Lorenzo Orsini, Alessio Picchi, Bruno Facchini, Alessio Bonini, Luca Innocenti
Abstract The rim seals of gas turbines are used to control the ingestion of hot mainstream gas into the wheel space between the rotor disk and the stationary casing. Sealing air, which is generally used to pressurize the cavity space, flows through the seal clearance and then mixes with the flow path in the annulus. Predicting the correct quantity of purge flow necessary to prevent excessive ingestion of hot gases while, at the same time, minimizing the penalties in terms of engine efficiency and stage aerodynamics represents a great challenge for the designers and a crucial point for the design of reliable engines. Such estimate is governed by unsteady phenomena, and computational fluid dynamics (CFD) approaches are still expensive and time consuming, especially if 3D domains and unsteady conditions have to be simulated. Fundamental test cases, replicating actual engines geometries, are still a valid approach to calibrate correlations or simplified models such as the so-called orifice model. However, most of the experimental studies deal with test rigs at room temperature and do not take into account the effect of the density ratio (DR) between purge and main flows. To fill this gap, the present article reports the impact of the density ratio on the rim sealing effectiveness by performing a nonintrusive diagnostic based on the pressure-sensitive paint (PSP) technique on both the stator side and the rotor side. The analysis was performed on a cold rotating cavity rig, developed for the study of hot gas ingestion, where two different values of density ratios were tested by using N2 (DR = 1) and CO2 (DR = 1.52) as purge flow. The data extracted from the PSP seal effectiveness maps allowed to calibrate the orifice model for the stator side and to fit the coefficients of the buffer ratio model for the rotor surface at different flow conditions where the externally induced ingress is the dominant mechanism for gas ingestion. The results highlighted the impact of the DR on the seal effectiveness and on the low-order models considered for the data analysis. In the end, it is shown that the obtained results can be used to scale experimental data, generally collected at DR close to one, toward more representative engine values where the difference between the density of purge and main flows cannot be neglected.
{"title":"IMPACT OF THE PURGE FLOW DENSITY RATIO ON THE RIM SEALING EFFECTIVENESS IN HOT GAS INGESTION MEASUREMENTS","authors":"Lorenzo Orsini, Alessio Picchi, Bruno Facchini, Alessio Bonini, Luca Innocenti","doi":"10.1115/1.4063755","DOIUrl":"https://doi.org/10.1115/1.4063755","url":null,"abstract":"Abstract The rim seals of gas turbines are used to control the ingestion of hot mainstream gas into the wheel space between the rotor disk and the stationary casing. Sealing air, which is generally used to pressurize the cavity space, flows through the seal clearance and then mixes with the flow path in the annulus. Predicting the correct quantity of purge flow necessary to prevent excessive ingestion of hot gases while, at the same time, minimizing the penalties in terms of engine efficiency and stage aerodynamics represents a great challenge for the designers and a crucial point for the design of reliable engines. Such estimate is governed by unsteady phenomena, and computational fluid dynamics (CFD) approaches are still expensive and time consuming, especially if 3D domains and unsteady conditions have to be simulated. Fundamental test cases, replicating actual engines geometries, are still a valid approach to calibrate correlations or simplified models such as the so-called orifice model. However, most of the experimental studies deal with test rigs at room temperature and do not take into account the effect of the density ratio (DR) between purge and main flows. To fill this gap, the present article reports the impact of the density ratio on the rim sealing effectiveness by performing a nonintrusive diagnostic based on the pressure-sensitive paint (PSP) technique on both the stator side and the rotor side. The analysis was performed on a cold rotating cavity rig, developed for the study of hot gas ingestion, where two different values of density ratios were tested by using N2 (DR = 1) and CO2 (DR = 1.52) as purge flow. The data extracted from the PSP seal effectiveness maps allowed to calibrate the orifice model for the stator side and to fit the coefficients of the buffer ratio model for the rotor surface at different flow conditions where the externally induced ingress is the dominant mechanism for gas ingestion. The results highlighted the impact of the DR on the seal effectiveness and on the low-order models considered for the data analysis. In the end, it is shown that the obtained results can be used to scale experimental data, generally collected at DR close to one, toward more representative engine values where the difference between the density of purge and main flows cannot be neglected.","PeriodicalId":49966,"journal":{"name":"Journal of Turbomachinery-Transactions of the Asme","volume":"28 64","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135765043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Amit Kumar, Akshay Kumar, Hitesh Chhugani, Shubhali More, Pradeep A M
