Combustor Wall Temperature Research Articles

Effects of combustor wall temperature on the outer recirculation zone combustion modes transition in lean premixed DME/air swirling flames

In this study, the effects of wall thermal boundary conditions on the outer recirculation zone (ORZ) combustion modes transition in the DME/air swirling flames were investigated using the Large Eddy Simulation (LES) and Flamelet Generated Manifold (FGM) method. The results show that the ORZ chemistry and temperature are highly sensitive to the wall thermal boundary condition. Based on the correlation between the temperature and species observed in the time-averaged numerical results, the relation between the combustion mode and temperature in the ORZ was discovered. Through temporal analysis of species and heat release rate in the ORZ, the stable Mode II and Mode IV as well as the unstable Mode III were identified. The chemical reaction pathway analysis for typical probe in the ORZ reveals that different combustion modes undergo distinct (low-temperature or high-temperature) chemical reaction pathways. Afterwards, the definition of ORZ combustion modes used in experiments was refined by utilizing the chemical reaction data from the simulations. And it was applied to identify the combustion mode across the entire computational domain. The results confirm the consistency between the combustion modes determined in experiments based on OH and CH2O and those determined in simulations using chemical reaction rates. Finally, this explains the mechanism of the flickering flame in Mode III is the competition between the low-temperature and high-temperature reaction in the ORZ. Whereas the unstable Mode III can be stabilized by changing the wall temperature to reach the stable Mode II or Mode IV.

Thermodynamic and entropy generation analyses of Telsa-valve structured meso-scale combustors fuelled with hydrogen for thermophotovoltaic applications

The present work numerically examed the effects of hydrogen volume flow rates (Qv) and equivalence ratios (Φ) on thermal performances of meso-scale combustors structured with Tesla-vale type flow channels. Four distinct Tesla-valve configurations are implemented and then subsequently compared. The reverse-flow Tesla valve with counter-flow combustor (RC) structure shows a remarkable improvement of 72.6 % to the combustor wall temperature at Qv = 100 mL/min. The diodicity (Di) of the Tesla valve is found to be increased with a higher Qv, and a lower Φ contributes to a higher Di. Besides, Di is decreased when Φ goes up, stabilizing at Φ = 0.9. The reverse-flow Tesla valve exhibits a more uniform pressure distribution and entropy production than the forward-flow Tesla valve. At Φ = 0.9, the hydrogen-to-air ratio maximized heat release, producing the highest entropy. Tesla-valve structured combustors demonstrate near complete combustion before Φ reaching 0.9, the combustion efficiency (ηcombustion) is gradually decreased after Φ getting to 1.0. The RC construction achieved maximum combustion efficiency under conditions of insufficient oxygen. This present study demonstrates the feasibility of enhancing thermal and overall performances of meso-scale combustors structured with Tesla-valve channels, and revealing the key parameters effects on the combustion characteristics in these combustors.

Effects of Fuel Flow and Airflow Swirl on Thermal Performance of a Miniature-Scale Combustor for Direct Energy Conversion Systems

Micropower generation and micropropulsion are two emerging fields where micro- and miniature-scale combustors are anticipated to play a significant role. Today, there is a growing interest in combustion-based direct energy conversion modules such as thermoelectric and thermophotovoltaic micropower generators. In this study, the effects of swirl addition to fuel flow and airflow on combustor operational envelope, flame blowout limit, combustion efficiency, exhaust gas temperature, mean outer wall temperature, emitter efficiency, and normalized temperature standard deviation of a miniature-scale (mesoscale) combustor are studied under various equivalence ratios. The findings demonstrate that swirling flows improve the flame blowout limit and operational envelope of the combustor; however, this improvement is more significant for airflow swirl. Besides simultaneous swirling flows of fuel and air result in the highest blowout limit. Additionally, it has been shown that swirl addition improves combustion efficiency and causes a significant amount of heat to be generated, which raises the temperature of the exhaust gas, the mean outer wall temperature, and the emitter efficiency. Furthermore, mean outer wall temperature and emitter efficiency have the highest values for simultaneous swirling flows of fuel and air. It is also observed that increasing the fuel flow swirl number generally lessens the normalized temperature standard deviation (NTSD) and consequently improves the combustor wall temperature uniformity, while for the airflow swirl case, a swirler with 30° vane angle for airstream has a lower NTSD than a 45° vane angle swirler. The results obtained in this study provide useful information for designing a combustion-based direct energy conversion module.

