Niklas Petry, Manu Mannazhi, Zhiyao Yin, Oliver Lammel, Klaus Peter Geigle, Andreas Huber
Abstract In this work, a coaxial fuel nozzle was installed concentrically inside the outer air nozzle and was arranged in two different configurations. In the first, non-premixed case, the fuel and air nozzles were flush at the nozzle exit. In the second, partially premixed case, the fuel nozzle terminated 50 mm below the air nozzle exit. A third, fully premixed case was achieved by injecting fuel into an inline-mixer in the air 1 m upstream of the nozzle exit. Additionally, measurements were performed using fuel nozzles with two different sizes (inner diameters = 2 and 1.5 mm). For all these cases, percentage of hydrogen in the fuel was varied from 0 to 100 % (constant equivalence ratio, f = 0.74, thermal power Pth = 10.5 kW, jet exit velocity was kept at about vexit = 100 m/s at an air preheating Tpre = 300 K) and the resulting flames were characterized using 2D OH* chemiluminescence measurements. In addition, load-flexibility was investigated on the 100 % H2 case by varying the equivalence ratio (f = 0.74 to 0.21). Some selected conditions were further investigated using particle imaging velocimetry (PIV) to obtain velocity fields. The experimental results demonstrated a strong influence of nozzle configurations (mixedness), equivalence ratio and H2-content on flame shapes. Furhtermore, the results from this work are being used in a joint effort to validate numerical models for jet-stabilized hydrogen combustion.
{"title":"Investigation of Fuel and Load Flexibility of an Atmospheric Single Nozzle Jet-Stabilized FLOX® Combustor with Hydrogen/methane-Air Mixtures","authors":"Niklas Petry, Manu Mannazhi, Zhiyao Yin, Oliver Lammel, Klaus Peter Geigle, Andreas Huber","doi":"10.1115/1.4063782","DOIUrl":"https://doi.org/10.1115/1.4063782","url":null,"abstract":"Abstract In this work, a coaxial fuel nozzle was installed concentrically inside the outer air nozzle and was arranged in two different configurations. In the first, non-premixed case, the fuel and air nozzles were flush at the nozzle exit. In the second, partially premixed case, the fuel nozzle terminated 50 mm below the air nozzle exit. A third, fully premixed case was achieved by injecting fuel into an inline-mixer in the air 1 m upstream of the nozzle exit. Additionally, measurements were performed using fuel nozzles with two different sizes (inner diameters = 2 and 1.5 mm). For all these cases, percentage of hydrogen in the fuel was varied from 0 to 100 % (constant equivalence ratio, f = 0.74, thermal power Pth = 10.5 kW, jet exit velocity was kept at about vexit = 100 m/s at an air preheating Tpre = 300 K) and the resulting flames were characterized using 2D OH* chemiluminescence measurements. In addition, load-flexibility was investigated on the 100 % H2 case by varying the equivalence ratio (f = 0.74 to 0.21). Some selected conditions were further investigated using particle imaging velocimetry (PIV) to obtain velocity fields. The experimental results demonstrated a strong influence of nozzle configurations (mixedness), equivalence ratio and H2-content on flame shapes. Furhtermore, the results from this work are being used in a joint effort to validate numerical models for jet-stabilized hydrogen combustion.","PeriodicalId":15685,"journal":{"name":"Journal of Engineering for Gas Turbines and Power-transactions of The Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136116760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The following paper presents breakthrough experimental results for a new hermetic squeeze film damper (HSFD) concept that is integrally designed within an externally pressurized tilting-pad radial gas bearing support. The flexibly damped gas bearing module was designed for a 7.2" (183 mm) diameter shaft and fabricated using direct metal laser melting (DMLM); also known as additive manufacturing. The bearing and HSFD were sized based on ongoing studies for oil-free super-critical carbon dioxide (sCO2) power turbines in the 8.5MW-10MW power range. The development of the new damper concept was motivated by past dynamic testing on HSFD, which generated frequency dependent stiffness and damping force coefficients. In efforts to eliminate the frequency dependency, a new HSFD architecture was conceived that adds accumulator volumes and a pass-through channel to previously conceived HSFD flow network designs. The other motivation of the work is the need for developing a cost-effective and reliable oil-free bearing technology that is scalable to large power turbomachinery applications. There were several objectives to the following work. The first objective was to successfully design and fabricate a single piece bearing-damper using additive manufacturing, while dimensionally controlling critical design features. The paper discusses the manufacturing steps and shows cut-ups that reveal adequate clearance control capability with internal damper clearances.