Abstract In order to maximize the pressure ratio and efficiency, compressor designers have tried several unconventional design approaches. Tandem blading is one such unconventional design that promises a higher-pressure ratio per stage through a higher diffusion factor. The boundary layer growth over the aft rotor is therefore effectively controlled with the help of this gap-nozzle flow. The flow complexity is likely to increase in the case of a tandem rotor due to the twin leakage vortices, twin wake regions, and their interaction with the hub and casing boundary layers. Modern compressor blades are often designed with three-dimensional blade techniques such as sweep, lean, dihedral, end bent, etc., to reduce the various losses and achieve optimum performance. However, to the best of the author's knowledge, the effect of 3D blade designs on the performance of tandem rotors has not been fully explored so far. A comprehensive numerical investigation is undertaken to understand the effect of 3D designs on the performance of tandem blades. Axial sweep and dihedral failed to improve the performance of the tandem rotor. Significant improvement in the stall margin is observed for the forward chordwise-swept and negative lean tandem rotors and is largely attributed to lower tip incidence. The performance penalty of the forward-swept and negatively leaned cases can be reduced by integrating compound or variable lean and sweep into the design.
{"title":"UNDERSTANDING THE EFFECT OF THREE-DIMENSIONAL DESIGN IN TANDEM BLADE","authors":"Amit Kumar, Akshay Kumar, Hitesh Chhugani, Shubhali More, Pradeep A M","doi":"10.1115/1.4063924","DOIUrl":"https://doi.org/10.1115/1.4063924","url":null,"abstract":"Abstract In order to maximize the pressure ratio and efficiency, compressor designers have tried several unconventional design approaches. Tandem blading is one such unconventional design that promises a higher-pressure ratio per stage through a higher diffusion factor. The boundary layer growth over the aft rotor is therefore effectively controlled with the help of this gap-nozzle flow. The flow complexity is likely to increase in the case of a tandem rotor due to the twin leakage vortices, twin wake regions, and their interaction with the hub and casing boundary layers. Modern compressor blades are often designed with three-dimensional blade techniques such as sweep, lean, dihedral, end bent, etc., to reduce the various losses and achieve optimum performance. However, to the best of the author's knowledge, the effect of 3D blade designs on the performance of tandem rotors has not been fully explored so far. A comprehensive numerical investigation is undertaken to understand the effect of 3D designs on the performance of tandem blades. Axial sweep and dihedral failed to improve the performance of the tandem rotor. Significant improvement in the stall margin is observed for the forward chordwise-swept and negative lean tandem rotors and is largely attributed to lower tip incidence. The performance penalty of the forward-swept and negatively leaned cases can be reduced by integrating compound or variable lean and sweep into the design.","PeriodicalId":49966,"journal":{"name":"Journal of Turbomachinery-Transactions of the Asme","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136263570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Acar Çelik, Abhijit Mitra, Tapish Agarwal, John Clark, Ian Jacobi, Beni Cukurel
Abstract In this study, acoustic actuation was applied experimentally to massively separated flows on simplified hump geometries which mimic the pressure distribution over high-work-and-lift low Reynolds airfoils. The acoustic excitation demonstrated significant control over flow separation, resulting in higher relative lift enhancement than standard, localized actuation techniques with similar momentum coefficients. Full field velocity measurements were used to examine the transient behavior of the actuated flow in order to explain the physical mechanism of separation control. The velocity measurements revealed the presence of a viscous wall-mode that organized the vorticity upstream of the separation point. A spatiotemporal correlation analysis found that the generation of these wall modes in the attached flow was the dominant cause of the subsequent reorganization of the separating shear layer and the change in separation dynamics. The importance of wall-modes to acoustic flow control mechanism has important implications for the design of new acoustic control strategies for high-speed turbomachinery. Along these lines, the ramifications of this phenomena are explored over geometries which are designed to approximate flow fields in highspeed turbomachinery. At the conducive Strouhal number, which scale linearly with the square root of Reynolds numbers, up to 22% lift enhancement is observed for excitation amplitudes in the range of ∼128dB, typical to the engine environment. Of many diverse flow-control techniques, acoustics can be effectively employed in low Reynolds turbine blades, which are prone to flow separation in the offdesign conditions with the ever-increasing demand for higher flow turning.