Numerical investigation of premixed methane-ammonia combustion in a mesoscale porous combustor

The present study focuses on the numerical modeling of the premixed methane-ammonia combustion in a mesoscale porous combustor. The primary objective is to reduce carbon dioxide emissions by using ammonia as a carbon-free fuel while maintaining constant the combustor wall temperature compared to pure methane. Ammonia addition in the mixture increases nitrogen oxide compared to pure methane-oxygen combustion, which is undesirable. On the other hand, porous material improves fuel and air mixing and leads to more appropriate fuel distribution which could lower the combustion temperature and as well NOx emission. So, simultaneous using ammonia and porous media in the combustion is the effective combination to reduce the consumption of hydrocarbon fuels. In the current study, porosity of porous media is changed within the range of 50 %–90 %, molar fraction of ammonia is varied from 0.1 to 0.9, and equivalence ratios ranging from 0.8 to 1. Also, to find the optimal combustion parameters, the response surface methodology has been employed. The results indicated that to achieve satisfactory conditions for methane-ammonia-oxygen combustion in contrast to the combustion of pure methane-oxygen, it is the best condition to employ a porosity of 63 %, an ammonia mole fraction of 0.9, and a stoichiometric equivalence ratio. Because of the utilization of porous media, the mean wall temperature reached to 1543 K, indicating a 3.5 % reduction compared to pure methane combustion. Simultaneously, nitrogen oxide emission drops to 2270 ppm, showcasing a 10 % reduction compared to the non-porous media ammonia-methane combustion. Additionally, the use of the 0.9 M fraction of ammonia leads to a noteworthy 75 % decrease in the mass fraction of carbon dioxide emissions compared to pure methane combustion. These findings accelerate the optimal use of carbon-free fuels such as ammonia as alternatives to hydrocarbon fuels.

Analysis of entropy generation and exergy efficiency of the methane/dimethyl ether/air premixed combustion in a micro-channel

This work presents a numerical investigation on the entropy generation and exergy efficiency in a methane/dimethyl ether/air-fueled micro combustor. To this end, a three-dimensional numerical model established is first validated by comparing its predictions with experimental data in the literature. It is, then, applied to assess the effects of the inlet velocity and blending ratio on the entropy and exergy generation. As far as the entropy generation caused by chemical reactions is concerned, there exists a reaction step that contributes most to the overall entropy. The contributing rate of such a reaction is inhibited by increasing the blending ratio. Meanwhile, for a given fuel composition, the entropy generation due to chemical reactions and heat conduction is found to exhibit a monotonic trend with the inlet velocity, whereas the entropy induced by mass diffusion shows a non-monotonic dependence. Furthermore, the exergy destruction ratio induced by the chemical reaction plays a dominant role in the total exergy generation, irrespective of inlet velocity and blending ratio. Both the exergy loss and efficiency are shown to be increasing as the inlet velocity is elevated, along with the increase in the combustor wall temperature. In general, this work identifies how blended combustion affects the entropy and exergy generation in methane/dimethyl ether combustion systems and sheds light upon the underlying mechanism.

Characterization of Biogas as an Alternative Fuel in Micro-Scale Combustion Technology

This study observes the flame characteristics of the biogas in micro/meso-scale (MSC) combustion technology, namely in a cylindrical MSC. For comparison, the fuel and combustor variations were carried out with backward-facing step size (bfs) as the flame holder in the combustor.The bfs are varied by changing the combustor's length of the inlet diameter. However, the size of the outlet diameter of the combustor is always constant to obtain a continuous combustion reaction zone. Biogas/methane (CH4), butane gas (C4H10), and a mixture of biogas-butane are used as fuel, with air as the oxidizing agent. The results showed that the type of fuel, reactant flow velocity, and equivalent ratio that occurred in the fuel variation and the bfs variation of the cylindrical msc influenced the flame characterization. Stable flame forms in the stoichiometric to rich equivalent ratio area and the medium to high reactant velocity area. The result shows that the equivalent ratio (φ) is 1.23 –1.44, the flame stability limit at the combustor ratio of 0.7, and biogas fuel has low flame stability compared to butane and the biogas-butane mixture. Moreover, the flame can be stable on butane fuel in the equivalent ratio (φ) 0.85 –1.43 and (φ) 0.86 –1.19 for the biogas-butane fuel mixture. Furthermore, when the D1/D2 increases, the flame stability of biogas tends to be wider than when the combustor ratio is 0.7, where the equivalent ratio (φ) is 0.98 –1.42. The result also shows that the flame can be stable on butane fuel in the equivalent ratio (φ) 0.71 –1.43, and for the biogas-butane fuel mixture, the flame can be stable in the equivalent ratio (φ) 0.69 –1.32. However, the best characterization of biogas combustion is formed in the variation of biogas treatment by mixing butane gas (biogas-butane). One of the methods used is called with a wider flame stability limit area. More varied flame visualization variations with a more widely distributed flame mode map, flame, and combustor wall temperature. The result shows that the combustor wall temperature of butane is around 225-250 °C, higher than the characterization of biogas combustion around 150°C, where it's without mixing butane gas for the possible test ranges.

