This study investigates the pressure gain and its improvement on the gas turbine performance. The combustor is comprised from two combustion chambers. One chamber A conducts pulse combustion and the other chamber B conducts continuous, constant-pressure combustion. The burned gases of each chamber are mixed and enter the turbine. The detail time variation of chamber pressure as well as turbine inlet and compressor outlet under the pulse combustion mode were experimentally investigated. The pulse combustion in the chamber A generated the pressure wave that propagated not only downstream to the turbine inlet but also chamber upstream. This pressure wave stagnated the gas flow from the compressor in the chamber A. The gas flow velocities at the chamber inlet and outlet of chamber A were measured. The results showed the large velocity variation in one cycle under the pulse combustion mode. Based on the velocity, the cycle-averaged pressures in the chamber A were evaluated by mass-averaging method. The estimated cycle-averaged pressure ratio became 1.067 means that a pressure gain of 6.7% was obtained in the chamber A. Although the hydrogen fuel mass flow rate in the pulse combustion mode was larger than that in the normal combustion mode, the apparent higher value of specific output power in the pulse combustion mode than in the normal combustion mode demonstrated the feature of pressure-gain combustion.
{"title":"Evaluation of Pressure Gain and Turbine Inlet Conditions in a Pulse Combustion Gas Turbine","authors":"Takashi Sakurai, Takehiro Sekiguchi, Sora Inoue","doi":"10.1115/gt2022-83528","DOIUrl":"https://doi.org/10.1115/gt2022-83528","url":null,"abstract":"\u0000 This study investigates the pressure gain and its improvement on the gas turbine performance. The combustor is comprised from two combustion chambers. One chamber A conducts pulse combustion and the other chamber B conducts continuous, constant-pressure combustion. The burned gases of each chamber are mixed and enter the turbine. The detail time variation of chamber pressure as well as turbine inlet and compressor outlet under the pulse combustion mode were experimentally investigated. The pulse combustion in the chamber A generated the pressure wave that propagated not only downstream to the turbine inlet but also chamber upstream. This pressure wave stagnated the gas flow from the compressor in the chamber A. The gas flow velocities at the chamber inlet and outlet of chamber A were measured. The results showed the large velocity variation in one cycle under the pulse combustion mode. Based on the velocity, the cycle-averaged pressures in the chamber A were evaluated by mass-averaging method. The estimated cycle-averaged pressure ratio became 1.067 means that a pressure gain of 6.7% was obtained in the chamber A. Although the hydrogen fuel mass flow rate in the pulse combustion mode was larger than that in the normal combustion mode, the apparent higher value of specific output power in the pulse combustion mode than in the normal combustion mode demonstrated the feature of pressure-gain combustion.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"381 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":"122841887","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}
Nunzio Dimola, M. Stefanizzi, T. Capurso, T. Schuller, M. Torresi, S. Camporeale
Given the current practice to perform lean-premixed combustion to decrease NOx emissions, thermoacoustic instabilities have become one of the major drawbacks in gas turbine combustors. The necessity to control and limit such a deleterious phenomenon is mandatory to avoid structural damage of the burner. It has been demonstrated that perforated liners, if conveniently designed, can be very effective in reducing acoustic oscillations inside gas turbine combustors. Studying perforated plates traversed by bias flow can give a useful insight on sound absorption properties of liners, rather than investigate complex geometries. The present paper aims to carry out a numerically cost-effective, but reliable, CFD analysis to predict the acoustic impedance of perforated plates traversed by bias flow, and to grasp the details of the sound dissipation process. 2D axisymmetric simulations have been carried out and the governing equations solved by using the commercial code ANSYS Fluent®. Hypotheses, boundaries and operating conditions are described, focusing on the role of the Non-Reflecting-Boundary-Condition (NRBC) and the Transparent-Flow-Forcing condition (TFF) in treating acoustic waves. Numerical results are compared both with linear analytical models and experimental data from a case study, by proving a fast and reliable prediction of the acoustic response. Furthermore, effects of increasing bias flow temperature on the sound absorption property have been investigated, showing an increase in acoustic power losses as temperature rises. The proposed CFD model (2D-axisymmetric) proved to be a valid and versatile tool in evaluating the acoustic response of perforated plates under different operating conditions.