{"title":"Identification of Dynamic Force Coefficients for an Additively Manufactured Hermetic Squeeze Film Bearing Support Damper Utilizing a Pass-Through Channel","authors":"Bugra Ertas, Keith Gary, Thomas Adcock","doi":"10.1115/1.4063781","DOIUrl":"https://doi.org/10.1115/1.4063781","url":null,"abstract":"Abstract The following paper presents breakthrough experimental results for a new hermetic squeeze film damper (HSFD) concept that is integrally designed within an externally pressurized tilting-pad radial gas bearing support. The flexibly damped gas bearing module was designed for a 7.2\" (183 mm) diameter shaft and fabricated using direct metal laser melting (DMLM); also known as additive manufacturing. The bearing and HSFD were sized based on ongoing studies for oil-free super-critical carbon dioxide (sCO2) power turbines in the 8.5MW-10MW power range. The development of the new damper concept was motivated by past dynamic testing on HSFD, which generated frequency dependent stiffness and damping force coefficients. In efforts to eliminate the frequency dependency, a new HSFD architecture was conceived that adds accumulator volumes and a pass-through channel to previously conceived HSFD flow network designs. The other motivation of the work is the need for developing a cost-effective and reliable oil-free bearing technology that is scalable to large power turbomachinery applications. There were several objectives to the following work. The first objective was to successfully design and fabricate a single piece bearing-damper using additive manufacturing, while dimensionally controlling critical design features. The paper discusses the manufacturing steps and shows cut-ups that reveal adequate clearance control capability with internal damper clearances.","PeriodicalId":15685,"journal":{"name":"Journal of Engineering for Gas Turbines and Power-transactions of The Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135804161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract This work presents the techno-economic analysis of the Solid oxide semi-closed CO2 cycle (SOS-CO2), a hybrid semiclosed cycle with solid oxide fuel cells (SOFC) recently developed by Politecnico di Milano for power generation from natural gas with near-zero CO2 emissions. The cycle is able to achieve an outstanding net electric efficiency of 75.7%, capturing more than 99% of the generated CO2. All the cycles components have been designed and sized with the aim of assessing performance and capital cost. Performance and economic key performance indicators are compared with those of two benchmark technologies for power generation with CO2 capture: the Allam cycle and a combined cycle equipped with ammines for post-combustion capture. Moreover, a sensitivity analysis is performed on the forecasted cost of natural gas and SOFC stacks. The results indicate that the specific total capital requirement of the SOS-CO2 cycle (2.52k€/kWel) is considerably higher than the Allam cycle (1.93 k€/kWel) and combined cycle with post-combustion capture (1.98 k€/kWel). On the other hand, the SOS-CO2 cycle benefits from its far higher efficiency (73.3% vs. 53.9% of the Allam cycle and 52.8% of the combined cycle) which makes the cycle less sensitive to the fuel cost and CO2 tax. In terms of cost of electricity, the SOS-CO2 cycle results the best technology for natural gas prices above 8 €/GJ, while the Allam cycle appears to be the preferred option at lower prices.