Entropy generation and improved thermal performance investigation on a hydrogen-fuelled double-channel microcombustor with Y-shaped internal fins

To enhance the hydrogen-fueled micro-combustor's thermal performance for Thermo-photovoltaic applications, we propose and test a double-channel design featuring Y-shaped internal fins. This study investigates three key parameters in the thermal performance of a micro-combustor: the inlet velocity, the inlet equivalence ratio, and the combustor wall material. Further, we develop a new method to calculate the efficiency and exergy of the micro-combustor by considering the entropy generation and exhaust gas. It is observed that increasing the inlet velocity leads to higher mean wall temperature (MWT), standard deviation of wall temperature (SDWT), and radiation heat release rate. Increasing inlet velocity also enhances the thermodynamic second-law efficiency and exergy. The peaks of MWT and SDWT are achieved when the inlet equivalence ratio approaches unity. The inlet equivalence ratio value of unity also corresponds to the maximum radiation heat rate and improved second-law efficiency and exergy. Finally, changing the combustor wall material reveals that the silicon carbide demonstrates better thermal performance by rising MWT and the uniformity of the combustor wall temperature. Moreover, alterations to the combustor wall materials do not appear to have a significant impact on the heat loss resulting from entropy generation.

Improving the thermophotovoltaic performance of a hydrogen-fueled planar combustor with four-corner inlets via partially inserting porous medium

Micro thermophotovoltaic (TPV) generator is a potentially efficient approach to achieve microscale fuel-to-electricity conversion with high-energy–density, high-efficiency, and small-scale portability, where micro combustor provides the high-temperature continuous combustion process as well as a heat source of thermal radiation. In this study, a hydrogen-fueled planar combustor with four-corner inlets by partially inserting porous medium is proposed and investigated by a three-dimensional numerical model of porous medium combustion with detailed reaction mechanism and local thermal non-equilibrium. The combustor performance with and without partially inserting porous medium under various inlet velocities Vin and equivalence ratios ϕ are compared and analyzed to reveal the inherent strengthening mechanism. Moreover, the effects of various porous parameters on the energy conversion performance are examined: the porosity ɛ, thermal conductivity ks, and porous medium filled volume. The results demonstrate that the inserted porous medium can significantly enhance combustion efficiency, combustor wall temperature and its uniformity, and the largest increase in mean wall temperature reaches 79.7 K at Vin = 9 m/s, resulting in a 35.8 % increase in micro-TPV system efficiency. As ɛ and ks decrease, the combustor energy conversion performance increases while the temperature uniformity decreases. A moderate channel width L = 2.0 mm is good for further improving temperature uniformity and energy conversion efficiency. This study paves the way for the improvement of efficient, practical, and portable microscale generators.

Numerical analysis of relight in an annular spray-flame combustor with preheated walls

Successful relight of aero-engine combustors is subjected to certification specifications and must be ensured under various scenarios which can involve substantially different combustor wall temperatures. Unlike restart from windmilling, quick relight is likely to be performed with hot combustor walls, affecting the resulting ignition time. Few published studies exist which address wall temperature effects on ignition: for example, experiments in the annular spray-flame combustor MICCA with preheated walls have revealed that the ignition time—also referred to as light-round duration—decreases compared to cold combustor walls for otherwise same operating conditions. Numerical simulations of ignition have been carried out as well, but usually rely on approximations for the imposed wall temperature boundary condition (mostly adiabatic, iso-thermal at best) due to the lack of detailed experimental data. Therefore, the present work aims at studying the effect of preheated walls on light-round in more detail. Conjugate Heat Transfer simulations are first carried out to compute more realistic wall temperature profiles under steady reacting operating conditions in MICCA-Spray. These temperature profiles are then used in non-reacting Large-Eddy Simulations (LES) to establish preheated initial conditions. Finally, LES of light-round ignition with preheated walls are carried out. The predicted light-round duration is compared to experimental measurements, and effects on the governing flame propagation mechanisms as well as the liquid phase are examined. Differences with regard to light-round with ambient temperature walls are pointed out and the importance of an appropriate choice of boundary conditions is briefly discussed.