{"title":"Cost-Effective CFD Analysis of the Acoustic Response of a Perforated Plate","authors":"Nunzio Dimola, M. Stefanizzi, T. Capurso, T. Schuller, M. Torresi, S. Camporeale","doi":"10.1115/gt2022-82670","DOIUrl":"https://doi.org/10.1115/gt2022-82670","url":null,"abstract":"\u0000 Given the current practice to perform lean-premixed combustion to decrease NOx emissions, thermoacoustic instabilities have become one of the major drawbacks in gas turbine combustors. The necessity to control and limit such a deleterious phenomenon is mandatory to avoid structural damage of the burner. It has been demonstrated that perforated liners, if conveniently designed, can be very effective in reducing acoustic oscillations inside gas turbine combustors. Studying perforated plates traversed by bias flow can give a useful insight on sound absorption properties of liners, rather than investigate complex geometries. The present paper aims to carry out a numerically cost-effective, but reliable, CFD analysis to predict the acoustic impedance of perforated plates traversed by bias flow, and to grasp the details of the sound dissipation process. 2D axisymmetric simulations have been carried out and the governing equations solved by using the commercial code ANSYS Fluent®. Hypotheses, boundaries and operating conditions are described, focusing on the role of the Non-Reflecting-Boundary-Condition (NRBC) and the Transparent-Flow-Forcing condition (TFF) in treating acoustic waves. Numerical results are compared both with linear analytical models and experimental data from a case study, by proving a fast and reliable prediction of the acoustic response. Furthermore, effects of increasing bias flow temperature on the sound absorption property have been investigated, showing an increase in acoustic power losses as temperature rises. The proposed CFD model (2D-axisymmetric) proved to be a valid and versatile tool in evaluating the acoustic response of perforated plates under different operating conditions.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"122 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":"121362041","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 emission characteristics of a model centrally staged lean premixed prevaporized (LPP) combustor was investigated under near-critical and supercritical main fuel injections. The Chinese aviation kerosene, RP-3, with its critical temperature and pressure of 651 K and 2.35 MPa, was preheated from 500 to 740 K and pressurized from 2.0 to 3.5 MPa before being injected into the combustor. The combustor liner consists of ceramic matrix composites (CMC), which are installed on a water-cooling frame. Therefore, the combustor features a high dome air ratio (95% of the total air) by removing both primary and dilution holes and redirecting the liner cooling air to the dome. The overall fuel-to-air ratio was varied from 0.030 to 0.053. The emissions at the combustor outlet were measured at various operating conditions in the range of inlet air temperatures from 600 to 840 K and pressures from 2.0 to 2.8 MPa. The results showed that EINOx decreases about 40% as the injection temperature increase from 500 K to 740 K at 2.0 to 2.4 MPa injection pressure. It indicates that the transition from liquid fuel to supercritical fuel drastically reduces fuel density and surface tension. Increasing injection fuel temperature significantly improves the fuel/air mixing and avoids hot spot formation that favors NOx formation. Both EICO and EIUHC decrease slightly with increasing fuel injection temperature, suggesting a weak relation between the combustion efficiency and fuel thermodynamic state. The finding of the current study suggests that the NOx emissions are affected by the premixing quality of the main injector and may be reduced by injecting supercritical kerosene.