{"title":"Techno-Economic Analysis of the Solid Oxide Semi-Closed CO2 Cycle and Comparison with Other Power Generation Cycles with CO2 Capture","authors":"Matteo Martinelli, Roberto Scaccabarozzi, Manuele Gatti, Stefano Campanari, Emanuele Martelli","doi":"10.1115/1.4063740","DOIUrl":"https://doi.org/10.1115/1.4063740","url":null,"abstract":"Abstract This work presents the techno-economic analysis of the Solid oxide semi-closed CO2 cycle (SOS-CO2), a hybrid semiclosed cycle with solid oxide fuel cells (SOFC) recently developed by Politecnico di Milano for power generation from natural gas with near-zero CO2 emissions. The cycle is able to achieve an outstanding net electric efficiency of 75.7%, capturing more than 99% of the generated CO2. All the cycles components have been designed and sized with the aim of assessing performance and capital cost. Performance and economic key performance indicators are compared with those of two benchmark technologies for power generation with CO2 capture: the Allam cycle and a combined cycle equipped with ammines for post-combustion capture. Moreover, a sensitivity analysis is performed on the forecasted cost of natural gas and SOFC stacks. The results indicate that the specific total capital requirement of the SOS-CO2 cycle (2.52k€/kWel) is considerably higher than the Allam cycle (1.93 k€/kWel) and combined cycle with post-combustion capture (1.98 k€/kWel). On the other hand, the SOS-CO2 cycle benefits from its far higher efficiency (73.3% vs. 53.9% of the Allam cycle and 52.8% of the combined cycle) which makes the cycle less sensitive to the fuel cost and CO2 tax. In terms of cost of electricity, the SOS-CO2 cycle results the best technology for natural gas prices above 8 €/GJ, while the Allam cycle appears to be the preferred option at lower prices.","PeriodicalId":15685,"journal":{"name":"Journal of Engineering for Gas Turbines and Power-transactions of The Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135917932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tomasz Matuschek, Tom Otten, Sebastian Zenkner, Richard-Gregor Becker, Jacopo Zamboni, Erwin Moerland
Abstract The design of supersonic military aircraft is a complex multidisciplinary optimization (MDO) process in which the dependencies and strong interactions between engine and aircraft must be imperatively considered. Applying a fully coupled propulsion-airframe design system is a highly challenging task, since it requires a set of numerically stable analysis tools capable of optimizing multiple design variables simultaneously. To improve computational efficiency, the application of low-fidelity design of experiment (DOE) methods aid in narrowing down the selection of suitable combinations of design parameters. This approach allows the division of the multidisciplinary process into subsystems, each of which can be served by specialized engineers. Interactions between the disciplines are then considered by exchanging DOE-based sensitivities. This paper presents the multidisciplinary design process developed at the German Aerospace Center (DLR), - in which the airframe and propulsion system are designed simultaneously whilst effectively utilizing DOE-based sensitivities. Guiding the work is an application case on the preliminary design of military engine concepts considering its effects on overall integrated aircraft architecture. The design process is used to investigate the influence of important engine parameters such as overall pressure ratio (OPR), bypass ratio (BPR) and turbine entry temperature (T4) on the design of military aircraft. Furthermore, the impacts of thrust requirements and technological constraints of the engine are analyzed
{"title":"Application of a Multidisciplinary Design Process to Assess the Influence of Requirements and Constraints On the Design of Military Engines","authors":"Tomasz Matuschek, Tom Otten, Sebastian Zenkner, Richard-Gregor Becker, Jacopo Zamboni, Erwin Moerland","doi":"10.1115/1.4063742","DOIUrl":"https://doi.org/10.1115/1.4063742","url":null,"abstract":"Abstract The design of supersonic military aircraft is a complex multidisciplinary optimization (MDO) process in which the dependencies and strong interactions between engine and aircraft must be imperatively considered. Applying a fully coupled propulsion-airframe design system is a highly challenging task, since it requires a set of numerically stable analysis tools capable of optimizing multiple design variables simultaneously. To improve computational efficiency, the application of low-fidelity design of experiment (DOE) methods aid in narrowing down the selection of suitable combinations of design parameters. This approach allows the division of the multidisciplinary process into subsystems, each of which can be served by specialized engineers. Interactions between the disciplines are then considered by exchanging DOE-based sensitivities. This paper presents the multidisciplinary design process developed at the German Aerospace Center (DLR), - in which the airframe and propulsion system are designed simultaneously whilst effectively utilizing DOE-based sensitivities. Guiding the work is an application case on the preliminary design of military engine concepts considering its effects on overall integrated aircraft architecture. The design process is used to investigate the influence of important engine parameters such as overall pressure ratio (OPR), bypass ratio (BPR) and turbine entry temperature (T4) on the design of military aircraft. Furthermore, the impacts of thrust requirements and technological constraints of the engine are analyzed","PeriodicalId":15685,"journal":{"name":"Journal of Engineering for Gas Turbines and Power-transactions of The Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135918244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Leo C. C. Mesquita, Aymeric Vié, Sébastien Ducruix
Abstract The BIMER combustor is a lab-scale burner investigating fuel staging techniques as a stabilisation strategy for lean premixed prevaporized combustion for aeronautical applications. Two stages compose its injection system: the pilot and the multipoint stages. The staging factor is defined as the ratio of fuel mass flow rate injected through the pilot stage over the total one. As three flame shapes were found experimentally, Large-Eddy Simulations are performed in this study to assess the impact of the flame shape on the combustion regime and stability of the burner. Two operating conditions were explored experimentally (pilot-only and multipoint-dominated) to validate the simulations and compare the three flames. An additional multipoint-only condition is also investigated for the V flame. The burning regimes (premixed and non-premixed) and noise signatures (as a function of fuel staging) were compared to check whether these flames could benefit from the staging strategy. The M and Tulip flame combustion regimes are little affected by fuel staging, remaining mostly premixed and non-premixed, respectively, regardless of fuel staging. In opposition, the V flame changes from being mostly non-premixed to completely premixed when the injection is changed from pilot-only to multipoint-only. For the same staging evolution, the V flame also emits less noise for the investigated points. These results show that the V flame shape is the only one that allows this burner to benefit from an efficient fuel staging strategy.
