Two-Stage Multi-Injection Combustor Fed With Liquid Fuel

Burners operating in lean premixed prevaporized (LPP) regimes are considered as good candidates to reduce pollutant emissions from gas turbines. Lean combustion regimes result in lower burnt gas temperatures and therefore a reduction on the NOx emissions, one of the main pollutant species. However, these burners usually show strong flame dynamics, making them prone to various stabilization problems (combustion instabilities, flashback, flame extinction). To face this issue, multi-injection staged combustion can be envisaged. Staging procedures enable fuel distribution control, while multipoint injections can lead to a fast and efficient mixing. A laboratory-scale staged multipoint combustor is developed in the present study, in the framework of LPP combustion, with an injection device close to the industrial one. Using a staging procedure between the primary pilot stage and the secondary multipoint one, droplet and velocity field distributions can be varied in the spray that is formed at the entrance of the combustion chamber. The resulting spray and flame are characterized using OH-planar laser induced fluorescence, high speed particle image velocimetry, and phase Doppler anemometry measurements. Three staging values, corresponding to three different flame stabilization processes, are analyzed, while power is kept constant. It is shown that mean values are strongly influenced by the fuel distribution and the flame position. Using adequate postprocessing, the interaction between the acoustic field and the droplet behavior is characterized. Spectral analysis reveals a strong acoustic-flame coupling leading to a low frequency oscillation of both the velocity field and the spray droplet distribution. In addition, acoustic measurements in the feeding line show that a strong oscillation of the acoustic field leads to a change in fuel injection, and hence droplet behavior.

Bifurcation analysis of the effect of hydrogen addition on the dynamic behavior of lean premixed pre-vaporized ethanol combustion

In this work, a mathematical model of fuel conversion and energy balance has been developed to study the dynamic behavior of a lean premixed pre-vaporized combustor fed with ethanol/air and ethanol–hydrogen/air mixtures. The combustor was modeled as a well stirred reactor (WSR). Results show that, for a simplified model reaction, Hopf bifurcations occur. Spontaneous oscillations have been found, suggesting that the combustion reaction plays an important role in the development of dynamic regimes. Hydrogen addition stabilizes ethanol combustion, damping the oscillations.

Impact of the equivalence ratio and the mass flow rate on turbulent lean premixed prevaporized combustion

Abstract Our contribution consists of the demonstration of the advantages of LES-WALE coupled with PDF approach including progress variable (c) in reacting flow, by using the Fluent-CFD. The confirmation is based on the comparison of three parameters: mean longitudinal velocity, intensity of longitudinal velocity and lengths of recirculations zones. In line with what was observed by the experimental reference study, the simulation succeeds to detect the flame zone of the recirculating region and shows the differences between the different cases of flows in variable equivalence ratio (Φ=0.60 and 0.75) or in variable mass flow rate (Q= 65 and 195 g/s). All cases of study considered the identical conditions from the tow supply channels of the burner. The main issue is the modeling of the closure of the turbulent combustion. In addition, the numerical simulation predicts as well as the asymmetry and the symmetry flow, respectively, for inert and reacting flows.

A multi-objective design optimization strategy as applied to pre-mixed pre-vaporized injection systems for low emission combustors

This paper presents a multi-objective optimization procedure as applied to the design of the injection system of a Lean Pre-mixed Pre-vaporized combustion chamber. The optimizer drives an Artificial Neural Network in a repeated analysis scheme in order to simultaneously reduce NOX and CO pollutant emissions. The ANN is trained with a few three-dimensional high resolution reactive viscous flow simulations, carried out with a reliable and robust CFD code. Results, obtained in a four-dimensional state space, demonstrate the validity of the overall procedure with truly moderate computational costs.

Atmospheric low swirl burner flow characterization with stereo PIV

The lean premixed prevaporized (LPP) burner concept is now used in most of the new generation gas turbines to reduce flame temperature and pollutants by operating near the lean blow-off limit. The common strategy to assure stable combustion is to resort to swirl stabilized flames in the burner. Nevertheless, the vortex breakdown phenomenon in reactive swirling flows is a very complex 3D mechanism, and its dynamics are not yet completely understood. Among the available measurement techniques to analyze such flows, stereo PIV (S-PIV) is now a reliable tool to quantify the instantaneous three velocity components in a plane (2D–3C). It is used in this paper to explore the reactive flow of a small scale, open to atmosphere, LPP burner (50 kW). The burner is designed to produce two distinct topologies (1) that of a conventional high swirl burner and (2) that of a low swirl burner. In addition, the burner produces a lifted flame that allows a good optical access to the whole recirculation zone in both topologies. The flow is studied over a wide range of swirl and Reynolds numbers at different equivalence ratios. Flow statistics are presented for 1,000 S-PIV snapshots at each configuration. In both reactive and cold nonreactive flow, stability diagrams define the domains of the low and high swirl topologies. Due to the relatively simple conception of the physical burner, this information can be easily used for the validation of CFD computations of the burner flow global structure. Near field pressure measurements reveal the presence of peaks in the power spectra, which suggests the presence of periodical coherent features for almost all configurations. Algorithms have been developed to identify and track large periodic traveling coherent structures from the statistically independent S-PIV realizations. Flow temporal evolution is reconstructed with a POD-based method, providing an additional tool for the understanding of flow topologies and numerical codes validation.