{"title":"EXPLORING PHYSICS OF ACOUSTIC FLOW CONTROL OVER AIRFOILS TOWARDS POTENTIAL APPLICATION TO HIGH WORK AND LIFT TURBINES","authors":"Acar Çelik, Abhijit Mitra, Tapish Agarwal, John Clark, Ian Jacobi, Beni Cukurel","doi":"10.1115/1.4063923","DOIUrl":"https://doi.org/10.1115/1.4063923","url":null,"abstract":"Abstract In this study, acoustic actuation was applied experimentally to massively separated flows on simplified hump geometries which mimic the pressure distribution over high-work-and-lift low Reynolds airfoils. The acoustic excitation demonstrated significant control over flow separation, resulting in higher relative lift enhancement than standard, localized actuation techniques with similar momentum coefficients. Full field velocity measurements were used to examine the transient behavior of the actuated flow in order to explain the physical mechanism of separation control. The velocity measurements revealed the presence of a viscous wall-mode that organized the vorticity upstream of the separation point. A spatiotemporal correlation analysis found that the generation of these wall modes in the attached flow was the dominant cause of the subsequent reorganization of the separating shear layer and the change in separation dynamics. The importance of wall-modes to acoustic flow control mechanism has important implications for the design of new acoustic control strategies for high-speed turbomachinery. Along these lines, the ramifications of this phenomena are explored over geometries which are designed to approximate flow fields in highspeed turbomachinery. At the conducive Strouhal number, which scale linearly with the square root of Reynolds numbers, up to 22% lift enhancement is observed for excitation amplitudes in the range of ∼128dB, typical to the engine environment. Of many diverse flow-control techniques, acoustics can be effectively employed in low Reynolds turbine blades, which are prone to flow separation in the offdesign conditions with the ever-increasing demand for higher flow turning.","PeriodicalId":49966,"journal":{"name":"Journal of Turbomachinery-Transactions of the Asme","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136264051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 coolant jet interaction has a great influence on the superposition prediction of multirow film cooling. Although there have been many efforts to reveal the mechanics of additive effect in multirow film cooling, the available knowledge about developing the superposition method is still limited. The present work examines the film cooling effectiveness in two rows of fan-shaped holes by pressure sensitive paint technique, at the blowing ratios of 0.5 to 2.0 and the density ratio of 1.0. It is found that the impact of upstream flow on the downstream cooling film is reflected in the variation of turbulence intensity. The enhanced turbulence intensity is detrimental to the downstream film cooling effectiveness especially at the far away region. The mixing of upstream flow and coolant ejection starts at the leading edge of the hole exit. Thus, the streamwise width of the hole exit should be taken into consideration for better predicting the film cooling effectiveness around the holes. The cause of additive effect is that the coolant ejection at the second row affects the local mainstream entrainment. Then, a new correction factor, which characterizes the influence of coolant ejection on the mainstream entrainment of the upper row, is proposed for improving the classical Sellers method. The final result shows a good agreement with experimental data.
