Hydrogen from renewables or reformed natural gas with CO2 Capture and Storage (CCS) can be used as fuel to achieve CO2 free power production. Because of the challenges related to transport and storage of H2, NH3 has been proposed as a hydrogen carrier as it can be stored in liquid form at moderate pressures and temperatures. NH3 can be used as a fuel directly, but the low reactivity and flame speed in air makes combustion stability challenging in conventional gas turbine combustors. As no solutions are commercially available today, a transitional approach is to only replace part of the fuel with NH3 to limit the change in the combustion properties, although this only partly decarbonizes the fuel. This study investigates combustion of CH4/NH3 blends with air in a downscaled Dry Low Emission (DLE) burner at pressures up to 6 bar and thermal power up to 100 kW. The effects of equivalence ratio and NH3/CH4 mixture ratio on the emissions of NOx, CO, CH4, HCN, N2O, and NH3 are studied at different pressures and power. Even small amounts of NH3 introduction in the fuel results in unacceptable high NOx emissions in a conventional combustor and the flame stability limits the maximum NH3 content in the fuel. However, by using a two-stage combustion strategy with a rich primary zone, NOx emissions down to ca. 100 ppm could be achieved with a NH3 content up to 100%, provided the thermal intensity of the combustor is severely reduced.
{"title":"Experimental Study on Combustion of Methane / Ammonia Blends for Gas Turbine Application","authors":"M. Ditaranto, I. Saanum, J. Larfeldt","doi":"10.1115/gt2022-83039","DOIUrl":"https://doi.org/10.1115/gt2022-83039","url":null,"abstract":"\u0000 Hydrogen from renewables or reformed natural gas with CO2 Capture and Storage (CCS) can be used as fuel to achieve CO2 free power production. Because of the challenges related to transport and storage of H2, NH3 has been proposed as a hydrogen carrier as it can be stored in liquid form at moderate pressures and temperatures. NH3 can be used as a fuel directly, but the low reactivity and flame speed in air makes combustion stability challenging in conventional gas turbine combustors. As no solutions are commercially available today, a transitional approach is to only replace part of the fuel with NH3 to limit the change in the combustion properties, although this only partly decarbonizes the fuel. This study investigates combustion of CH4/NH3 blends with air in a downscaled Dry Low Emission (DLE) burner at pressures up to 6 bar and thermal power up to 100 kW. The effects of equivalence ratio and NH3/CH4 mixture ratio on the emissions of NOx, CO, CH4, HCN, N2O, and NH3 are studied at different pressures and power. Even small amounts of NH3 introduction in the fuel results in unacceptable high NOx emissions in a conventional combustor and the flame stability limits the maximum NH3 content in the fuel. However, by using a two-stage combustion strategy with a rich primary zone, NOx emissions down to ca. 100 ppm could be achieved with a NH3 content up to 100%, provided the thermal intensity of the combustor is severely reduced.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"42 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":"131260830","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}
Michael Pierro, Justin J Urso, Cory Kinney, Shubham Kesharwani, Jonathan McGaunn, Christopher W. Dennis, Subith S. Vasu
This study explores the combustion characterization of high-fuel percentage, air-diluted mixtures of H2 mixed with natural gas (NG) as well as mixtures of H2 and NH3 at temperatures and pressures relevant to turbine operating conditions (20–30 bar, 1000–1500 K). Lower temperatures (below 1070 K) exhibit preignition characteristics due to non-homogeneity. An attempt to mitigate these occurrences at high pressures is investigated using the constrained reaction volume (CRV) stage-filling technique. Due to the need to further refine the facility CRV stage-filling uncertainty, only higher temperature data will be interpreted at this time. The test conditions in this study closely replicate the temperatures, pressures, and mixtures that would be seen in hydrogen-powered gas turbines, making it the first to explore such conditions. The experimental IDTs were compared against the current state-of-the-art chemical kinetic models for mechanism validation. The current work will advance H2-powered turbines and aims to determine the optimum molecular ratio of H2 when mixed with natural gas.