{"title":"Numerical Analysis of Flame Shape Impact On the Performance of Fuel Staging in a Lean-Burn Aeronautical Burner","authors":"Leo C. C. Mesquita, Aymeric Vié, Sébastien Ducruix","doi":"10.1115/1.4063741","DOIUrl":"https://doi.org/10.1115/1.4063741","url":null,"abstract":"Abstract The BIMER combustor is a lab-scale burner investigating fuel staging techniques as a stabilisation strategy for lean premixed prevaporized combustion for aeronautical applications. Two stages compose its injection system: the pilot and the multipoint stages. The staging factor is defined as the ratio of fuel mass flow rate injected through the pilot stage over the total one. As three flame shapes were found experimentally, Large-Eddy Simulations are performed in this study to assess the impact of the flame shape on the combustion regime and stability of the burner. Two operating conditions were explored experimentally (pilot-only and multipoint-dominated) to validate the simulations and compare the three flames. An additional multipoint-only condition is also investigated for the V flame. The burning regimes (premixed and non-premixed) and noise signatures (as a function of fuel staging) were compared to check whether these flames could benefit from the staging strategy. The M and Tulip flame combustion regimes are little affected by fuel staging, remaining mostly premixed and non-premixed, respectively, regardless of fuel staging. In opposition, the V flame changes from being mostly non-premixed to completely premixed when the injection is changed from pilot-only to multipoint-only. For the same staging evolution, the V flame also emits less noise for the investigated points. These results show that the V flame shape is the only one that allows this burner to benefit from an efficient fuel staging strategy.","PeriodicalId":15685,"journal":{"name":"Journal of Engineering for Gas Turbines and Power-transactions of The Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135855640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract If pure hydrogen is used as a fuel in high-temperature fuel cells, waste heat must be removed by air cooling, which requires increased power consumption for supplying excess air. This study presents a hydrogen-fed solid oxide fuel cell (SOFC) that uses water instead of air for stack cooling and improved system performance. A novel SOFC system with energy cascade utilization is also proposed using cooling water as the working fluid for a steam turbine. Water cooling for the SOFC stack cooling reduced the stack power and efficiency but significantly reduced the power consumption for supplying excess air by more than 60%. Under ambient SOFC operating pressure, the net power and efficiency of the proposed system were increased by 25.6% and 12.2%p compared to the air-cooled system, respectively. At an SOFC operating pressure of 1000 kPa, the proposed hybrid system with energy cascade utilization achieved improvements of 10.2% in net power and 7.5%p in net efficiency, leading to efficiency higher than 73%. This study is significant in that it proposes a novel high-efficiency SOFC system with energy cascade utilization by using two-phase water as a cooling medium and working fluid of steam turbine.