{"title":"Study on Additive Effect of Film Cooling Effectiveness in Two Rows of Fan-Shaped Holes","authors":"Chen Li, Baitao An, Jianjun Liu","doi":"10.1115/1.4063922","DOIUrl":"https://doi.org/10.1115/1.4063922","url":null,"abstract":"Abstract The coolant jet interaction has a great influence on the superposition prediction of multirow film cooling. Although there have been many efforts to reveal the mechanics of additive effect in multirow film cooling, the available knowledge about developing the superposition method is still limited. The present work examines the film cooling effectiveness in two rows of fan-shaped holes by pressure sensitive paint technique, at the blowing ratios of 0.5 to 2.0 and the density ratio of 1.0. It is found that the impact of upstream flow on the downstream cooling film is reflected in the variation of turbulence intensity. The enhanced turbulence intensity is detrimental to the downstream film cooling effectiveness especially at the far away region. The mixing of upstream flow and coolant ejection starts at the leading edge of the hole exit. Thus, the streamwise width of the hole exit should be taken into consideration for better predicting the film cooling effectiveness around the holes. The cause of additive effect is that the coolant ejection at the second row affects the local mainstream entrainment. Then, a new correction factor, which characterizes the influence of coolant ejection on the mainstream entrainment of the upper row, is proposed for improving the classical Sellers method. The final result shows a good agreement with experimental data.","PeriodicalId":49966,"journal":{"name":"Journal of Turbomachinery-Transactions of the Asme","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136262014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Cooling components in the hot section of a gas turbine is essential to component durability. Common methods of cooling include rib turbulators in internal passages and film cooling on external surfaces. The holes that produce the film cooling are fed from the internal channels often containing ribs. Consequently, there is an interdependence of internal heat transfer and external film cooling. The purpose of this study was to obtain a better understanding of the interaction of ribs and film cooling. To quantify the cooling performance the surface temperatures were measured from which overall effectiveness was calculated. For the experiments, additively manufactured test coupons were made of Inconel 718 to match engine Biot numbers. These test coupons had internal feed channels with and without ribs and had both cylindrical holes and meter diffuser shaped holes with 15° lateral expansion angles and a 1° forward expansion angle. A single rectangular channel was one type of feed channel. The other type of feed channels was individual circular channels with each circular channel supplying an individual film-cooling hole. The experimental results showed that the circular individual channels have 80% higher baseline overall effectiveness than the single rectangular channel without any film cooling. Ribbed turbulators without film cooling also increased the overall effectiveness by 21% for single rectangular channel and by 29% for the circular individual channels compared to the respective non-ribbed channels. Overall, a less effective supply channel will have a greater benefit from film-cooling than a highly effective supply channel.
{"title":"THE EFFECTS OF CHANNEL SUPPLIES ON OVERALL FILM-COOLING EFFECTIVENESS","authors":"Emma Veley, Karen A. Thole, David G. Bogard","doi":"10.1115/1.4063927","DOIUrl":"https://doi.org/10.1115/1.4063927","url":null,"abstract":"Abstract Cooling components in the hot section of a gas turbine is essential to component durability. Common methods of cooling include rib turbulators in internal passages and film cooling on external surfaces. The holes that produce the film cooling are fed from the internal channels often containing ribs. Consequently, there is an interdependence of internal heat transfer and external film cooling. The purpose of this study was to obtain a better understanding of the interaction of ribs and film cooling. To quantify the cooling performance the surface temperatures were measured from which overall effectiveness was calculated. For the experiments, additively manufactured test coupons were made of Inconel 718 to match engine Biot numbers. These test coupons had internal feed channels with and without ribs and had both cylindrical holes and meter diffuser shaped holes with 15° lateral expansion angles and a 1° forward expansion angle. A single rectangular channel was one type of feed channel. The other type of feed channels was individual circular channels with each circular channel supplying an individual film-cooling hole. The experimental results showed that the circular individual channels have 80% higher baseline overall effectiveness than the single rectangular channel without any film cooling. Ribbed turbulators without film cooling also increased the overall effectiveness by 21% for single rectangular channel and by 29% for the circular individual channels compared to the respective non-ribbed channels. Overall, a less effective supply channel will have a greater benefit from film-cooling than a highly effective supply channel.","PeriodicalId":49966,"journal":{"name":"Journal of Turbomachinery-Transactions of the Asme","volume":"169 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136264064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Corner separation is an inherently unsteady flow feature in an axial compressor cascade, it significantly affects the aerodynamic performance of compressors. The flow field of a highly-loaded compressor cascade at the Mach number of 0.59 under the moderate separation condition is simulated based on delayed detached eddy simulation. Comparisons of averaged flow field and transient flow field show that the three-dimensional corner separation flow is highly unsteady and composed of fine-scale vortex structures. The classical recognition of corner separation structures is a consequence of time-averaging. To better understand the contribution of unsteady structures to the averaged flow structures, the evolutions of flow fields in time series and the power spectrums are analyzed. A dominant periodic flow fluctuation is caused by the development of separating vortices with a characteristic frequency around 3500Hz, or at a Strouhal number of 0.75. Further, energy scales and spatiotemporal features of these dominant unsteady behaviors are analyzed using proper orthogonal decomposition and dynamic mode decomposition methods. Results show that the low-frequency behaviors mainly caused by the passage vortex at lower-span regions govern large-scale changes of separation flow in size and intensity and act with a certain intermittency. The vortex developing mode around 3500Hz prevails at higher regions affected by the concentrated shedding vortex. As the separating vortices dissipate approaching the midspan, the effect of the vortex developing mode on axial velocity fluctuation is reduced, although it dominates the pressure fluctuation with good stability in the whole passage.