{"title":"Emission Characteristics of Aviation Kerosene Combustion Under Near-Critical and Supercritical Fuel Injections","authors":"Yue Yang, Xin Xue, X. Hui, Yaxin Tan, Wei Wei, Cheng Liu, Yuzhen Lin","doi":"10.1115/gt2022-82070","DOIUrl":"https://doi.org/10.1115/gt2022-82070","url":null,"abstract":"The emission characteristics of a model centrally staged lean premixed prevaporized (LPP) combustor was investigated under near-critical and supercritical main fuel injections. The Chinese aviation kerosene, RP-3, with its critical temperature and pressure of 651 K and 2.35 MPa, was preheated from 500 to 740 K and pressurized from 2.0 to 3.5 MPa before being injected into the combustor. The combustor liner consists of ceramic matrix composites (CMC), which are installed on a water-cooling frame. Therefore, the combustor features a high dome air ratio (95% of the total air) by removing both primary and dilution holes and redirecting the liner cooling air to the dome. The overall fuel-to-air ratio was varied from 0.030 to 0.053. The emissions at the combustor outlet were measured at various operating conditions in the range of inlet air temperatures from 600 to 840 K and pressures from 2.0 to 2.8 MPa. The results showed that EINOx decreases about 40% as the injection temperature increase from 500 K to 740 K at 2.0 to 2.4 MPa injection pressure. It indicates that the transition from liquid fuel to supercritical fuel drastically reduces fuel density and surface tension. Increasing injection fuel temperature significantly improves the fuel/air mixing and avoids hot spot formation that favors NOx formation. Both EICO and EIUHC decrease slightly with increasing fuel injection temperature, suggesting a weak relation between the combustion efficiency and fuel thermodynamic state. The finding of the current study suggests that the NOx emissions are affected by the premixing quality of the main injector and may be reduced by injecting supercritical kerosene.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"4 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":"128015180","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}
Liang Zhang, Xin Xue, Qian Yang, Huiru Wang, Jibao Li
The stratified swirl combustor is generally used in an advanced aero-engine, in order to achieve a low emission and wide stabilization at the same time. The complex interactions between the pilot stage and main stage can determine the flame structure, flow field, further affecting the emission formation and stabilization. The present study investigates the interaction between pilot flame and flow field of a stratified swirl combustor, by varying the outlet angles and swirl numbers of the pilot stage swirler. Flame structures and flow fields are obtained while only the pilot stage working. The flame structures are represented by the OH* chemiluminescence (OH-CL) image with Abel deconvolution, non-reacting and reacting flow fields are measured by Particle Image Velocimetry (PIV). The results show that heat release from the pilot flame causes rapid expansion of the pilot gas which may significantly change flow field distribution. Two types of flame structures and flow fields are formed with different outlet angles and swirl numbers of pilot stage. The correspondence between the flame structure and flow field is obtained. For large outlet angle or high swirl number, a M-shape flame combining with a typical stratified swirl flow field and converged pilot and main flow jet are observed, including a large main recirculation zone (MRZ), a lip recirculation zone (LRZ), and a corner recirculation zone (CRZ). For small outlet angle and low swirl number, the flame structure presents a lifted inverted U-shape flame, pilot and main stage jet are separated, there are a small pilot recirculation zone (PRZ), a main recirculation zone (MRZ) and a corner recirculation zone (CRZ) in the combustor. The MRZ is broken into two parts by the accelerated of pilot flow, the LRZ is merged into the MRZ.
{"title":"Experiment Study of Pilot Stage Swirler Outlet Angles and Swirl Number on Flame Structures and Flow Field in a Stratified Swirl Combustor","authors":"Liang Zhang, Xin Xue, Qian Yang, Huiru Wang, Jibao Li","doi":"10.1115/gt2022-83221","DOIUrl":"https://doi.org/10.1115/gt2022-83221","url":null,"abstract":"\u0000 The stratified swirl combustor is generally used in an advanced aero-engine, in order to achieve a low emission and wide stabilization at the same time. The complex interactions between the pilot stage and main stage can determine the flame structure, flow field, further affecting the emission formation and stabilization. The present study investigates the interaction between pilot flame and flow field of a stratified swirl combustor, by varying the outlet angles and swirl numbers of the pilot stage swirler. Flame structures and flow fields are obtained while only the pilot stage working. The flame structures are represented by the OH* chemiluminescence (OH-CL) image with Abel deconvolution, non-reacting and reacting flow fields are measured by Particle Image Velocimetry (PIV). The results show that heat release from the pilot flame causes rapid expansion of the pilot gas which may significantly change flow field distribution. Two types of flame structures and flow fields are formed with different outlet angles and swirl numbers of pilot stage. The correspondence between the flame structure and flow field is obtained. For large outlet angle or high swirl number, a M-shape flame combining with a typical stratified swirl flow field and converged pilot and main flow jet are observed, including a large main recirculation zone (MRZ), a lip recirculation zone (LRZ), and a corner recirculation zone (CRZ). For small outlet angle and low swirl number, the flame structure presents a lifted inverted U-shape flame, pilot and main stage jet are separated, there are a small pilot recirculation zone (PRZ), a main recirculation zone (MRZ) and a corner recirculation zone (CRZ) in the combustor. The MRZ is broken into two parts by the accelerated of pilot flow, the LRZ is merged into the MRZ.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"15 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":"133906885","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}
