Tobias O. Mangold, A. Orchini, C. Paschereit, J. Moeck, Myles D. Bohon
This experimental study explores fundamental qualitative differences of the response of a lean-premixed turbulent swirl flame to azimuthal acoustic excitation in the low- (LF), medium- (MF), and high-frequency (HF) regime. An experimental test rig with a cylindrical combustion chamber is equipped with an array of azimuthally distributed acoustic driver outlets in the burner front plate, allowing for the excitation of the flame with a longitudinal wave, and different azimuthal wave types. Phase-averaged chemiluminescence images show that in the LF regime the flame responds to both longitudinal and azimuthal forcing schemes with hydrodynamically induced intensity fluctuation patterns at relatively small wavelength. Azimuthal forcing generates helical intensity patterns, at the same wavelengths but with lower intensities compared to longitudinal forcing. A fundamentally different flame response is observed in the HF regime: Longitudinal forcing generates only a very weak flame response, and the amplitude of the flame response to azimuthal forcing type depends on the forced azimuthal mode. No hydrodynamic structures are evident anymore, but the flame response now uniformly covers each of the flame sides, indicating a purely acoustic response.
{"title":"Flame Response of a Lean Premixed Swirl Flame to High Frequency Azimuthal Forcing","authors":"Tobias O. Mangold, A. Orchini, C. Paschereit, J. Moeck, Myles D. Bohon","doi":"10.1115/gt2022-84211","DOIUrl":"https://doi.org/10.1115/gt2022-84211","url":null,"abstract":"\u0000 This experimental study explores fundamental qualitative differences of the response of a lean-premixed turbulent swirl flame to azimuthal acoustic excitation in the low- (LF), medium- (MF), and high-frequency (HF) regime. An experimental test rig with a cylindrical combustion chamber is equipped with an array of azimuthally distributed acoustic driver outlets in the burner front plate, allowing for the excitation of the flame with a longitudinal wave, and different azimuthal wave types. Phase-averaged chemiluminescence images show that in the LF regime the flame responds to both longitudinal and azimuthal forcing schemes with hydrodynamically induced intensity fluctuation patterns at relatively small wavelength. Azimuthal forcing generates helical intensity patterns, at the same wavelengths but with lower intensities compared to longitudinal forcing. A fundamentally different flame response is observed in the HF regime: Longitudinal forcing generates only a very weak flame response, and the amplitude of the flame response to azimuthal forcing type depends on the forced azimuthal mode. No hydrodynamic structures are evident anymore, but the flame response now uniformly covers each of the flame sides, indicating a purely acoustic response.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115080482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. P. Beuth, Jakob G. R. von Saldern, T. Kaiser, T. Reichel, C. Paschereit, Bernhard Ćosić, K. Oberleithner
Gas turbine combustors are commonly operated with lean premix flames, allowing for high efficiencies and low emissions. These operating conditions are susceptible to thermoacoustic pulsations, originating from acoustic-flame coupling. To reveal this coupling, experiments or simulations of acoustically forced combustion systems are necessary, which are very challenging for real-scale applications. In this work we investigate the possibility to determine the flame response to acoustic forcing from snapshots of the unforced flow. This approach is based on three central hypothesis: first, the flame response is driven by flow fluctuations, second, these flow fluctuations are dominated by coherent structures driven by hydrodynamic instabilities, and third, these instabilities are driven by stochastic forcing of the background turbulence. As a consequence the dynamics in the natural flow should be low-rank and very similar to those of the acoustically forced system. In this work, the methodology is applied to experimental data of an industry-scale swirl combustor. A resolvent analysis is conducted based on the linearized Navier-Stokes equations to assure analytically the low-rank behavior of the flow dynamics. Then, these dynamics are extracted from flow snapshots using spectral proper orthogonal decomposition (SPOD). The extended SPOD is applied to determine the heat release rate fluctuations that are correlated with the flow dynamics. The low-rank flow and flame dynamics determined from the analytic and data-driven approach are then compared to the flow response determined from a classic phase average of the acoustically forced flow, which allow the research hypothesis to be evaluated. It is concluded that for the present combustor, the flow and flame dynamics are low-rank for a wider frequency range and the response to harmonic forcing can be determined quite accurately from unforced snapshots. The methodology further allows to isolate the frequency range where the flame response is predominantly driven by hydrodynamic instabilites.