Effects of hydrogen-addition on the FREI dynamics of methane/oxygen mixture in meso-scale reactor

FREI (Flame with Repetitive Extinction and Ignition) is a unique flame dynamic in the micro or meso combustor due to the scale effect of the combustor. To further understand the flame dynamics of the FREI, the flame propagating process of the methane-oxygen premixed gas with hydrogen addition is visualized and analyzed experimentally in a rectangle combustor with transparent wall. The equivalence ratio regimes of different flame behaviors are obtained by varying the hydrogen addition. The effect of hydrogen addition on the flame propagation speed, the flame amplitude and the frequency of the FREI is discussed in terms of methane and hydrogen properties, as well as combustor wall temperature. The results indicate that increasing the hydrogen addition will enlarge the amplitude and decrease the frequency of the FREI. However, the effects of hydrogen addition on the flame properties in the upstream and downstream parts of the combustor vary. When the hydrogen addition is increased under the FREI condition, the temperature profile becomes more uniform upstream. Meanwhile, the flame propagates faster with higher hydrogen addition. However, due to the combined effect of wall temperature and the hydrogen property, increasing the hydrogen addition will decrease the wall temperature and the flame propagating velocity at the downstream part when the equivalence ratio is less than 1.9.

Design and Testing of a High Frequency Thermoacoustic Combustion Experiment

This paper presents a novel experiment in an atmospheric cylindrical single-jet combustor, designed to exhibit high-frequency radial thermoacoustic instabilities. The experimental configuration was designed based on an a priori set of comprehensive numerical investigations, the experiments were conducted with pressure and temperature probes, and large-eddy simulations of the final experiments were performed. The results from simulation and experiment were compared and showed reasonable agreement in the amplitude, frequency, and mode shape of the self-excited instability in the unstable operating point and no thermoacoustic oscillations in the stable operating point. Various parameters have been varied to assess their effect on thermoacoustics, including variations of mass flow rate, of equivalence ratio, and combustor wall temperatures. For the unstable cases, direct effect of pressure on density was found to drive the thermoacoustic oscillations.

Influence of hole size and number on pressure drop and energy output of the micro-cylindrical combustor inserting with an internal spiral fin with holes

Targeting at optimizing the energy output and thermal performance of the micro combustor in the application of micro-thermophotovoltaic (MTPV) systems, but the introduction of spiral fins brings higher pressure loss. Thus, a novel design of the micro combustor with the spiral fin opening is developed. The influence of inlet velocities, the hole size and hole number of the spiral fin on the pressure drop and thermal characteristic and energy characteristic are numerically investigated. It's illustrated that the spiral fin opening is conductive to decrease the pressure loss and optimize the outer wall temperature distribution, but has a negative influence on increasing the mean outer wall temperature of the micro combustor and energy output in the MTPV systems. With the increase of the hole size and hole number of the spiral fin, the pressure loss decreases and the outer wall temperature uniformity increases significantly, while the mean outer wall temperature drops and total energy output decreases. The better performance obtains when the micro combustor with spiral fin with four 0.5 mm holes.

Optimizing thermal performance and exergy efficiency in hydrogen-fueled meso-combustors by applying a bluff-body

Recognizing the importance of a bluff-body on the flow separation and its role in enhancing the fuel mixing, the effect of applying a bluff-body on the thermal performance and exergy efficiency in hydrogen-fueled meso-scale combustors are discussed using 3D numerical simulations involving a detailed kinetics mechanism. Key parameters including the bluff-body dimensionless axial location l and combustor configuration are evaluated to obtain the optimal geometry. It is found that the bottom wall mean temperature (BWMT) and its uniformity are significantly enhanced with a bluff-body applied, generally accompanied with a high average Nusselt number. This is mainly due to the fact that the bluff-body can create longitudinal vortices and disrupts the growth of the thermal boundary layer, leading to intensified heat transfer. There is a non-monotonic relationship between BWMT and l with the optimum position being l = 2/5. Further, the proposed Combustor A is involved with a higher and more uniform BWMT. Finally, the exergy efficiency in the bluff-body combustor is found to be higher compared to the conventional combustor, although the elevated pressure loss. This work demonstrates the feasibility of implementing a bluff-body to enhance the thermal performance, and some of the interesting findings can be also applied to power and propulsion systems utilizing the combustor wall temperature.