本研究探讨了高燃料百分比、空气稀释的H2与天然气(NG)混合混合物以及H2和NH3混合物在与涡轮工作条件相关的温度和压力(20-30 bar, 1000-1500 K)下的燃烧特性。由于非均匀性，较低温度(低于1070 K)表现出预燃特性。为了在高压下减轻这些情况的发生，研究人员使用了受限反应体积(CRV)分段填充技术。由于需要进一步完善设施CRV级填充的不确定性，此时只能解释更高温度的数据。这项研究的测试条件与氢动力燃气轮机的温度、压力和混合物非常接近，这是第一次探索这种条件。实验IDTs与目前最先进的化学动力学模型进行了比较，以验证机理。目前的工作将推进H2动力涡轮机，并旨在确定H2与天然气混合时的最佳分子比。
{"title":"High-Fuel Loading Ignition Delay Time Characterization of Hydrogen/Natural Gas/Ammonia at Gas Turbine-Relevant Conditions Inside a High-Pressure Shock Tube","authors":"Michael Pierro, Justin J Urso, Cory Kinney, Shubham Kesharwani, Jonathan McGaunn, Christopher W. Dennis, Subith S. Vasu","doi":"10.1115/gt2022-82069","DOIUrl":"https://doi.org/10.1115/gt2022-82069","url":null,"abstract":"\u0000 This study explores the combustion characterization of high-fuel percentage, air-diluted mixtures of H2 mixed with natural gas (NG) as well as mixtures of H2 and NH3 at temperatures and pressures relevant to turbine operating conditions (20–30 bar, 1000–1500 K). Lower temperatures (below 1070 K) exhibit preignition characteristics due to non-homogeneity. An attempt to mitigate these occurrences at high pressures is investigated using the constrained reaction volume (CRV) stage-filling technique. Due to the need to further refine the facility CRV stage-filling uncertainty, only higher temperature data will be interpreted at this time. The test conditions in this study closely replicate the temperatures, pressures, and mixtures that would be seen in hydrogen-powered gas turbines, making it the first to explore such conditions. The experimental IDTs were compared against the current state-of-the-art chemical kinetic models for mechanism validation. The current work will advance H2-powered turbines and aims to determine the optimum molecular ratio of H2 when mixed with natural gas.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"318 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":"123687670","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}
Bernhard Ćosić, Dominik Wassmer, D. Kluß, Alexander Jaeschke, T. Reichel, C. Paschereit
Blending of natural gas with hydrogen is a viable pathway for the decarbonization of industrial gas turbines for combined heat and power applications. Very high blending ratios of hydrogen are needed to achieve significant CO2 emission reductions. However, burning high hydrogen contents in the gas turbine is challenging in terms of NOx emissions and the mitigation of flashback risks as well as suppressing thermoacoustic instabilities. This paper illustrates a design modification to improve the hydrogen capabilities of the Advanced Can Combustion (ACC) system and its ultra-low emission industrial swirl burner for the MGT6000 gas turbine that was originally designed for pure natural gas combustion. A flow conditioner is installed upstream of the swirler aiming to decrease the fuel amount close to the combustor walls and thereby increase the flashback resistance of the burner. High pressure (≈14bar) full power (≈4MWth) single can combustion tests and atmospheric burner tests are used for the assessment of the hydrogen capabilities for the original and the retrofitted burner. Different levels of hydrogen blending of up to 45 vol-% at high pressure and 93 vol-% at atmospheric conditions as well as different gas turbine relevant flame temperatures are assessed in terms of emissions, flame flashback and thermoacoustic stability. Low speed thermocouple measurements at the burner walls are identified as a good precursor for hydrogen induced flame flashback at the walls. The amplitude of the thermocouple fluctuation is observed to be similar for atmospheric and elevated pressure. Moreover, it is shown that the increase in NOx emissions associated to hydrogen blending can be transferred from atmospheric conditions to elevated pressure. The experimental dataset is used for the calibration of Computational Fluid Dynamics (CFD) calculations to allow for the assessment at different operating conditions and future modifications. The CFD is focused on the prediction of flashback resistance for different blends of hydrogen and natural gas at high pressure conditions.