T. J. P. Karpowski, F. Ferraro, M. Steinhausen, S. Popp, C. Arndt, Christian Kraus, H. Bockhorn, W. Meier, C. Hasse
In this work, the thermo-acoustic instabilities of a gas turbine model combustor, the so-called SFB606 combustor, are numerically investigated using Large Eddy Simulation (LES) combined with tabulated chemistry and Artificial Thickened Flame (ATF) approach. The main focus is a detailed analysis of the thermo-acoustic cycle and the accompanied equivalence ratio oscillations and their associated convective time delay. In particular, the variations of the thermo-chemical state and flame characteristics over the thermo-acoustic cycle are investigated. For the operating point flame B (Pth = 25kW, Φ = 0.7), the burner exhibits thermo-acoustic instabilities with a dominant frequency of 392 Hz, the acoustic eigenmode of the inner air inlet duct. These oscillations are accompanied by an equivalence ratio oscillation, which exhibits a convective time delay between the injection in the inner swirler and the flame zone. Two LES, one adiabatic and one accounting for heat losses at the walls by prescribing the wall temperatures from experimental data and Conjugated Heat Transfer (CHT) simulations, are conducted. Results with the enthalpy-dependent table are found to predict the time-averaged flow field in terms of velocity, major species, and temperature with higher accuracy than in the adiabatic case. Further, they indicate, that heat losses should be accounted for to correctly predict the flame position. Subsequently, the thermo-chemical state variations over the thermo-acoustic cycle for the enthalpy-dependant case are analyzed in detail and compared with experimental data in terms of phase-conditioned averaged profiles and conditional averages. An overall good prediction is observed, although an overestimation of the oscillation amplitude yields a slight over-prediction of the velocity field in the low-pressure phases. The results provide a detailed quantitative analysis of the thermo-acoustic feedback mechanism of this burner.
{"title":"Numerical Investigation of the Local Thermo-Chemical State in a Thermo-Acoustically Unstable Dual Swirl Gas Turbine Model Combustor","authors":"T. J. P. Karpowski, F. Ferraro, M. Steinhausen, S. Popp, C. Arndt, Christian Kraus, H. Bockhorn, W. Meier, C. Hasse","doi":"10.1115/GT2022-83810","DOIUrl":"https://doi.org/10.1115/GT2022-83810","url":null,"abstract":"\u0000 In this work, the thermo-acoustic instabilities of a gas turbine model combustor, the so-called SFB606 combustor, are numerically investigated using Large Eddy Simulation (LES) combined with tabulated chemistry and Artificial Thickened Flame (ATF) approach. The main focus is a detailed analysis of the thermo-acoustic cycle and the accompanied equivalence ratio oscillations and their associated convective time delay. In particular, the variations of the thermo-chemical state and flame characteristics over the thermo-acoustic cycle are investigated. For the operating point flame B (Pth = 25kW, Φ = 0.7), the burner exhibits thermo-acoustic instabilities with a dominant frequency of 392 Hz, the acoustic eigenmode of the inner air inlet duct. These oscillations are accompanied by an equivalence ratio oscillation, which exhibits a convective time delay between the injection in the inner swirler and the flame zone. Two LES, one adiabatic and one accounting for heat losses at the walls by prescribing the wall temperatures from experimental data and Conjugated Heat Transfer (CHT) simulations, are conducted. Results with the enthalpy-dependent table are found to predict the time-averaged flow field in terms of velocity, major species, and temperature with higher accuracy than in the adiabatic case. Further, they indicate, that heat losses should be accounted for to correctly predict the flame position. Subsequently, the thermo-chemical state variations over the thermo-acoustic cycle for the enthalpy-dependant case are analyzed in detail and compared with experimental data in terms of phase-conditioned averaged profiles and conditional averages. An overall good prediction is observed, although an overestimation of the oscillation amplitude yields a slight over-prediction of the velocity field in the low-pressure phases. The results provide a detailed quantitative analysis of the thermo-acoustic feedback mechanism of this burner.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"20 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":"133138828","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}
D. Kroniger, Atsushi Horikawa, Kunio Okada, Yuji Ashida
A novel fuel injector is presented for enhancing the fuel flexibility of the dry micromix (MMX) combustion principle. Originally having been developed for pure hydrogen fueling, the micromix combustion is based on a non-premixed type jet-in-crossflow mixing for inherent safety against flashback, as well as flame miniaturization and multiplication for suppressing NOx emissions. This study investigates the potential of the novel geometry regarding the operation with higher natural gas content fuels. In experiments at atmospheric pressure conditions it could be shown that the new injector extends the fuel flexibility down to between 60 and 80 vol.% H2. The responsible flow phenomena are verified with numerical RANS simulations at engine pressure conditions using a detailed chemistry model. An experimental validation of numerical methods at atmospheric conditions based on OH chemiluminescence distributions showed that the unsteady LES model can predict the micromix flame more accurately regarding to its ignition point than the steady RANS model, although the reaction progress is underestimated by both models, which in comparison to the experiment results in a more stretched flame.