Wall Temperature Measurements in a Full-Scale Gas Turbine Combustor Test Rig With Fiber Coupled Phosphor Thermometry

Abstract Wall temperature measurements with fiber coupled online phosphor thermometry were, for the first time, successfully performed in a full-scale H-class Siemens gas turbine combustor. Online wall temperatures were obtained during high-pressure combustion tests up to 8 bar at the Siemens Clean Energy Center (CEC) test facility. Since optical access to the combustion chamber with fibers being able to provide high laser energies is extremely challenging, we developed a custom-built measurement system consisting of a water-cooled fiber optic probe and a mobile measurement container. A suitable combination of chemical binder and thermographic phosphor was identified for temperatures up to 1800 K on combustor walls coated with a thermal barrier coating (TBC). To our knowledge, these are the first measurements reported with fiber coupled online phosphor thermometry in a full-scale high-pressure gas turbine combustor. Details of the setup and the measurement procedures will be presented. The measured signals were influenced by strong background emissions probably from CO*2 chemiluminescence. Strategies for correcting background emissions and data evaluation procedures are discussed. The presented measurement technique enables the detailed study of combustor wall temperatures and using this information an optimization of the gas turbine cooling design.

Assessment of numerical radiation models on the heat transfer of an aero-engine combustion chamber

Thermal radiation is the most dominant type of heat transfer inside the combustion chamber, which can directly affect the temperature distributions at the combustor walls. This paper provides a comprehensive analysis of the effects of two radiation models on the flame and liner-walls temperatures. A combustion chamber used in the Rolls-Royce-RB-183 turbofan engine was examined in this study by integrating a solid combustor model with the numerical fluid domain. The results indicated that the implementation of radiation models shrinks the flame peak-temperature and altered temperature distribution across the liner. The Discrete Ordinates Method (DOM) estimated a 10% higher temperature at the front part of the liner compared to the non-radiation model and 15% less than the P-1 radiation method. After the dilution zone, the DOM and P-1 models estimated respectively 15% and 25% reduction in the liner temperature compared to the non-radiation combustor. The radiation models have also down predicted the flame temperature by 200 K and more than 200 K for DOM and P-1 case respectively. The results also showed that the emissivity value had minimal effects on the combustor temperature distribution. The DOM considered being more accurate to estimate the combustor wall and flow temperatures compared to the P-1 radiation method.

Performance of cylindrical and planar meso­scale combustor with double narrow slit flame holder for micropower generator

This research compared the performance of a cylindrical mesoscale combustor against two planar mesoscale combustors, which include the shape of the flame front, temperature of the combustor axis and the combustor wall, and the resulting flammability limit. The combustor used has a circular, square and rectangular cross-section. All three combustors have the same cross-section area and combustion chamber volume. The flame holder used is a double narrow slit. The fuel used is liquefied petroleum gas with a pure oxygen oxidizer. The experiment results showed that the cylindrical combustor produces a more even flame shape that fills the combustion chamber and there is no clear separation between the sides of the flame on each side of the narrow slit. A high ratio of the entrance to average velocity results in a large adverse pressure gradient which generates vortex and recirculation behind the flame holder which gives the mixture a longer chance in the combustion chamber (prolonged residence time). The flame front shape affects the temperature of the combustor axis. The flame front shape that fills the entire combustion chamber has a higher flame temperature than the separate flame front shape. The circular combustor has the highest average axis temperature, but it has the lowest combustor wall temperature. This fact shows that the circular combustor has the smallest heat loss from the flame to the combustor wall. Furthermore, a circular mesoscale combustor has the most extensive stability map. For the same volume, the circular combustor has a lower surface area to volume ratio, thus the heat loss is also low. The dead zone area also becomes narrower, only at a low reactant rate. Rectangular combustors have the largest surface area to volume ratio, thus the losses are also the biggest. Despite the narrowest flammability limits, rectangular combustors have the highest average wall temperatures

Soot formation and combustion characteristics in confined mesoscale combustors under conventional and oxy-combustion conditions (O2/N2 and O2/CO2)