{"title":"Flow Response of an Industrial Gas Turbine Combustor To Acoustic Forcing Extracted From Unforced Data","authors":"J. P. Beuth, Jakob G. R. von Saldern, T. Kaiser, T. Reichel, C. Paschereit, Bernhard Ćosić, K. Oberleithner","doi":"10.1115/gt2021-59718","DOIUrl":"https://doi.org/10.1115/gt2021-59718","url":null,"abstract":"\u0000 Gas turbine combustors are commonly operated with lean premix flames, allowing for high efficiencies and low emissions. These operating conditions are susceptible to thermoacoustic pulsations, originating from acoustic-flame coupling. To reveal this coupling, experiments or simulations of acoustically forced combustion systems are necessary, which are very challenging for real-scale applications. In this work we investigate the possibility to determine the flame response to acoustic forcing from snapshots of the unforced flow. This approach is based on three central hypothesis: first, the flame response is driven by flow fluctuations, second, these flow fluctuations are dominated by coherent structures driven by hydrodynamic instabilities, and third, these instabilities are driven by stochastic forcing of the background turbulence. As a consequence the dynamics in the natural flow should be low-rank and very similar to those of the acoustically forced system. In this work, the methodology is applied to experimental data of an industry-scale swirl combustor. A resolvent analysis is conducted based on the linearized Navier-Stokes equations to assure analytically the low-rank behavior of the flow dynamics. Then, these dynamics are extracted from flow snapshots using spectral proper orthogonal decomposition (SPOD). The extended SPOD is applied to determine the heat release rate fluctuations that are correlated with the flow dynamics. The low-rank flow and flame dynamics determined from the analytic and data-driven approach are then compared to the flow response determined from a classic phase average of the acoustically forced flow, which allow the research hypothesis to be evaluated. It is concluded that for the present combustor, the flow and flame dynamics are low-rank for a wider frequency range and the response to harmonic forcing can be determined quite accurately from unforced snapshots. The methodology further allows to isolate the frequency range where the flame response is predominantly driven by hydrodynamic instabilites.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116426915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Patwardhan, Pravin M. Nakod, Stefano Orsino, Rakesh Yadav, Fang Xu, Vishwas Verma
Carbon monoxide (CO) has been identified as one of the regulated pollutants and gas turbine manufacturers target to reduce the CO emission from their gas turbine engines. CO forms primarily when carbonous fuels are not burnt completely, or products of combustion are quenched before completing the combustion. Numerical simulations are effective tools that allow a better understanding of the mechanisms of CO formation in gas turbine engines and are useful in evaluating the effect of different parameters like swirl, fuel atomization, mixing etc. on the overall CO emission for different engine conditions like idle, cruise, approach and take off. In this paper, a thorough assessment of flamelet generated manifold (FGM) combustion model is carried out to predict the qualitative variation and magnitude of CO emission index with the different configurations of a Honeywell test combustor operating with liquid fuel under idle condition, which is the more critical engine condition for CO emission. The different designs of the test combustor are configured in such a way that they yield different levels of CO and hence are ideal to test the accuracy of the combustion model. Large eddy simulation (LES) method is used for capturing the turbulence accurately along with the FGM combustion model that is computationally economical compared to the detailed/reduced chemistry modeling using finite rate combustion model. Liquid fuel spray breakup is modeled using stochastic secondary droplet (SSD) model. Four different configurations of the aviation gas turbine combustor are studied in this work referring to earlier work by Xu et al. [1]. It is shown that the FGM model can predict CO trends accurately. The other global parameters like exit temperature, NOx emissions, pattern factor also show reasonable agreement with the test data. The sensitivity of the CO prediction to the liquid fuel droplet breakup model parameters is also studied in this work. Although the trend of CO variation is captured for different values of breakup parameters, the absolute magnitude of CO emission index differs significantly with the change in the values of breakup parameters suggesting that the spray has a larger impact on the quantitative prediction of CO emission. An accurate prediction of CO trends at idle conditions using FGM model extends the applicability of FGM model to predict different engine operating conditions for different performance criteria accurately.