{"title":"Experimental and Numerical Advancement of the MGT Combustor Towards Higher Hydrogen Capabilities","authors":"Bernhard Ćosić, Dominik Wassmer, D. Kluß, Alexander Jaeschke, T. Reichel, C. Paschereit","doi":"10.1115/gt2022-82110","DOIUrl":"https://doi.org/10.1115/gt2022-82110","url":null,"abstract":"\u0000 Blending of natural gas with hydrogen is a viable pathway for the decarbonization of industrial gas turbines for combined heat and power applications. Very high blending ratios of hydrogen are needed to achieve significant CO2 emission reductions. However, burning high hydrogen contents in the gas turbine is challenging in terms of NOx emissions and the mitigation of flashback risks as well as suppressing thermoacoustic instabilities. This paper illustrates a design modification to improve the hydrogen capabilities of the Advanced Can Combustion (ACC) system and its ultra-low emission industrial swirl burner for the MGT6000 gas turbine that was originally designed for pure natural gas combustion. A flow conditioner is installed upstream of the swirler aiming to decrease the fuel amount close to the combustor walls and thereby increase the flashback resistance of the burner. High pressure (≈14bar) full power (≈4MWth) single can combustion tests and atmospheric burner tests are used for the assessment of the hydrogen capabilities for the original and the retrofitted burner. Different levels of hydrogen blending of up to 45 vol-% at high pressure and 93 vol-% at atmospheric conditions as well as different gas turbine relevant flame temperatures are assessed in terms of emissions, flame flashback and thermoacoustic stability. Low speed thermocouple measurements at the burner walls are identified as a good precursor for hydrogen induced flame flashback at the walls. The amplitude of the thermocouple fluctuation is observed to be similar for atmospheric and elevated pressure. Moreover, it is shown that the increase in NOx emissions associated to hydrogen blending can be transferred from atmospheric conditions to elevated pressure. The experimental dataset is used for the calibration of Computational Fluid Dynamics (CFD) calculations to allow for the assessment at different operating conditions and future modifications. The CFD is focused on the prediction of flashback resistance for different blends of hydrogen and natural gas at high pressure conditions.","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":"114601402","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}
José Ramón Quiñonez Arce, G. Andrews, H. Phylaktou
The present work investigates one of the lowest NOx design concepts using directly fueled grid plate flame stabilisers [10] termed Grid Mix (GM). The work uses CFD to predict experimental results for the GM low NOx flame stabilisers operated with propane. An additional study was undertaken to analyse their performance on hydrogen, a zero-carbon fuel at the heart of the UK zero-carbon power generation policy. Combustors are in production using similar technology to GM, and at least two manufacturers have low NOx hydrogen combustors using similar flame stabilisers [9, 18, 21–24]. Also, as the tests were at atmospheric pressure, the results are relevant to process burners, and the test condition for the CFD was a 140 kW thermal input process burner. The Grid Mix technique for non-premixed combustion, with fuel injected into the airflow at the periphery of the air holes, allows rapid fuel and air mixing for lean non-premixed ultra-low NOx combustion. The technology has been investigated at high entry temperatures of modern industrial gas turbines with all the combustion air passing through the flame stabiliser at a typical reference Mach number for this condition of M = 0.047, at an overall pressure loss of ΔP/P = 2.4%, for a heat release of 28MW/m2. These conditions are well above most experimental and CFD publications on low NOx gas turbine emissions. The combustion and NOx predictions for hydrogen show that Grid Mix flame stabilisers offer a viable solution to low NOx with hydrogen combustors. In addition, the advantage of adding fuel and air mixing passage downstream of the Grid Mix fuel injector is also demonstrated, as used by Yorke et al. [18].