{"title":"Novel Fuel Injector Geometry for Enhancing the Fuel Flexibility of a Dry Low NOx MicroMix Flame","authors":"D. Kroniger, Atsushi Horikawa, Kunio Okada, Yuji Ashida","doi":"10.1115/gt2022-83025","DOIUrl":"https://doi.org/10.1115/gt2022-83025","url":null,"abstract":"\u0000 A novel fuel injector is presented for enhancing the fuel flexibility of the dry micromix (MMX) combustion principle. Originally having been developed for pure hydrogen fueling, the micromix combustion is based on a non-premixed type jet-in-crossflow mixing for inherent safety against flashback, as well as flame miniaturization and multiplication for suppressing NOx emissions. This study investigates the potential of the novel geometry regarding the operation with higher natural gas content fuels. In experiments at atmospheric pressure conditions it could be shown that the new injector extends the fuel flexibility down to between 60 and 80 vol.% H2. The responsible flow phenomena are verified with numerical RANS simulations at engine pressure conditions using a detailed chemistry model. An experimental validation of numerical methods at atmospheric conditions based on OH chemiluminescence distributions showed that the unsteady LES model can predict the micromix flame more accurately regarding to its ignition point than the steady RANS model, although the reaction progress is underestimated by both models, which in comparison to the experiment results in a more stretched flame.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"110 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":"121975469","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}
Megan F. Karalus, Dustin M. Brandt, L. McManus, E. Munktell
A modeling approach for quickly predicting Carbon Monoxide (CO) and Unburned Hydrocarbon (UHC) emissions is assessed in Simcenter STAR-CCM+ version 2021.3. Both magnitude and trends are evaluated across design variations of an aero-engine test combustor operating at an idle condition. Large Eddy Simulation (LES) is used with the non-iterative Pressure Implicit by Splitting of Operators (PISO) scheme, and the Flamelet Generated Manifold (FGM) combustion model. There are four geometric design variations of the same test combustor where changes are made to the dome effusion cooling, main swirler, and downstream orifices. These four geometries are chosen for this study because they yield distinctly different CO and UHC emissions, thus reducing signal to noise in assessing the predictive capability of the modeling approach. Sensitivity of the results to a key parameter in the liquid fuel spray breakup model is provided. By varying the breakup rate, the prediction of the CO emissions is shown to compare very favorably both in magnitude and trend to the experimentally measured values. The UHC emissions are shown to compare well for three of the four designs. Results are also generated using the Semi-Implicit Method for Pressure Linked Equations (SIMPLE) scheme; these show the same behavior as PISO. However, the results with PISO can be obtained between 2.5 and 3.5X faster than the more traditional approach. Combining the computational efficiency of FGM and PISO allows for fast and accurate predictions of regulated emissions, and therefore down-selection of designs earlier in the design process.