{"title":"Evaluation of Water-Cooling Effect in Hydrogen-Fed SOFC for High-Efficiency Combined System Design","authors":"Hye Rim Kim, Tong Seop Kim","doi":"10.1115/1.4063743","DOIUrl":"https://doi.org/10.1115/1.4063743","url":null,"abstract":"Abstract If pure hydrogen is used as a fuel in high-temperature fuel cells, waste heat must be removed by air cooling, which requires increased power consumption for supplying excess air. This study presents a hydrogen-fed solid oxide fuel cell (SOFC) that uses water instead of air for stack cooling and improved system performance. A novel SOFC system with energy cascade utilization is also proposed using cooling water as the working fluid for a steam turbine. Water cooling for the SOFC stack cooling reduced the stack power and efficiency but significantly reduced the power consumption for supplying excess air by more than 60%. Under ambient SOFC operating pressure, the net power and efficiency of the proposed system were increased by 25.6% and 12.2%p compared to the air-cooled system, respectively. At an SOFC operating pressure of 1000 kPa, the proposed hybrid system with energy cascade utilization achieved improvements of 10.2% in net power and 7.5%p in net efficiency, leading to efficiency higher than 73%. This study is significant in that it proposes a novel high-efficiency SOFC system with energy cascade utilization by using two-phase water as a cooling medium and working fluid of steam turbine.","PeriodicalId":15685,"journal":{"name":"Journal of Engineering for Gas Turbines and Power-transactions of The Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135918681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Electrified Aircraft Propulsion (EAP) holds great potential for reducing aviation emissions and fuel burn. A variety of EAP architectures have been proposed including partially-turboelectric configurations that combine turbofan engines with motor-driven propulsors. Such architectures exhibit coupling between subsystems and thus require an integrated control solution. This paper presents an integrated control design strategy for a commercial single-aisle partially-turboelectric aircraft concept consisting of two wing-mounted turbofan engines and an electric motor driven tailfan propulsor. The turbofans serve the dual purpose of generating thrust and supplying mechanical offtake power used to generate electricity for the tailfan motor. The propulsion control system is tasked with coordinating turbofan and tailfan operation under both steady-state and transient scenarios. The paper introduces a linear state-space representation of the architecture reflecting the coupling between the turbofan and tailfan subsystems along with loop transfer functions reflecting open- and closed-loop system dynamics. Also discussed is an applied strategy for scheduling the tailfan setpoint command based on the average sensed fan speed of the two turbofans. This approach ensures synchronized operation of the turbofan and tailfan subsystems while also allowing the turbofan fuel control design to be simplified. Performance of the integrated control design is assessed through a real-time hardware-in-the-loop test. Results from this facility test are presented to illustrate the efficacy of the applied integrated control design approach under steady-state and transient scenarios.
{"title":"Integrated Control Design for a Partially Turboelectric Aircraft Propulsion System","authors":"Donald L Simon, Santino J. Bianco, Marcus Horning","doi":"10.1115/1.4063715","DOIUrl":"https://doi.org/10.1115/1.4063715","url":null,"abstract":"Abstract Electrified Aircraft Propulsion (EAP) holds great potential for reducing aviation emissions and fuel burn. A variety of EAP architectures have been proposed including partially-turboelectric configurations that combine turbofan engines with motor-driven propulsors. Such architectures exhibit coupling between subsystems and thus require an integrated control solution. This paper presents an integrated control design strategy for a commercial single-aisle partially-turboelectric aircraft concept consisting of two wing-mounted turbofan engines and an electric motor driven tailfan propulsor. The turbofans serve the dual purpose of generating thrust and supplying mechanical offtake power used to generate electricity for the tailfan motor. The propulsion control system is tasked with coordinating turbofan and tailfan operation under both steady-state and transient scenarios. The paper introduces a linear state-space representation of the architecture reflecting the coupling between the turbofan and tailfan subsystems along with loop transfer functions reflecting open- and closed-loop system dynamics. Also discussed is an applied strategy for scheduling the tailfan setpoint command based on the average sensed fan speed of the two turbofans. This approach ensures synchronized operation of the turbofan and tailfan subsystems while also allowing the turbofan fuel control design to be simplified. Performance of the integrated control design is assessed through a real-time hardware-in-the-loop test. Results from this facility test are presented to illustrate the efficacy of the applied integrated control design approach under steady-state and transient scenarios.","PeriodicalId":15685,"journal":{"name":"Journal of Engineering for Gas Turbines and Power-transactions of The Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136097371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Isacco Rafanelli, Giulio Generini, Antonio Andreini, Tommaso Diurno, Gabriele Girezzi, Andrea Paggini
Abstract Carbon Dioxide at supercritical state shows favorable thermodynamic properties for closed loop Brayton and Rankine cycles. High density, close to a liquid, and low viscosity, close to a gas, drive to achieve higher energy conversion efficiency with smaller size turbines and components. DGSs are gas-lubricated, noncontacting, endface seals, consisting of a mating (rotating) ring and a primary (stationary) ring. Due to high rotational speeds, small size sealing gaps, high fluid pressure and density, the heat generated by friction through the seal has a large impact on the temperature distribution, therefore a thermal design is needed to stay below the seal allowable temperature. Nowadays, numerical Conjugate Heat Transfer (CHT) analysis is a good industrial practice to quantify the thermal distribution in turbomachinery components. On the other hand, due to different order of magnitude of secondary flows cavity sizes and DGS seal gaps, simulating the whole fluid domain with 3D Computational Fluid Dynamic (CFD) calculation could drive to prohibitive computational costs. This paper presents a fast numerical iterative procedure based on a commercial 1D flow network modeler (Altair Flow Simulator) coupled with a commercial finite element solver (Ansys Mechanical). The proposed procedure is applied and validated in a DGS test bench operated by Flowserve. Validation data set has been generated operating the DGS in the test bench at different conditions in terms of angular velocity and housing temperature with sCO2 as working fluid. Results have shown a good agreement with experimental data at each operating condition with extremely low computational times.