{"title":"FGM Applied to Grid Plate Flame Stabilisers for NOx Prediction in Non-Premixed Gas Turbine Combustion","authors":"José Ramón Quiñonez Arce, G. Andrews, H. Phylaktou","doi":"10.1115/gt2022-82150","DOIUrl":"https://doi.org/10.1115/gt2022-82150","url":null,"abstract":"The present work investigates one of the lowest NOx design concepts using directly fueled grid plate flame stabilisers [10] termed Grid Mix (GM). The work uses CFD to predict experimental results for the GM low NOx flame stabilisers operated with propane. An additional study was undertaken to analyse their performance on hydrogen, a zero-carbon fuel at the heart of the UK zero-carbon power generation policy. Combustors are in production using similar technology to GM, and at least two manufacturers have low NOx hydrogen combustors using similar flame stabilisers [9, 18, 21–24]. Also, as the tests were at atmospheric pressure, the results are relevant to process burners, and the test condition for the CFD was a 140 kW thermal input process burner.\u0000 The Grid Mix technique for non-premixed combustion, with fuel injected into the airflow at the periphery of the air holes, allows rapid fuel and air mixing for lean non-premixed ultra-low NOx combustion. The technology has been investigated at high entry temperatures of modern industrial gas turbines with all the combustion air passing through the flame stabiliser at a typical reference Mach number for this condition of M = 0.047, at an overall pressure loss of ΔP/P = 2.4%, for a heat release of 28MW/m2. These conditions are well above most experimental and CFD publications on low NOx gas turbine emissions.\u0000 The combustion and NOx predictions for hydrogen show that Grid Mix flame stabilisers offer a viable solution to low NOx with hydrogen combustors. In addition, the advantage of adding fuel and air mixing passage downstream of the Grid Mix fuel injector is also demonstrated, as used by Yorke et al. [18].","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"29 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":"115198450","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}
Joris Koomen, Tim Dammers, N. Demougeot, P. Stuttaford, J. Heinze, G. Stockhausen, Christian Fleing
Ensuring grid stability is becoming an increasingly large challenge as the amounts of power from new highly fluctuating sources like solar and wind are increasing. Fuel flexible gas turbines which can run on carbon free or low carbon fuels offer grid stability both on the basis of their inertia and the possibility to quickly ramp-up and down. A consortium led by Thomassen Energy is at work at realizing a cost-effective, ultra-low emissions (sub 9ppm NOx and CO) combustion system for gas turbines in the 1–300 MW output range. A key requirement is fuel flexibility and stable operation from 100% natural gas to 100% hydrogen and any mixture thereof. This paper describes the results of the second step in the testing cycle of the developed combustion technology. In this step the FlameSheet™ is validated at machine operating conditions. The tests are completed using a state-of-the-art test setup combined with novel optical analysis techniques. The results show that one of the developed hardware variants can run on a wide range of fuel compositions up to 100% hydrogen without flashback while emissions are below 9 ppm at 15% O2 dry conditions.
{"title":"High Pressure Testing With Optical Diagnostics of a Hydrogen Retrofit Solution to Eliminate Carbon Emissions","authors":"Joris Koomen, Tim Dammers, N. Demougeot, P. Stuttaford, J. Heinze, G. Stockhausen, Christian Fleing","doi":"10.1115/gt2022-82652","DOIUrl":"https://doi.org/10.1115/gt2022-82652","url":null,"abstract":"\u0000 Ensuring grid stability is becoming an increasingly large challenge as the amounts of power from new highly fluctuating sources like solar and wind are increasing. Fuel flexible gas turbines which can run on carbon free or low carbon fuels offer grid stability both on the basis of their inertia and the possibility to quickly ramp-up and down.\u0000 A consortium led by Thomassen Energy is at work at realizing a cost-effective, ultra-low emissions (sub 9ppm NOx and CO) combustion system for gas turbines in the 1–300 MW output range. A key requirement is fuel flexibility and stable operation from 100% natural gas to 100% hydrogen and any mixture thereof.\u0000 This paper describes the results of the second step in the testing cycle of the developed combustion technology. In this step the FlameSheet™ is validated at machine operating conditions. The tests are completed using a state-of-the-art test setup combined with novel optical analysis techniques.\u0000 The results show that one of the developed hardware variants can run on a wide range of fuel compositions up to 100% hydrogen without flashback while emissions are below 9 ppm at 15% O2 dry conditions.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"1 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":"128891872","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}
W. Krebs, Anatol Schulz, Benjamin Witzel, Cliff Johnson, W. Laster, J. Pent, R. Schilp, Samer Wasif, Adam M. Weaver
Under the international climate pact (Paris Agreement), participants agreed upon a framework to reduce greenhouse gas emissions and cap the rise in global temperatures at “well below” 2°C above pre-industrial levels by 2100, with 1.5°C being the ideal scenario. To meet this goal, the development of highly efficient power plants fired with natural gas or blends of natural gas and increased share of H2 is a central cornerstone to provide controllable electrical power generation. The new HL class addresses these needs by raising the combined cycle efficiency above 64% while offering high fuel flexibility with H2 blends up to 50% and significant turndown capability. The new HL class is equipped with the new ACE combustion system which was developed over the last decade, and which has been successfully tested in the SGT6-9000HL at Lincoln County (North Carolina, USA). The ACE combustion system is a can annular design which is equipped with a jet stabilized main burner piloted by a central swirl burner and an axial stage which is turned on at higher loads. The paper describes the combustion technologies applied to offer stability and low emissions over a large engine operation envelope and the associated development steps. Finally, test results from rig and engine testing are presented.