在Simcenter STAR-CCM+版本2021.3中评估了一种快速预测一氧化碳(CO)和未燃烧碳氢化合物(UHC)排放的建模方法。在空转条件下，对航空发动机测试燃烧室的设计变化进行了幅度和趋势评估。采用大涡模拟(LES)方法，结合非迭代的PISO (split of Operators)压力隐式方法和火焰生成歧管(FGM)燃烧模型。同一试验燃烧室有四种几何设计变化，其中对穹顶射流冷却，主旋流器和下游孔进行了改变。本研究选择这四种几何形状是因为它们产生明显不同的CO和UHC排放，从而在评估建模方法的预测能力时减少了信噪比。给出了结果对液体燃料喷雾破碎模型中一个关键参数的敏感性。通过改变分解速率，CO排放的预测结果在量级和趋势上都与实验测量值非常吻合。四种设计中有三种的UHC排放量比较好。结果也产生了半隐式方法的压力链接方程(SIMPLE)方案;它们表现出与PISO相同的行为。然而，使用PISO的结果可以比传统方法快2.5到3.5倍。结合FGM和PISO的计算效率，可以快速准确地预测受管制的排放，从而在设计过程的早期减少设计的选择。
{"title":"Predicting Emissions Across Design Variations of an Aero-Engine Combustor Using FGM and PISO","authors":"Megan F. Karalus, Dustin M. Brandt, L. McManus, E. Munktell","doi":"10.1115/gt2022-82291","DOIUrl":"https://doi.org/10.1115/gt2022-82291","url":null,"abstract":"\u0000 A modeling approach for quickly predicting Carbon Monoxide (CO) and Unburned Hydrocarbon (UHC) emissions is assessed in Simcenter STAR-CCM+ version 2021.3. Both magnitude and trends are evaluated across design variations of an aero-engine test combustor operating at an idle condition. Large Eddy Simulation (LES) is used with the non-iterative Pressure Implicit by Splitting of Operators (PISO) scheme, and the Flamelet Generated Manifold (FGM) combustion model. There are four geometric design variations of the same test combustor where changes are made to the dome effusion cooling, main swirler, and downstream orifices. These four geometries are chosen for this study because they yield distinctly different CO and UHC emissions, thus reducing signal to noise in assessing the predictive capability of the modeling approach. Sensitivity of the results to a key parameter in the liquid fuel spray breakup model is provided. By varying the breakup rate, the prediction of the CO emissions is shown to compare very favorably both in magnitude and trend to the experimentally measured values. The UHC emissions are shown to compare well for three of the four designs. Results are also generated using the Semi-Implicit Method for Pressure Linked Equations (SIMPLE) scheme; these show the same behavior as PISO. However, the results with PISO can be obtained between 2.5 and 3.5X faster than the more traditional approach. Combining the computational efficiency of FGM and PISO allows for fast and accurate predictions of regulated emissions, and therefore down-selection of designs earlier in the design process.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"8 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":"132976440","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}
Baha Suleiman, Hatem Selim, A. Dawood, A. Khalidi, V. K., J. Goldmeer, Kamal Al-Ahmadi, Ibrahim Al-Ghamdi, Eid Badr, Mohammed Al-Gahatani
Gas turbines operating on liquid fuels may produce higher NOx and soot emissions and may suffer from reduced combustion part durability, as compared to gas turbines operating on gaseous fuels. With some fuels, like diesel (aka light distillate), the NOx emissions increase is related to the liquid fuel spray atomization process, which plays a vital role in the combustion process. A promising technology for enhancing fuel atomization in a combustor is water-fuel emulsion technology. Injecting a water-fuel emulsion into a gas turbine combustor may lead to favorable effects. Since fuel atomization should be enhanced, combustion should occur at lower local equivalence ratio values, thus reducing the creation of NOx and soot emissions. Moreover, the presence of water in the combustion mixture decreases the average temperature of the combusting mixture due to the high latent heat of vaporization of water, which in turn should reduce NOx. In this study, a numerical investigation is conducted to quantify the impact of the water-fuel emulsion technology on gas turbine combustors operating on diesel fuel. The objective is to determine if NOx and soot emissions are improved, and if flame structure changes when the emulsion technology is utilized at different water to fuel ratios.