{"title":"Development and Validation of a Segregated Conjugate Heat Transfer Procedure On a sCO2 Dry Gas Seal Test Bench","authors":"Isacco Rafanelli, Giulio Generini, Antonio Andreini, Tommaso Diurno, Gabriele Girezzi, Andrea Paggini","doi":"10.1115/1.4063716","DOIUrl":"https://doi.org/10.1115/1.4063716","url":null,"abstract":"Abstract Carbon Dioxide at supercritical state shows favorable thermodynamic properties for closed loop Brayton and Rankine cycles. High density, close to a liquid, and low viscosity, close to a gas, drive to achieve higher energy conversion efficiency with smaller size turbines and components. DGSs are gas-lubricated, noncontacting, endface seals, consisting of a mating (rotating) ring and a primary (stationary) ring. Due to high rotational speeds, small size sealing gaps, high fluid pressure and density, the heat generated by friction through the seal has a large impact on the temperature distribution, therefore a thermal design is needed to stay below the seal allowable temperature. Nowadays, numerical Conjugate Heat Transfer (CHT) analysis is a good industrial practice to quantify the thermal distribution in turbomachinery components. On the other hand, due to different order of magnitude of secondary flows cavity sizes and DGS seal gaps, simulating the whole fluid domain with 3D Computational Fluid Dynamic (CFD) calculation could drive to prohibitive computational costs. This paper presents a fast numerical iterative procedure based on a commercial 1D flow network modeler (Altair Flow Simulator) coupled with a commercial finite element solver (Ansys Mechanical). The proposed procedure is applied and validated in a DGS test bench operated by Flowserve. Validation data set has been generated operating the DGS in the test bench at different conditions in terms of angular velocity and housing temperature with sCO2 as working fluid. Results have shown a good agreement with experimental data at each operating condition with extremely low computational times.","PeriodicalId":15685,"journal":{"name":"Journal of Engineering for Gas Turbines and Power-transactions of The Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136098343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Rotating detonation combustors (RDC) have gained increased interest for integration with power-generating gas turbines due to the potential to increase thermal efficiency. The unsteady flow field exiting the RDC is fundamentally different compared to traditional swirl-stabilized combustors. Successful integration of RDC with gas turbines will depend on the ability to properly condition the unsteady flow to achieve performance levels comparable to swirl-stabilized combustors. RDC simulations require significant computational resources due to the small spatial and temporal time scales required to resolve the detonation phenomenon. Furthermore, traditional steady-state computational fluid dynamics (CFD) analyses are not possible for RDC simulations. The present study develops and validates a computationally efficient approach for predicting unsteady flow fields exiting the combustor using 2D, transient reacting CFD with periodic boundary conditions in the combustor and a downstream plenum. Validation is performed by comparing the CFD results to various experimental measurements: i) wave speed obtained from high-speed ion probe and dynamic pressure data, ii) average wall static pressure measurements, and iii) time-resolved particle image velocimetry (PIV) at 100 kHz at the RDC exit. Results indicate good agreement between CFD and experiments with respect to velocity field exiting the RDC, detonation wave speed, and static pressure distribution.