{"title":"Prediction of CO Emission Index for Aviation Gas Turbine Combustor Using Flamelet Generated Manifold Combustion Model","authors":"S. Patwardhan, Pravin M. Nakod, Stefano Orsino, Rakesh Yadav, Fang Xu, Vishwas Verma","doi":"10.1115/gt2021-59538","DOIUrl":"https://doi.org/10.1115/gt2021-59538","url":null,"abstract":"\u0000 Carbon monoxide (CO) has been identified as one of the regulated pollutants and gas turbine manufacturers target to reduce the CO emission from their gas turbine engines. CO forms primarily when carbonous fuels are not burnt completely, or products of combustion are quenched before completing the combustion. Numerical simulations are effective tools that allow a better understanding of the mechanisms of CO formation in gas turbine engines and are useful in evaluating the effect of different parameters like swirl, fuel atomization, mixing etc. on the overall CO emission for different engine conditions like idle, cruise, approach and take off. In this paper, a thorough assessment of flamelet generated manifold (FGM) combustion model is carried out to predict the qualitative variation and magnitude of CO emission index with the different configurations of a Honeywell test combustor operating with liquid fuel under idle condition, which is the more critical engine condition for CO emission. The different designs of the test combustor are configured in such a way that they yield different levels of CO and hence are ideal to test the accuracy of the combustion model. Large eddy simulation (LES) method is used for capturing the turbulence accurately along with the FGM combustion model that is computationally economical compared to the detailed/reduced chemistry modeling using finite rate combustion model. Liquid fuel spray breakup is modeled using stochastic secondary droplet (SSD) model. Four different configurations of the aviation gas turbine combustor are studied in this work referring to earlier work by Xu et al. [1]. It is shown that the FGM model can predict CO trends accurately. The other global parameters like exit temperature, NOx emissions, pattern factor also show reasonable agreement with the test data. The sensitivity of the CO prediction to the liquid fuel droplet breakup model parameters is also studied in this work. Although the trend of CO variation is captured for different values of breakup parameters, the absolute magnitude of CO emission index differs significantly with the change in the values of breakup parameters suggesting that the spray has a larger impact on the quantitative prediction of CO emission. An accurate prediction of CO trends at idle conditions using FGM model extends the applicability of FGM model to predict different engine operating conditions for different performance criteria accurately.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"135 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124234257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Candy Hernández, V. McDonell, J. Delimont, G. Oskam, M. Ramotowski
In anticipation of increased use of hydrogen as a means of decarbonizing future power generation used widely in combined heat and power plants, studies are underway to understand how hydrogen impacts operability and emissions from existing low emission gas turbines. In the current study, a full-scale annular combustor is used to study how added hydrogen to methane (as a proxy for natural gas) impacts lean blow-off limits. Of particular interest is understanding if hydrogen can be used strategically to extend low emissions operation at lower load. This would facilitate use of gas turbines to offset intermittent renewable power which is becoming increasing integrated into microgrid environments where combined heat and power system are prevalent. A combined experimental and numerical approach is taken. Tests were carried out at Southwest Research Institute using a full-scale annular combustor test rig at elevated temperatures and atmospheric pressure. The individual fuel injectors used were piloted injectors based on natural gas injectors used in practice. Various blends of hydrogen and methane were tested for different scaled load conditions and different pilot to main fuel splits. Besides identifying the overall equivalence ratio at blow-off, measurements also included temperature uniformity at the exit plane and imaging of the reaction. To complement and extend the study a chemical reactor network approach was also applied. The reactor network was initially validated on a prior study involving use of a piloted model combustor. The reactor network was applied to the current configuration and further tuned to align with the measured data. The agreement between the reactor network blow-off and measured blow-off was reasonable. The validated reactor network was then used in combination with a statistically designed simulation matrix to derive a design tool. The tool is then used to estimate other performance features including CO emissions near LBO and the impacts of ambient humidity and the presence of higher hydrocarbons typically found in natural gas. The design tool quantifies the extent to which hydrogen content and pilot percentage can extended part load operability for the full annular combustor system.