A Time-Domain Network Model for Nonlinear Thermoacoustic Oscillations

Lean premixed prevaporized (LPP) combustion can reduce NOx emissions from gas turbines but often leads to combustion instability. Acoustic waves produce fluctuations in heat release, for instance, by perturbing the fuel-air ratio. These heat fluctuations will in turn generate more acoustic waves and in some situations linear oscillations grow into large-amplitude self-sustained oscillations. The resulting limit cycles can cause structural damage. Thermoacoustic oscillations will have a low amplitude initially. Thus linear models can describe the initial growth and hence give stability predictions. An unstable linear mode will grow in amplitude until nonlinear effects become sufficiently important to achieve a limit cycle. While the frequency of the linear mode can often provide a good approximation to that of the resulting limit cycle, linear theories give no prediction of its resulting amplitude. In previous work, we developed a low-order frequency-domain method to model thermoacoustic limit cycles in LPP combustors. This was based on a “describing-function” approach and is only applicable when there is a dominant mode and the main nonlinearity is in the combustion response to flow perturbations. In this paper that method is extended into the time domain. The main advantage of the time-domain approach is that limit-cycle stability, the influence of harmonics, and the interaction between different modes can be simulated. In LPP combustion, fluctuations in the inlet fuel-air ratio have been shown to be the dominant cause of unsteady combustion: These occur because velocity perturbations in the premix ducts cause a time-varying fuel-air ratio, which then convects downstream. If the velocity perturbation becomes comparable to the mean flow, there will be an amplitude-dependent effect on the equivalence ratio fluctuations entering the combustor and hence on the rate of heat release. Since the Mach number is low, the velocity perturbation can be comparable to the mean flow, with even reverse flow occurring, while the disturbances are still acoustically linear in that the pressure perturbation is still much smaller than the mean. Hence while the combustion response to flow velocity and equivalence ratio fluctuations must be modeled nonlinearly, the flow perturbations generated as a result of the unsteady combustion can be treated as linear. In developing a time-domain network model for nonlinear thermoacoustic oscillations an initial frequency-domain calculation is performed. The linear network model, LOTAN, is used to categorize the combustor geometry by finding the transfer function for the response of flow perturbations (at the fuel injectors, say) to heat-release oscillations. This transfer function is then converted into the time domain through an inverse Fourier transform to obtain Green’s function, which thus relates unsteady flow to heat release at previous times. By combining this with a nonlinear flame model (relating heat release to unsteady flow at previous times) a complete time-domain solution can be found by stepping forward in time. If an unstable mode is present, its amplitude will initially grow exponentially (in accordance with linear theory) until saturation effects in the flame model become significant, and eventually a stable limit cycle will be attained. The time-domain approach enables determination of the limit cycle. In addition, the influence of harmonics and the interaction and exchange of energy between different modes can be simulated. These effects are investigated for longitudinal and circumferential instabilities in an example combustor system and the results are compared with frequency-domain limit-cycle predictions.

Emissions and wall temperatures for lean prevaporized premixed gas turbine combustor

Experimental studies are carried out for investigating emission and wall temperature for traditional gas turbine combustor converted to lean premixed prevaporized (LPP) combustor. Vortex chamber, air preheating system, flat flame burner and inlet temperature control system are designed. Vortex chamber was maintained at the main air inlet port for controlling secondary air flow rate and wall temperature. Kerosene/air mixture temperature at exit from burner and entering combustion chamber was kept constant at 650 K for all runs. Special considerations were given for measuring NO X , UHC, CO, local A/F ratio, flame temperature, exhaust gases temperature and wall temperature. For swirl and non swirl cases, secondary air ratio and primary zone air/fuel ratio were varied. The different operating parameters affecting flame temperature through it is affecting on local A/F ratio which is the main parameter for controlling flame temperature, emissions and walls temperatures. Flat flame burner and vortex chamber are useful tools for reducing emission and controlling walls temperatures. The inner liner wall temperatures are more affected by primary zone equivalence ratio while the outer liner wall temperatures are more affected by secondary air flow rate. Semi empirical correlations for NO X , UHC and CO concentrations, exhaust gases temperature and maximum inner liner wall temperature are carried out. Good agreement between the measured and the calculated results are obtained. The present results are useful for further development of the traditional gas turbine combustor converted to LPP combustor.