{"title":"Validation of Rotating Detonation Combustor CFD for Predicting Unsteady Supersonic-Subsonic Flow Field At the Exit","authors":"Piyush Raj, Shaon Talukdar, Dalton Langner, Apurav Gupta, Joseph Meadows, Ajay Agrawal","doi":"10.1115/1.4063706","DOIUrl":"https://doi.org/10.1115/1.4063706","url":null,"abstract":"Abstract Rotating detonation combustors (RDC) have gained increased interest for integration with power-generating gas turbines due to the potential to increase thermal efficiency. The unsteady flow field exiting the RDC is fundamentally different compared to traditional swirl-stabilized combustors. Successful integration of RDC with gas turbines will depend on the ability to properly condition the unsteady flow to achieve performance levels comparable to swirl-stabilized combustors. RDC simulations require significant computational resources due to the small spatial and temporal time scales required to resolve the detonation phenomenon. Furthermore, traditional steady-state computational fluid dynamics (CFD) analyses are not possible for RDC simulations. The present study develops and validates a computationally efficient approach for predicting unsteady flow fields exiting the combustor using 2D, transient reacting CFD with periodic boundary conditions in the combustor and a downstream plenum. Validation is performed by comparing the CFD results to various experimental measurements: i) wave speed obtained from high-speed ion probe and dynamic pressure data, ii) average wall static pressure measurements, and iii) time-resolved particle image velocimetry (PIV) at 100 kHz at the RDC exit. Results indicate good agreement between CFD and experiments with respect to velocity field exiting the RDC, detonation wave speed, and static pressure distribution.","PeriodicalId":15685,"journal":{"name":"Journal of Engineering for Gas Turbines and Power-transactions of The Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136210565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Soichiro Tabata, Kiyoshi Segawa, Tadashi Takahashi, Jin Aoyagi
Abstract This study focused on the expansion rate of steam; the effect on efficiency was investigated experimentally and numerically by varying the expansion rate of steam in the stage where condensation occurs by varying the flow rate and inlet temperature using a five-stage model steam turbine. The steam expansion rate of the stator blades in each stage was evaluated from the measured wall pressure and total pressure. In addition, the turbine efficiency was evaluated from the measured torque and mass flow rate, and the effect of flow rate and condensing stage can be taken into account for losses caused by condensation. In addition, numerical calculations to account for the effects of non-equilibrium condensation were performed using ANSYS CFX. The numerical calculations were able to show the details of the nucleation situation and the resulting changes in flow patterns. Numerical evaluation of the subcooling loss showed that there was no difference in subcooling loss between different mass flow rates. The steam expansion rate was evaluated from the measurement results, and it was found that there was no difference in the steam expansion rate due to differences in mass flow rate. This corresponds to the numerical result that the subcooling loss does not vary with flow rate.
{"title":"Experimental and Numerical Investigations of Steam Expansion Rate in Low Pressure Steam Turbine","authors":"Soichiro Tabata, Kiyoshi Segawa, Tadashi Takahashi, Jin Aoyagi","doi":"10.1115/1.4063711","DOIUrl":"https://doi.org/10.1115/1.4063711","url":null,"abstract":"Abstract This study focused on the expansion rate of steam; the effect on efficiency was investigated experimentally and numerically by varying the expansion rate of steam in the stage where condensation occurs by varying the flow rate and inlet temperature using a five-stage model steam turbine. The steam expansion rate of the stator blades in each stage was evaluated from the measured wall pressure and total pressure. In addition, the turbine efficiency was evaluated from the measured torque and mass flow rate, and the effect of flow rate and condensing stage can be taken into account for losses caused by condensation. In addition, numerical calculations to account for the effects of non-equilibrium condensation were performed using ANSYS CFX. The numerical calculations were able to show the details of the nucleation situation and the resulting changes in flow patterns. Numerical evaluation of the subcooling loss showed that there was no difference in subcooling loss between different mass flow rates. The steam expansion rate was evaluated from the measurement results, and it was found that there was no difference in the steam expansion rate due to differences in mass flow rate. This corresponds to the numerical result that the subcooling loss does not vary with flow rate.","PeriodicalId":15685,"journal":{"name":"Journal of Engineering for Gas Turbines and Power-transactions of The Asme","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136211405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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