{"title":"Exploring Use of Hydrogen for Extending Operability of a Full-Scale Annular Combustor","authors":"Candy Hernández, V. McDonell, J. Delimont, G. Oskam, M. Ramotowski","doi":"10.1115/gt2021-59419","DOIUrl":"https://doi.org/10.1115/gt2021-59419","url":null,"abstract":"\u0000 In anticipation of increased use of hydrogen as a means of decarbonizing future power generation used widely in combined heat and power plants, studies are underway to understand how hydrogen impacts operability and emissions from existing low emission gas turbines. In the current study, a full-scale annular combustor is used to study how added hydrogen to methane (as a proxy for natural gas) impacts lean blow-off limits. Of particular interest is understanding if hydrogen can be used strategically to extend low emissions operation at lower load. This would facilitate use of gas turbines to offset intermittent renewable power which is becoming increasing integrated into microgrid environments where combined heat and power system are prevalent. A combined experimental and numerical approach is taken. Tests were carried out at Southwest Research Institute using a full-scale annular combustor test rig at elevated temperatures and atmospheric pressure. The individual fuel injectors used were piloted injectors based on natural gas injectors used in practice. Various blends of hydrogen and methane were tested for different scaled load conditions and different pilot to main fuel splits. Besides identifying the overall equivalence ratio at blow-off, measurements also included temperature uniformity at the exit plane and imaging of the reaction. To complement and extend the study a chemical reactor network approach was also applied. The reactor network was initially validated on a prior study involving use of a piloted model combustor. The reactor network was applied to the current configuration and further tuned to align with the measured data. The agreement between the reactor network blow-off and measured blow-off was reasonable. The validated reactor network was then used in combination with a statistically designed simulation matrix to derive a design tool. The tool is then used to estimate other performance features including CO emissions near LBO and the impacts of ambient humidity and the presence of higher hydrocarbons typically found in natural gas. The design tool quantifies the extent to which hydrogen content and pilot percentage can extended part load operability for the full annular combustor system.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"496 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134429201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Gong, D. Fredrich, A. Marquis, W. Jones, I. Boxx
Large eddy simulations (LES) of premixed hydrogen-enriched swirling flames were performed to investigate the flame topology and combustion instabilities with different hydrogen concentrations. A compressible LES approach is utilised to account for the self-excited combustion dynamics. A transported probability density function (pd f) approach is adopted to account for sub-grid scale (sgs) turbulence-chemistry interaction, and the solution to the joint sgs – pd f evolution equation of the scalars is obtained by the stochastic field method. The chemistry is represented using a reduced chemical reaction mechanism containing 15 reaction steps and 19 species. The results revealed that as the concentration of hydrogen increases, the flame is shortened in the injecting direction and more confined in the cross-sectional direction, which is consistent with experimental observations. The self-excited limit-cycle oscillations for all considered cases were successfully reproduced, with the predicted peak frequencies of the chamber pressure spectra in excellent agreement with the measured values. The feedback loop of the oscillations is successfully captured and analysed with the temporal evolution of axial velocity and heat release presented.
{"title":"Thermoacoustic Instabilities of Hydrogen-Enriched Partially Premixed Flames in a Swirl Combustor","authors":"Y. Gong, D. Fredrich, A. Marquis, W. Jones, I. Boxx","doi":"10.1115/gt2021-60009","DOIUrl":"https://doi.org/10.1115/gt2021-60009","url":null,"abstract":"\u0000 Large eddy simulations (LES) of premixed hydrogen-enriched swirling flames were performed to investigate the flame topology and combustion instabilities with different hydrogen concentrations. A compressible LES approach is utilised to account for the self-excited combustion dynamics. A transported probability density function (pd f) approach is adopted to account for sub-grid scale (sgs) turbulence-chemistry interaction, and the solution to the joint sgs – pd f evolution equation of the scalars is obtained by the stochastic field method. The chemistry is represented using a reduced chemical reaction mechanism containing 15 reaction steps and 19 species. The results revealed that as the concentration of hydrogen increases, the flame is shortened in the injecting direction and more confined in the cross-sectional direction, which is consistent with experimental observations. The self-excited limit-cycle oscillations for all considered cases were successfully reproduced, with the predicted peak frequencies of the chamber pressure spectra in excellent agreement with the measured values. The feedback loop of the oscillations is successfully captured and analysed with the temporal evolution of axial velocity and heat release presented.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126858540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The flame dynamics during unstable combustion occurring in a model gas turbine combustor under fuel-rich conditions analogous to idle and sub-idle conditions in an aero-engine is characterized by simultaneous measurement of flame emissions and dynamic pressure fluctuation as well as high-speed imaging. Pressure fluctuation during unstable combustion causes linearly increasing velocity fluctuation at the combustor inlet. The fluctuation level of CH*-band emission which is mainly from soot linearly increases with respect to the combustor inlet velocity fluctuation up to ∼40% of mean velocity while that of OH*-band emission which is from OH* is non-linear. Highspeed imaging shows that the OH*-band emission fluctuation occurs mainly near the dump plane but the CH*-band emission fluctuation occurs downstream of it. When the pressure fluctuation is more than 1% of mean pressure, there exists an almost constant phase delay between emissions from OH*- and CH*-band and dynamic pressure fluctuations and the phase delay satisfies the Rayleigh criterion. In addition, the Rayleigh integral made over the whole flame and one period of oscillation of thermoacoustic instability becomes positive. These may suggest either OH*- or CH*-band emission can be used as a representation of heat release. However, the observations that the mean OH*-band emission intensity increases but the mean CH*-band emission intensity does not as the mean equivalence ratio increases and the fluctuation level of emission in OH*-band increases but that in CH*-band emission does not as the pressure fluctuation level increases strongly suggest that the emission from OH*-band should be considered as a representation of heat release for sooty flames under the employed operating condition in this study.