{"title":"Computational Investigation of Using Emulsified Fuels in Heavy Duty Gas Turbines","authors":"Baha Suleiman, Hatem Selim, A. Dawood, A. Khalidi, V. K., J. Goldmeer, Kamal Al-Ahmadi, Ibrahim Al-Ghamdi, Eid Badr, Mohammed Al-Gahatani","doi":"10.1115/gt2022-82184","DOIUrl":"https://doi.org/10.1115/gt2022-82184","url":null,"abstract":"\u0000 Gas turbines operating on liquid fuels may produce higher NOx and soot emissions and may suffer from reduced combustion part durability, as compared to gas turbines operating on gaseous fuels. With some fuels, like diesel (aka light distillate), the NOx emissions increase is related to the liquid fuel spray atomization process, which plays a vital role in the combustion process.\u0000 A promising technology for enhancing fuel atomization in a combustor is water-fuel emulsion technology. Injecting a water-fuel emulsion into a gas turbine combustor may lead to favorable effects. Since fuel atomization should be enhanced, combustion should occur at lower local equivalence ratio values, thus reducing the creation of NOx and soot emissions. Moreover, the presence of water in the combustion mixture decreases the average temperature of the combusting mixture due to the high latent heat of vaporization of water, which in turn should reduce NOx.\u0000 In this study, a numerical investigation is conducted to quantify the impact of the water-fuel emulsion technology on gas turbine combustors operating on diesel fuel. The objective is to determine if NOx and soot emissions are improved, and if flame structure changes when the emulsion technology is utilized at different water to fuel ratios.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"9 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":"123856675","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 study investigates two effects, which can lead to a mitigation of entropy waves in a gas turbine combustor: Mean flow shear dispersion and turbulent mixing. Using a transport equation for coherent fluctuations of a passive scalar in combination with a k-ε turbulence model, the advection and turbulent diffusion of entropy waves is modeled. The method is applied to a flow in a duct of rectangular cross section, previously investigated with experimental and numerical means by Weilenmann et al. [1]. We analyze the impact of a steady jet in crossflow (JIC) in the rectangular duct on the mitigation of entropy waves by the mean flow shear dispersion mechanism. First, a comparison to Large Eddy Simulation (LES) results demonstrates the capability of the linearized approach to quantify the decay due to turbulent mixing and mean flow shear dispersion. The results further indicate that the inhomogeneous highly three dimensional flow profile and increased turbulence caused by the JIC significantly mitigates entropy waves due to the enhancement of the mean flow shear dispersion and turbulent mixing in comparison to a base line configuration without the JIC. Second, we investigate in a parameter study the effect of turbulent mixing on the mitigation of the entropy waves. It is shown that the results are highly case dependent. While in some situations an increase in turbulent mixing — as expected — leads to a mitigation of entropy waves, in other situations it may have the opposite effect. We demonstrate that this is the case if turbulent mixing annihilates entropy fluctuations selectively in those regions, which contribute significantly to mean flow shear dispersion.
{"title":"Modeling the Convection of Entropy Waves in Strongly Non-Parallel Turbulent Flows Using a Linearized Framework","authors":"T. Kaiser, N. Noiray, Q. Malé, K. Oberleithner","doi":"10.1115/gt2022-82971","DOIUrl":"https://doi.org/10.1115/gt2022-82971","url":null,"abstract":"\u0000 The study investigates two effects, which can lead to a mitigation of entropy waves in a gas turbine combustor: Mean flow shear dispersion and turbulent mixing. Using a transport equation for coherent fluctuations of a passive scalar in combination with a k-ε turbulence model, the advection and turbulent diffusion of entropy waves is modeled. The method is applied to a flow in a duct of rectangular cross section, previously investigated with experimental and numerical means by Weilenmann et al. [1]. We analyze the impact of a steady jet in crossflow (JIC) in the rectangular duct on the mitigation of entropy waves by the mean flow shear dispersion mechanism. First, a comparison to Large Eddy Simulation (LES) results demonstrates the capability of the linearized approach to quantify the decay due to turbulent mixing and mean flow shear dispersion. The results further indicate that the inhomogeneous highly three dimensional flow profile and increased turbulence caused by the JIC significantly mitigates entropy waves due to the enhancement of the mean flow shear dispersion and turbulent mixing in comparison to a base line configuration without the JIC. Second, we investigate in a parameter study the effect of turbulent mixing on the mitigation of the entropy waves. It is shown that the results are highly case dependent. While in some situations an increase in turbulent mixing — as expected — leads to a mitigation of entropy waves, in other situations it may have the opposite effect. We demonstrate that this is the case if turbulent mixing annihilates entropy fluctuations selectively in those regions, which contribute significantly to mean flow shear dispersion.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"4 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":"115569417","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. D. De Giorgi, Ghazanfar Mehdi, S. Bonuso, M. Shamma, S. Harth, D. Trimis, N. Zarzalis
This study investigates the flame characterization near to lean blowout (LBO) limits at different pre-heating temperatures in lifted swirl methane-air plasma discharge stabilized flame. The combustor was equipped with a needle-ring type plasma actuator driven by a sinusoidal generator at 20 kHz directly coupled with methane-air premixed flame close to the injector exit. The needle electrode connected with high voltage (HV) and the nozzle acted as a grounded electrode. The electrical characterizations of combustion characteristics and LBO measurements have been carried out at different plasma power, air preheating temperatures, and air mass flow rates. Flame shape and intensity in the flame area have been analyzed based on the images acquired by using a high-resolution camera. Acoustic measurements were performed using high sensitivity microphone. Furthermore, post-processing of the microphone data involved the application of Fast Fourier Transform (FFT) and the wavelet decomposition to identify and characterize any periodic phenomena present in the system. It has been perceived that when the plasma is on, LBO limits were extended significantly. The maximum reduction of equivalence ratio at LBO was noticed in terms of percentage (79.4%) at 40% voltage amplitude, T = 373 K, and ma = 6 m3/h. Proper orthogonal decomposition was implemented on the high-speed chemiluminescence images and the frequency analysis of the time coefficients of the modes of the POD permits the identification of the dominant frequency ranges in the different operating conditions. The results were in good agreement with the findings of the FFT and Wavelet analysis on the microphone measured signals.