{"title":"Advanced Combustion System for High Efficiency (ACE) of the New SGT5/6- 9000HL Gas Turbine","authors":"W. Krebs, Anatol Schulz, Benjamin Witzel, Cliff Johnson, W. Laster, J. Pent, R. Schilp, Samer Wasif, Adam M. Weaver","doi":"10.1115/gt2022-82299","DOIUrl":"https://doi.org/10.1115/gt2022-82299","url":null,"abstract":"\u0000 Under the international climate pact (Paris Agreement), participants agreed upon a framework to reduce greenhouse gas emissions and cap the rise in global temperatures at “well below” 2°C above pre-industrial levels by 2100, with 1.5°C being the ideal scenario. To meet this goal, the development of highly efficient power plants fired with natural gas or blends of natural gas and increased share of H2 is a central cornerstone to provide controllable electrical power generation.\u0000 The new HL class addresses these needs by raising the combined cycle efficiency above 64% while offering high fuel flexibility with H2 blends up to 50% and significant turndown capability.\u0000 The new HL class is equipped with the new ACE combustion system which was developed over the last decade, and which has been successfully tested in the SGT6-9000HL at Lincoln County (North Carolina, USA). The ACE combustion system is a can annular design which is equipped with a jet stabilized main burner piloted by a central swirl burner and an axial stage which is turned on at higher loads. The paper describes the combustion technologies applied to offer stability and low emissions over a large engine operation envelope and the associated development steps. Finally, test results from rig and engine testing are presented.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"77 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":"115651671","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}
L. Langone, M. Amerighi, L. Mazzei, A. Andreini, Stefano Orsino, N. Ansari, Rakesh Yadav
The present work focuses on the numerical modeling through Large Eddy Simulations (LES) of a low-swirl partially premixed lean flame operated with gaseous fuel using a hybrid Thickened Flame (TF)-Flamelet Generated Manifolds (FGM) combustion model. This approach aims to overcome the challenges of modeling the flame lift-off in this burner and the stabilization of the reaction zone at a remarkable distance from the nozzle outlet section, for which the reproduction of finite rate effects on combustion physics is crucial. The underlying strategy consists of applying the artificial thickening to the scalar equations required for the query of the look-up table computed a priori. The mentioned combustion model has been implemented in a general-purpose commercial CFD solver and Non-Adiabatic Flamelets have been employed for the look-up table computation. The goal is to include a detailed chemistry description while maintaining a cost-effective approach and improving the reproduction of the turbulence-chemistry interaction. Results are validated with experimental data in terms of temperature and chemical species concentration maps, showing the potential of the coupled TF-FGM approach for describing this type of flame.
{"title":"Assessment of Thickened Flame Model Coupled With Flamelet Generated Manifold on a Low-Swirl Partially Premixed Gaseous Lifted Flame","authors":"L. Langone, M. Amerighi, L. Mazzei, A. Andreini, Stefano Orsino, N. Ansari, Rakesh Yadav","doi":"10.1115/gt2022-82122","DOIUrl":"https://doi.org/10.1115/gt2022-82122","url":null,"abstract":"\u0000 The present work focuses on the numerical modeling through Large Eddy Simulations (LES) of a low-swirl partially premixed lean flame operated with gaseous fuel using a hybrid Thickened Flame (TF)-Flamelet Generated Manifolds (FGM) combustion model. This approach aims to overcome the challenges of modeling the flame lift-off in this burner and the stabilization of the reaction zone at a remarkable distance from the nozzle outlet section, for which the reproduction of finite rate effects on combustion physics is crucial. The underlying strategy consists of applying the artificial thickening to the scalar equations required for the query of the look-up table computed a priori. The mentioned combustion model has been implemented in a general-purpose commercial CFD solver and Non-Adiabatic Flamelets have been employed for the look-up table computation. The goal is to include a detailed chemistry description while maintaining a cost-effective approach and improving the reproduction of the turbulence-chemistry interaction. Results are validated with experimental data in terms of temperature and chemical species concentration maps, showing the potential of the coupled TF-FGM approach for describing this type of flame.","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":"125778651","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}