{"title":"Characterization of Dynamics of Unstable Fuel-Rich Flame","authors":"M. Weber, J. Song, J. Lee","doi":"10.1115/gt2021-60121","DOIUrl":"https://doi.org/10.1115/gt2021-60121","url":null,"abstract":"\u0000 The flame dynamics during unstable combustion occurring in a model gas turbine combustor under fuel-rich conditions analogous to idle and sub-idle conditions in an aero-engine is characterized by simultaneous measurement of flame emissions and dynamic pressure fluctuation as well as high-speed imaging. Pressure fluctuation during unstable combustion causes linearly increasing velocity fluctuation at the combustor inlet. The fluctuation level of CH*-band emission which is mainly from soot linearly increases with respect to the combustor inlet velocity fluctuation up to ∼40% of mean velocity while that of OH*-band emission which is from OH* is non-linear. Highspeed imaging shows that the OH*-band emission fluctuation occurs mainly near the dump plane but the CH*-band emission fluctuation occurs downstream of it. When the pressure fluctuation is more than 1% of mean pressure, there exists an almost constant phase delay between emissions from OH*- and CH*-band and dynamic pressure fluctuations and the phase delay satisfies the Rayleigh criterion. In addition, the Rayleigh integral made over the whole flame and one period of oscillation of thermoacoustic instability becomes positive. These may suggest either OH*- or CH*-band emission can be used as a representation of heat release. However, the observations that the mean OH*-band emission intensity increases but the mean CH*-band emission intensity does not as the mean equivalence ratio increases and the fluctuation level of emission in OH*-band increases but that in CH*-band emission does not as the pressure fluctuation level increases strongly suggest that the emission from OH*-band should be considered as a representation of heat release for sooty flames under the employed operating condition in this study.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122653314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The aircraft Auxiliary Power Unit (APU) is required to provide power to start the main engines, conditioned air and power when there are no facilities available and, most importantly, emergency power during flight operation. Given the primary purpose of providing backup power, APUs have historically been designed to be extremely reliable while minimizing weight and fabrication cost. Since APUs are operated at airports especially during taxi operations, the emissions from the APUs contribute to local air quality. There is clearly significant regulatory and public interest in reducing emissions from all sources at airports, including from APUs. As such, there is a need to develop technologies that reduce criteria pollutants, namely oxides of nitrogen (NOx), unburned hydrocarbons (UHC), carbon monoxide (CO) and smoke (SN) from aircraft APUs. Honeywell has developed a Low-Emissions (Low-E) combustion system technology for the 131-9 and HGT750 family of APUs to provide significant reduction in pollutants for narrow-body aircraft application. This article focuses on the combustor technology and processes that have been successfully utilized in this endeavor, with an emphasis on abating NOx. This paper describes the 131-9/HGT750 APU, the requirements and challenges for small gas turbine engines, and the selected strategy of Rich-Quench-Lean (RQL) combustion. Analytical and experimental results are presented for the current generation of APU combustion systems as well as the Low-E system. The implementation of RQL aerodynamics is well understood within the aero-gas turbine engine industry, but the application of RQL technology in a configuration with tangential liquid fuel injection which is also required to meet altitude ignition at 41,000 ft is the novelty of this development. The Low-E combustion system has demonstrated more than 25% reduction in NOx (dependent on the cycle of operation) vs. the conventional 131-9 combustion system while meeting significant margins in other criteria pollutants. In addition, the Low-E combustion system achieved these successes as a “drop-in” configuration within the existing envelope, and without significantly impacting combustor/turbine durability, combustor pressure drop, or lean stability.