This work investigated soot formation and combustion characteristics in confined mesoscale combustors of two diameters 4 and 6 mm between conventional and oxy-combustion conditions using high resolution transmissions electron microscopy, thermogravimetric analysis and exhaust gases analysis. Results demonstrated that by increasing O2 concentration, the combustion performance can be improved significantly. In 4 mm combustor, both ethylene conversion and mean wall temperature for N2 diluted flame were larger for higher O2 concentration because the reduction of inert diluted gas decreased the heat loss and more O2 content contributed to reactions of more fuel. For N2 diluted flames in 6 mm combustor, soot nanostructure under 21% O2 exhibited amorphous structures but typical fullerene-like structures with more organized fringes could be observed under 30% and 40% O2. The soot carbonization degree increased notably with higher O2 concentration. For the same O2 concentration and combustor, ethylene conversions and temperatures for CO2 diluted flames were always less than those from N2 diluted flames due the larger specific capacity of CO2 than N2. Higher CO concentrations were also detected in exhaust gas from the flame with CO2 dilution than with N2 because CO2 directly participated in the reaction CO2+H⇄CO+OH.

Investigation of self-induced thermoacoustic instabilities in gas turbine combustors

The self-induced thermoacoustic instabilities in partially premixed combustors remain a significant challenge which has received a limited research attention. This numerical work investigates the effect of air-fuel equivalence ratio ∅ on exciting thermoacoustic instabilities and its impact on the characteristics of both the acoustic and combustion fields in a partially premixed swirl combustor. For this purpose, three sets of numerical investigations are studied. The first set is a comparison between the present numerical study and previous experimental work considering the normalized combustor wall temperature. The second set of simulations is performed to predict the behavior of the reacting and non-reacting flows with regard to pressure fluctuations, power spectral density, and the sound pressure levels. The third set of simulations considered the effect of the air-fuel equivalence ratio on the acoustics and combustion characteristics. The results reveal that at an equivalence ratio of 0.5, the sound pressure level for the non-reacting and reacting flows are 98 and 118 dB, respectively. It is concluded that the equivalence ratio plays a crucial rule on exciting combustion instabilities at various amplitudes and frequencies. The sound pressure levels increase with increasing in the air-fuel equivalence ratio due to increase the heat release rate.

Numerical study of effect of front cavity on hydrogen/air premixed combustion in a micro-combustion chamber

The micro-combustion chamber is the key component for micro-TPV systems. To improve the combustor wall temperature level and its uniformity and efficiency an improved flat micro-combustor with a front cavity is built, and the combustion performance of the original and improved combustors of premixed H2/air flames under various inlet velocities and equivalence ratios is numerically investigated. The effects of the front cavity height and length on the outer wall temperature and efficiency are also discussed. The front cavity significantly improves the average outer wall temperature, outer wall temperature uniformity, and combustion efficiency of the micro-combustor, increases the area of the high temperature zone, and enhances the heat transfer between the burned blends and inner walls. The micro-combustor with the front cavity length of 2.0 mm and height of 0.5 mm is suitable for micro-TPV system application due to the relatively high outer wall temperature, combustion efficiency, and the most uniform outer wall temperature.

Influences of initial and transient combustor wall-temperature on thermoacoustic oscillations of a small-scale power generator

Thermoacoustic oscillations are usually investigated for events during which the combustor wall-temperature is constant. Here, we experimentally demonstrate the influence of the transient combustor wall-temperature on the thermoacoustic oscillations of a power generation system for both cold- and warm-start conditions. The experiments are performed for fixed fuel-air equivalence ratios and both fixed and varying volumetric air flowrates. The former is varied between 0.7 and 1.4, and the latter changes between 50 and 130 standard liters per minute. A data acquisition system was used to simultaneously acquire the mixture pressure along with the mixture, the combustor wall-, and the exhaust temperature using a differential pressure transducer and three thermocouples, respectively. Long time-period analysis of the pressure signal suggests the pressure oscillations feature three modes. The dominant frequencies of these modes increase with increasing the fuel-air equivalence ratio; however, they are nearly insensitive to the air volume flowrate. Probability density function, power spectrum density, phase-space trajectory, and the Poincaré map of the pressure oscillations were obtained for a sliding window and for both cold- and warm-start conditions. The results suggest that, for the cold-start condition, the pressure signal transitions from chaotic to limit cycle, chaotic, bursting, and then limit cycle oscillations. For warm-start conditions, however, the pressure signal features a combination of both large- and small-amplitude limit cycle oscillations. For these conditions, as the combustor wall-temperature increases, the possibility of the large-amplitude oscillations occurrence decreases, and that for the small-amplitude oscillations increases. For all tested conditions, the estimated Helmholtz and Strouhal numbers decrease with increasing the Reynolds number, suggesting that the system dynamics is dominated by neither the acoustics nor the vortex-shedding.