Characterisation of autoignition risk is crucial for designing and optimising low-emission combustion systems as there is an increased demand for highly reactive and novel fuel mixtures. Achieving a residence time to prevent autoignition and obtaining an adequate mixing quality is a challenging trade-off for these fuels in lean-premixed combustion systems. The level of complexity increases further due to low-temperature chemical pathways and pressure-dependent reactions that strongly influence ignition delay at engine operating conditions. Detailed chemical kinetic mechanisms with hundreds of species and thousands of reactions are developed and employed to address this complexity and predict ignition delay accurately, especially for heavier hydrocarbons. However, direct implementation of these kinetic mechanisms is computationally prohibitive in high-fidelity CFD approaches such as large eddy simulation (LES) and stochastic simulation tools that require a large number of evaluations. Advanced stochastic methods are essential tools to quantify uncertainties due to the inherent variabilities in ambient, operating conditions and fuel composition on ignition delay time calculation for practical applications. This study introduces and implements a computationally efficient method based on metamodellig to predict ignition delay time over a wide range of operating conditions and fuel compositions for gas turbine combustion systems. A metamodel or surrogate model is an accurate and quick approximation of the original computational model based on a detailed chemical kinetic mechanism. Polynomial chaos expansion (PCE) as an advanced method is employed to build metamodels using a limited set of runs of the original ignition delay time model based on NUIGMech1.0 chemical kinetic mechanism as the most detailed and state-of-the-art chemical kinetic mechanism for natural gas. Developed metamodels for ignition delay time are valid over operating conditions of P = 20–40 bar and T = 700–900 K for natural gas containing C1 to C7 hydrocarbons at stoichiometric condition. These metamodels provide a fast, robust, and considerably accurate framework instead of a detailed chemical kinetic model that facilitates (a) characterising ignition delay time at different operating conditions and fuel compositions, (b) designing and optimising premixers and burners and (c) conducting uncertainty quantification and stochastic modelling studies.
随着对高活性和新型燃料混合物的需求不断增加，自燃风险的表征对于设计和优化低排放燃烧系统至关重要。实现停留时间，以防止自燃和获得适当的混合质量是一个具有挑战性的权衡这些燃料在稀预混燃烧系统。由于低温化学途径和压力依赖性反应对发动机工作条件下的点火延迟有很大影响，因此复杂性进一步增加。数百种物质和数千种反应的详细化学动力学机制被开发和应用，以解决这一复杂性，并准确预测点火延迟，特别是对于较重的碳氢化合物。然而，在需要大量评估的高保真CFD方法(如大涡模拟(LES)和随机模拟工具)中，直接实现这些动力学机制在计算上是禁止的。在实际应用中，先进的随机方法是量化由于环境、操作条件和燃料成分的内在变异性而导致的点火延迟时间计算中的不确定性的重要工具。本文介绍并实现了一种基于元建模的高效计算方法，用于燃气轮机燃烧系统在多种工况和燃料成分下的点火延迟时间预测。元模型或替代模型是基于详细的化学动力学机制的原始计算模型的精确和快速近似。采用多项式混沌展开(PCE)作为一种先进的方法，利用基于NUIGMech1.0化学动力学机理的原始点火延迟时间模型的有限运行集建立元模型，NUIGMech1.0化学动力学机理是目前最详细、最先进的天然气化学动力学机理。所建立的点火延迟时间元模型在P = 20 ~ 40 bar, T = 700 ~ 900 K的化学计量条件下对含C1 ~ C7烃的天然气是有效的。这些元模型提供了一个快速、稳健且相当准确的框架，而不是一个详细的化学动力学模型，它有助于(a)表征不同操作条件和燃料成分下的点火延迟时间，(b)设计和优化预混器和燃烧器，以及(c)进行不确定性量化和随机建模研究。
{"title":"Metamodelling of Ignition Delay Time for Natural Gas Blends Under Gas Turbine Operating Conditions","authors":"Sajjad Yousefian, G. Bourque, R. Monaghan","doi":"10.1115/gt2022-82269","DOIUrl":"https://doi.org/10.1115/gt2022-82269","url":null,"abstract":"\u0000 Characterisation of autoignition risk is crucial for designing and optimising low-emission combustion systems as there is an increased demand for highly reactive and novel fuel mixtures. Achieving a residence time to prevent autoignition and obtaining an adequate mixing quality is a challenging trade-off for these fuels in lean-premixed combustion systems. The level of complexity increases further due to low-temperature chemical pathways and