{"title":"Low-Emissions Technology Development for Auxiliary Power Unit Combustion Systems","authors":"Thomas Bronson, R. Dudebout, N. Rudrapatna","doi":"10.1115/gt2021-60228","DOIUrl":"https://doi.org/10.1115/gt2021-60228","url":null,"abstract":"\u0000 The aircraft Auxiliary Power Unit (APU) is required to provide power to start the main engines, conditioned air and power when there are no facilities available and, most importantly, emergency power during flight operation. Given the primary purpose of providing backup power, APUs have historically been designed to be extremely reliable while minimizing weight and fabrication cost. Since APUs are operated at airports especially during taxi operations, the emissions from the APUs contribute to local air quality. There is clearly significant regulatory and public interest in reducing emissions from all sources at airports, including from APUs. As such, there is a need to develop technologies that reduce criteria pollutants, namely oxides of nitrogen (NOx), unburned hydrocarbons (UHC), carbon monoxide (CO) and smoke (SN) from aircraft APUs.\u0000 Honeywell has developed a Low-Emissions (Low-E) combustion system technology for the 131-9 and HGT750 family of APUs to provide significant reduction in pollutants for narrow-body aircraft application. This article focuses on the combustor technology and processes that have been successfully utilized in this endeavor, with an emphasis on abating NOx.\u0000 This paper describes the 131-9/HGT750 APU, the requirements and challenges for small gas turbine engines, and the selected strategy of Rich-Quench-Lean (RQL) combustion. Analytical and experimental results are presented for the current generation of APU combustion systems as well as the Low-E system. The implementation of RQL aerodynamics is well understood within the aero-gas turbine engine industry, but the application of RQL technology in a configuration with tangential liquid fuel injection which is also required to meet altitude ignition at 41,000 ft is the novelty of this development. The Low-E combustion system has demonstrated more than 25% reduction in NOx (dependent on the cycle of operation) vs. the conventional 131-9 combustion system while meeting significant margins in other criteria pollutants. In addition, the Low-E combustion system achieved these successes as a “drop-in” configuration within the existing envelope, and without significantly impacting combustor/turbine durability, combustor pressure drop, or lean stability.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"360 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124535395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yongtao Fan, Taku Tsujimura, N. Iki, O. Kurata, H. Furutani
Large-scale electric power generation with hydrogen-fired gas turbines is key to the realization of zero-emission society. One challenge of premixed hydrogen combustion is the flashback associated with high burning velocity. On the other hand, non-premixed (diffusion) hydrogen-air combustion produces high level of NOx due to the high flame temperature. In order to reduce NOx, a semi-closed gas turbine cycles employing the hydrogen-oxygen combustion has been proposed. In the present study, we developed a non-premixed hydrogen-oxygen burner with sub-millimeter nozzles to form two oxygen jets impinging on the hydrogen jet at an acute angle. Compared to conventional burners with co-flow jets, forced mixing of hydrogen and oxygen occurs due to the impingement. It is expected that the flame holding as well as the combustion efficiency can be improved. High-speed Schlieren and OH* chemiluminescence images of the hydrogen flame with/without the oxygen jet impingement in a pressure vessel were captured to examine the instantaneous flame structure. Flammability and flame structure have been investigated at various jet velocity and pressure conditions. It was found that without the oxygen jet impingement the flame becomes longer with increasing the hydrogen velocity. Lifted flames were observed at the velocity over 200 m/s. The lift position moves gradually downstream with further increasing the velocity. On the other hand, with increasing the velocity of the oxygen jet impinged to the hydrogen jet, a V-shaped flame front stabilized at the impinging position was observed. It was also found that flame holding is improved at high pressure. Based on the impinged jet flame concept, prototype multi-cluster burners with sub-millimeter nozzle arrays were designed and fabricated using the Inconel alloy 3D printing technology.