研究了不同预热温度下升力旋流甲烷-空气等离子体放电稳定火焰的近倾爆裂(LBO)极限火焰特性。燃烧室配备了一个针环式等离子体驱动器，由正弦发生器驱动，频率为20 kHz，与靠近喷射器出口的甲烷-空气预混火焰直接耦合。针电极与高压(HV)连接，喷嘴作为接地电极。在不同的等离子体功率、空气预热温度和空气质量流量下进行了燃烧特性和LBO测量的电学表征。利用高分辨率相机采集的图像，分析了火焰区域的火焰形状和强度。声学测量采用高灵敏度麦克风进行。此外，麦克风数据的后处理涉及快速傅里叶变换(FFT)和小波分解的应用，以识别和表征系统中存在的任何周期性现象。人们已经认识到，当等离子体打开时，杠杆收购限制显着延长。当电压幅值为40%，T = 373 K, ma = 6 m3/h时，LBO等效比的最大降幅为79.4%。对高速化学发光图像进行适当的正交分解，对POD各模态时间系数进行频率分析，识别出不同工况下的主导频率范围。结果与对麦克风测量信号进行FFT和小波分析的结果吻合较好。
{"title":"Characterization of Flame Behavior and Blowout Limits at Different Air Preheating Temperatures in Plasma Assisted Stabilized Combustor","authors":"M. D. De Giorgi, Ghazanfar Mehdi, S. Bonuso, M. Shamma, S. Harth, D. Trimis, N. Zarzalis","doi":"10.1115/gt2022-83239","DOIUrl":"https://doi.org/10.1115/gt2022-83239","url":null,"abstract":"\u0000 This study investigates the flame characterization near to lean blowout (LBO) limits at different pre-heating temperatures in lifted swirl methane-air plasma discharge stabilized flame. The combustor was equipped with a needle-ring type plasma actuator driven by a sinusoidal generator at 20 kHz directly coupled with methane-air premixed flame close to the injector exit. The needle electrode connected with high voltage (HV) and the nozzle acted as a grounded electrode. The electrical characterizations of combustion characteristics and LBO measurements have been carried out at different plasma power, air preheating temperatures, and air mass flow rates. Flame shape and intensity in the flame area have been analyzed based on the images acquired by using a high-resolution camera. Acoustic measurements were performed using high sensitivity microphone. Furthermore, post-processing of the microphone data involved the application of Fast Fourier Transform (FFT) and the wavelet decomposition to identify and characterize any periodic phenomena present in the system. It has been perceived that when the plasma is on, LBO limits were extended significantly. The maximum reduction of equivalence ratio at LBO was noticed in terms of percentage (79.4%) at 40% voltage amplitude, T = 373 K, and ma = 6 m3/h. Proper orthogonal decomposition was implemented on the high-speed chemiluminescence images and the frequency analysis of the time coefficients of the modes of the POD permits the identification of the dominant frequency ranges in the different operating conditions. The results were in good agreement with the findings of the FFT and Wavelet analysis on the microphone measured signals.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"203 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":"115274820","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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