pressure-dependent reactions that strongly influence ignition delay at engine operating conditions. Detailed chemical kinetic mechanisms with hundreds of species and thousands of reactions are developed and employed to address this complexity and predict ignition delay accurately, especially for heavier hydrocarbons. However, direct implementation of these kinetic mechanisms is computationally prohibitive in high-fidelity CFD approaches such as large eddy simulation (LES) and stochastic simulation tools that require a large number of evaluations. Advanced stochastic methods are essential tools to quantify uncertainties due to the inherent variabilities in ambient, operating conditions and fuel composition on ignition delay time calculation for practical applications. This study introduces and implements a computationally efficient method based on metamodellig to predict ignition delay time over a wide range of operating conditions and fuel compositions for gas turbine combustion systems. A metamodel or surrogate model is an accurate and quick approximation of the original computational model based on a detailed chemical kinetic mechanism. Polynomial chaos expansion (PCE) as an advanced method is employed to build metamodels using a limited set of runs of the original ignition delay time model based on NUIGMech1.0 chemical kinetic mechanism as the most detailed and state-of-the-art chemical kinetic mechanism for natural gas. Developed metamodels for ignition delay time are valid over operating conditions of P = 20–40 bar and T = 700–900 K for natural gas containing C1 to C7 hydrocarbons at stoichiometric condition. These metamodels provide a fast, robust, and considerably accurate framework instead of a detailed chemical kinetic model that facilitates (a) characterising ignition delay time at different operating conditions and fuel compositions, (b) designing and optimising premixers and burners and (c) conducting uncertainty quantification and stochastic modelling studies.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"81 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":"125884739","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}
G. Litrico, S. Shrivastava, E. Meeks, Pravin M. Nakod, Fang Xu, Dhanya T., Sivaprakasam Muthuraj
The altitude relight capability of an aero-engine is a critical requirement that defines the operational flight envelope of the engine. Regulatory requirements from the Federal Aviation Administration (FAA) and European Union Aviation Safety Agency (EASA) ask to establish the altitude and airspeed envelope for in-flight engine restarting and adherence to engine performance. Further, engine manufacturers are changing combustor designs to meet aggressive goals that limit the emission of nitrogen oxides (NOx). While these design changes help reduce the NOx formation, they can be problematic for restart capabilities at high altitudes. Therefore, the engine design process becomes a complex optimization problem with conflicting goals. Test-rig data can provide insights into the performance; however, using testing to explore the entire design space is challenging, expensive, and sometimes infeasible. In this scenario, high fidelity computational fluid dynamics (CFD) simulations can bridge this gap and are, therefore, widely evaluated by designers and simulation engineers. Such simulations need to resolve flow structures, spray distribution, and ignition processes to predict the high-altitude relight accurately. Moreover, no, or limited parameter adjustments should be required for correctly predicting the relight outcome across different operating conditions. In this work, numerical simulations are performed to predict an aviation gas-turbine combustor’s relight performance, operating under different conditions, including sea level and 40000 ft operation. The CFD simulations are performed using the unsteady RANS approach for turbulence, solution-adaptive meshing, and finite-rate kinetics for the combustion modeling that tracks the flame propagation during and after the spark event. The results are encouraging and predict accurate behavior of lighting and not lighting operating conditions consistent with the light/no-light outcomes from the experimental tests. The simulation methodology, best practices, and obtained results are discussed in this paper.