{"title":"Investigation of Non-Premixed Hydrogen-Oxygen Impinged Jet Flame Under Steam Dilution","authors":"Yongtao Fan, Taku Tsujimura, N. Iki, O. Kurata, H. Furutani","doi":"10.1115/gt2021-59425","DOIUrl":"https://doi.org/10.1115/gt2021-59425","url":null,"abstract":"\u0000 Large-scale electric power generation with hydrogen-fired gas turbines is key to the realization of zero-emission society. One challenge of premixed hydrogen combustion is the flashback associated with high burning velocity. On the other hand, non-premixed (diffusion) hydrogen-air combustion produces high level of NOx due to the high flame temperature. In order to reduce NOx, a semi-closed gas turbine cycles employing the hydrogen-oxygen combustion has been proposed. In the present study, we developed a non-premixed hydrogen-oxygen burner with sub-millimeter nozzles to form two oxygen jets impinging on the hydrogen jet at an acute angle. Compared to conventional burners with co-flow jets, forced mixing of hydrogen and oxygen occurs due to the impingement. It is expected that the flame holding as well as the combustion efficiency can be improved. High-speed Schlieren and OH* chemiluminescence images of the hydrogen flame with/without the oxygen jet impingement in a pressure vessel were captured to examine the instantaneous flame structure. Flammability and flame structure have been investigated at various jet velocity and pressure conditions. It was found that without the oxygen jet impingement the flame becomes longer with increasing the hydrogen velocity. Lifted flames were observed at the velocity over 200 m/s. The lift position moves gradually downstream with further increasing the velocity. On the other hand, with increasing the velocity of the oxygen jet impinged to the hydrogen jet, a V-shaped flame front stabilized at the impinging position was observed. It was also found that flame holding is improved at high pressure. Based on the impinged jet flame concept, prototype multi-cluster burners with sub-millimeter nozzle arrays were designed and fabricated using the Inconel alloy 3D printing technology.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130581000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Petersen, O. Mathieu, James C. Thomas, S. Cooper, D. S. Teitge, Raquel Juárez, Nobel Gutierrez, Chad V. Mashuga
Because of the high temperatures involved, undesirable ignition events can happen during gas turbine operation, often necessitating expensive down time and repairs. The ignition events are frequently linked to the lubricant, a flammable mixture of large hydrocarbons with a very low vapor pressure. To understand better the role of the lubricant in such ignition events, increased understanding of the fundamental thermal and oxidation characteristics of such oils is needed. To this end, a suite of different tests has been set up and demonstrated at the TEES Turbomachinery Laboratory at Texas A&M University (TAMU) to study various aspects of lubrication oil breakdown and oxidation at elevated temperatures, mostly those related to their coking and ignition behaviors. Five types of tests have been implemented: ignition delay time measurements using a shock tube; hot surface ignition (HSI); autoignition temperature (AIT) determination; thermal cook-off under controlled heating; and a high-temperature coking experiment. Such tests can be used both for fundamental understanding of how lube oils burn and for comparing the reactivity of various types and grades of oil. Each technique at TAMU is briefly described in this paper as they pertain to gas turbine lube oils, and sample results are presented for a common lubrication oil, Mobil DTE 732. For this oil, the HSI tests produced a lowest temperature without ignition of 510°C, and in shock-tube measurements, lower-temperature ignition kinetics are observed below about 1300 K, even at 1 atm. Typical AIT values for oils have been found to be around 370°C but do vary amongst brands, types, and level of degradation. The measured temperatures for the exothermic and boiling events were measured as 166±2 °C and 277±4 °C using the cook-off rig.
{"title":"Combustion and Oxidation of Lube Oils at Gas Turbine Conditions: Experimental Methods","authors":"E. Petersen, O. Mathieu, James C. Thomas, S. Cooper, D. S. Teitge, Raquel Juárez, Nobel Gutierrez, Chad V. Mashuga","doi":"10.1115/gt2021-60319","DOIUrl":"https://doi.org/10.1115/gt2021-60319","url":null,"abstract":"\u0000 Because of the high temperatures involved, undesirable ignition events can happen during gas turbine operation, often necessitating expensive down time and repairs. The ignition events are frequently linked to the lubricant, a flammable mixture of large hydrocarbons with a very low vapor pressure. To understand better the role of the lubricant in such ignition events, increased understanding of the fundamental thermal and oxidation characteristics of such oils is needed. To this end, a suite of different tests has been set up and demonstrated at the TEES Turbomachinery Laboratory at Texas A&M University (TAMU) to study various aspects of lubrication oil breakdown and oxidation at elevated temperatures, mostly those related to their coking and ignition behaviors. Five types of tests have been implemented: ignition delay time measurements using a shock tube; hot surface ignition (HSI); autoignition temperature (AIT) determination; thermal cook-off under controlled heating; and a high-temperature coking experiment. Such tests can be used both for fundamental understanding of how lube oils burn and for comparing the reactivity of various types and grades of oil. Each technique at TAMU is briefly described in this paper as they pertain to gas turbine lube oils, and sample results are presented for a common lubrication oil, Mobil DTE 732. For this oil, the HSI tests produced a lowest temperature without ignition of 510°C, and in shock-tube measurements, lower-temperature ignition kinetics are observed below about 1300 K, even at 1 atm. Typical AIT values for oils have been found to be around 370°C but do vary amongst brands, types, and level of degradation. The measured temperatures for the exothermic and boiling events were measured as 166±2 °C and 277±4 °C using the cook-off rig.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128909195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Shamma, S. Harth, N. Zarzalis, D. Trimis, S. Hoffmann, R. Koch, H. Bauer, L. Langone, S. Galeotti, A. Andreini
The main objective of this research is to assess an innovative, low nitrogen oxides emission combustor concept, which has the potential to achieve the long term European emissions goals for aircraft engines. Lean lifted spray flames and their very low nitrogen oxides emissions are combined with an inclination of burners in annular combustor leading to a more compact combustor with superior stability range. The presented combustor concept was developed in the frame of the European research project CHAIRLIFT (Compact Helical Arranged combustoRs with lean LIFTed flames). CHAIRLIFT combustor concept is based on “low swirl” lean lifted spray flames, which features a high degree of premixing and consequently significantly reduced nitrogen oxides emissions and flashback risk compared to conventional swirl stabilized flames. In the CHAIRLIFT combustor concept, the lifted flames are combined with Short Helical Combustors arrangement to attain stable combustion by tilting the axis of the flames relative to the axis of the turbine to enhance the interaction of adjacent flames in a circumferential direction. A series of experimental tests were conducted at a multi-burner array test rig consisting of up to five modular burners at different burner inclination angles (0° and 45°), equivalence ratios, and relative air pressure drop at ambient conditions. For all investigated configurations, a remarkable high lean blow out for non-piloted burners (ϕLBO = 0.29–0.37), was measured. The multi-burner configurations were observed having a superior stability range in contrast to the typical decrease in stability from single to high swirl multi-burner. The unwanted flow deflection of highly swirled flames in Short Helical Combustors arrangement, could be avoided with the investigated low swirl lifted flames. Moreover, the flame chemiluminescence (OH*) measurements were used to provide a qualitative characterization of the flame topology. Complementary numerical investigations were carried out using different numbers of burners to evaluate the effect of boundary conditions.
{"title":"Investigation of Adjacent Lifted Flames Interaction in an Inline and Inclined Multi-Burner Arrangement","authors":"M. Shamma, S. Harth, N. Zarzalis, D. Trimis, S. Hoffmann, R. Koch, H. Bauer, L. Langone, S. Galeotti, A. Andreini","doi":"10.1115/gt2021-59941","DOIUrl":"https://doi.org/10.1115/gt2021-59941","url":null,"abstract":"\u0000 The main objective of this research is to assess an innovative, low nitrogen oxides emission combustor concept, which has the potential to achieve the long term European emissions goals for aircraft engines. Lean lifted spray flames and their very low nitrogen oxides emissions are combined with an inclination of burners in annular combustor leading to a more compact combustor with superior stability range. The presented combustor concept was developed in the frame of the European research project CHAIRLIFT (Compact Helical Arranged combustoRs with lean LIFTed flames). CHAIRLIFT combustor concept is based on “low swirl” lean lifted spray flames, which features a high degree of premixing and consequently significantly reduced nitrogen oxides emissions and flashback risk compared to conventional swirl stabilized flames. In the CHAIRLIFT combustor concept, the lifted flames are combined with Short Helical Combustors arrangement to attain stable combustion by tilting the axis of the flames relative to the axis of the turbine to enhance the interaction of adjacent flames in a circumferential direction. A series of experimental tests were conducted at a multi-burner array test rig consisting of up to five modular burners at different burner inclination angles (0° and 45°), equivalence ratios, and relative air pressure drop at ambient conditions. For all investigated configurations, a remarkable high lean blow out for non-piloted burners (ϕLBO = 0.29–0.37), was measured. The multi-burner configurations were observed having a superior stability range in contrast to the typical decrease in stability from single to high swirl multi-burner. The unwanted flow deflection of highly swirled flames in Short Helical Combustors arrangement, could be avoided with the investigated low swirl lifted flames. Moreover, the flame chemiluminescence (OH*) measurements were used to provide a qualitative characterization of the flame topology. Complementary numerical investigations were carried out using different numbers of burners to evaluate the effect of boundary conditions.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125663318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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