{"title":"Numerical Study of High-Altitude Relight for an Aviation Gas-Turbine Engine","authors":"G. Litrico, S. Shrivastava, E. Meeks, Pravin M. Nakod, Fang Xu, Dhanya T., Sivaprakasam Muthuraj","doi":"10.1115/gt2022-82951","DOIUrl":"https://doi.org/10.1115/gt2022-82951","url":null,"abstract":"\u0000 The altitude relight capability of an aero-engine is a critical requirement that defines the operational flight envelope of the engine. Regulatory requirements from the Federal Aviation Administration (FAA) and European Union Aviation Safety Agency (EASA) ask to establish the altitude and airspeed envelope for in-flight engine restarting and adherence to engine performance. Further, engine manufacturers are changing combustor designs to meet aggressive goals that limit the emission of nitrogen oxides (NOx). While these design changes help reduce the NOx formation, they can be problematic for restart capabilities at high altitudes. Therefore, the engine design process becomes a complex optimization problem with conflicting goals. Test-rig data can provide insights into the performance; however, using testing to explore the entire design space is challenging, expensive, and sometimes infeasible. In this scenario, high fidelity computational fluid dynamics (CFD) simulations can bridge this gap and are, therefore, widely evaluated by designers and simulation engineers. Such simulations need to resolve flow structures, spray distribution, and ignition processes to predict the high-altitude relight accurately. Moreover, no, or limited parameter adjustments should be required for correctly predicting the relight outcome across different operating conditions.\u0000 In this work, numerical simulations are performed to predict an aviation gas-turbine combustor’s relight performance, operating under different conditions, including sea level and 40000 ft operation. The CFD simulations are performed using the unsteady RANS approach for turbulence, solution-adaptive meshing, and finite-rate kinetics for the combustion modeling that tracks the flame propagation during and after the spark event. The results are encouraging and predict accurate behavior of lighting and not lighting operating conditions consistent with the light/no-light outcomes from the experimental tests. The simulation methodology, best practices, and obtained results are discussed in this paper.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"2 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":"117139579","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}
A. Gruber, Tarjei Heggset, Michael Duesing, Andrea Ciani
An increasing amount of recent experimental evidence indicates that sequential combustion is particularly well-suited for burning highly-reactive fuels like hydrogen, while maintaining low emissions. A convenient feature of the sequential combustion system, resulting in a fundamental advantage compared to alternative approaches, is the possibility of controlling the second-stage flame position through its combustion characteristics, defined by a complex balance of propagation versus spontaneous ignition, based mainly on the reactants’ inlet temperature. At full-load conditions, requiring high pressure and high flame temperature, fuel mixtures with a hydrogen content approaching 100% still bring significant challenges, it is therefore of key importance for the further development of hydrogen-firing capabilities of the gas turbine to improve our present understanding of the interaction between flame propagation and spontaneous ignition and of its role in controlling flame stability and emissions. A series of DNS and LES calculations, featuring complex chemical kinetics and a fully-compressible representation of the reactive flow, are performed on simplified geometrical configurations, yet representative of a sequential combustion system. The present research effort provides novel insight about the combustion characteristics of hydrogen reheat flames at nominal part- and full-load conditions, defining their structure and stabilization mechanism for a range of reactants temperature, as well as modelling guidelines for a reliable numerical approach to reheat combustion.
{"title":"A Numerical Investigation of Reheat Hydrogen Combustion in a Simplified Geometrical Configuration From Atmospheric Pressure to Full Load Conditions","authors":"A. Gruber, Tarjei Heggset, Michael Duesing, Andrea Ciani","doi":"10.1115/gt2022-83218","DOIUrl":"https://doi.org/10.1115/gt2022-83218","url":null,"abstract":"\u0000 An increasing amount of recent experimental evidence indicates that sequential combustion is particularly well-suited for burning highly-reactive fuels like hydrogen, while maintaining low emissions. A convenient feature of the sequential combustion system, resulting in a fundamental advantage compared to alternative approaches, is the possibility of controlling the second-stage flame position through its combustion characteristics, defined by a complex balance of propagation versus spontaneous ignition, based mainly on the reactants’ inlet temperature. At full-load conditions, requiring high pressure and high flame temperature, fuel mixtures with a hydrogen content approaching 100% still bring significant challenges, it is therefore of key importance for the further development of hydrogen-firing capabilities of the gas turbine to improve our present understanding of the interaction between flame propagation and spontaneous ignition and of its role in controlling flame stability and emissions. A series of DNS and LES calculations, featuring complex chemical kinetics and a fully-compressible representation of the reactive flow, are performed on simplified geometrical configurations, yet representative of a sequential combustion system. The present research effort provides novel insight about the combustion characteristics of hydrogen reheat flames at nominal part- and full-load conditions, defining their structure and stabilization mechanism for a range of reactants temperature, as well as modelling guidelines for a reliable numerical approach to reheat combustion.","PeriodicalId":395231,"journal":{"name":"Volume 3B: Combustion, Fuels, and Emissions","volume":"61 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":"132429478","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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