{"title":"Unsteady Flow Structure of Corner Separation in a Highly Loaded Compressor Cascade","authors":"Weibo Zhong, Yangwei Liu, Yumeng Tang","doi":"10.1115/1.4063926","DOIUrl":"https://doi.org/10.1115/1.4063926","url":null,"abstract":"Abstract Corner separation is an inherently unsteady flow feature in an axial compressor cascade, it significantly affects the aerodynamic performance of compressors. The flow field of a highly-loaded compressor cascade at the Mach number of 0.59 under the moderate separation condition is simulated based on delayed detached eddy simulation. Comparisons of averaged flow field and transient flow field show that the three-dimensional corner separation flow is highly unsteady and composed of fine-scale vortex structures. The classical recognition of corner separation structures is a consequence of time-averaging. To better understand the contribution of unsteady structures to the averaged flow structures, the evolutions of flow fields in time series and the power spectrums are analyzed. A dominant periodic flow fluctuation is caused by the development of separating vortices with a characteristic frequency around 3500Hz, or at a Strouhal number of 0.75. Further, energy scales and spatiotemporal features of these dominant unsteady behaviors are analyzed using proper orthogonal decomposition and dynamic mode decomposition methods. Results show that the low-frequency behaviors mainly caused by the passage vortex at lower-span regions govern large-scale changes of separation flow in size and intensity and act with a certain intermittency. The vortex developing mode around 3500Hz prevails at higher regions affected by the concentrated shedding vortex. As the separating vortices dissipate approaching the midspan, the effect of the vortex developing mode on axial velocity fluctuation is reduced, although it dominates the pressure fluctuation with good stability in the whole passage.","PeriodicalId":49966,"journal":{"name":"Journal of Turbomachinery-Transactions of the Asme","volume":"51 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136262019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Hard-to-abate industrial processes, such as petrochemicals, have long been considered technically challenging to decarbonize. In response to the urgent demand to eliminate industrial CO2 emissions, a new class of energy-imparting turbomachines has been developed. These devices aim to convert mechanical into internal energy instead of pressurizing the gas, which enables high-temperature gas heating for a variety of applications. This paper is organized into three parts. First, the paper demonstrates the capabilities of the novel, customizable, repeating-stage axial turbo-heater for a hydrocarbon cracking example application. The study presents the new design requirements and working principles of this energy-imparting concept. The radically different objectives compared to a compressor enable ultra-high loading stage designs by avoiding the stability and efficiency constraints imposed on compressors. Within this new design space, the turbo-heater can achieve a loading coefficient ψ ≥ 4.0. Second, detailed numerical simulations of a multistage turbo-reactor with various vaneless space lengths are conducted. This work conclusively demonstrates the robustness of the aerodynamic design to maintain nominal work-input conditions even for the most compact arrangements despite employing a uniform blade design. Finally, having confirmed that the aerothermal restrictions on the vaneless space length can be removed, the designer is free to tailor the design to optimize the chemical reaction by (1) tailoring the residence time distribution (2) homogenizing reaction progress by mixing-out concentration gradients and (3) adjusting the rotational speed to account for variations in the reaction dynamics for different feedstocks.
{"title":"A NOVEL AXIAL ENERGY-IMPARTING TURBOMACHINE FOR HIGH-ENTHALPY GAS HEATING: ROBUSTNESS OF THE AERODYNAMIC DESIGN","authors":"Nikolas Karefyllidis, Dylan Rubini, Budimir Rosic, Liping Xu, Veli-Matti Purola","doi":"10.1115/1.4063928","DOIUrl":"https://doi.org/10.1115/1.4063928","url":null,"abstract":"Abstract Hard-to-abate industrial processes, such as petrochemicals, have long been considered technically challenging to decarbonize. In response to the urgent demand to eliminate industrial CO2 emissions, a new class of energy-imparting turbomachines has been developed. These devices aim to convert mechanical into internal energy instead of pressurizing the gas, which enables high-temperature gas heating for a variety of applications. This paper is organized into three parts. First, the paper demonstrates the capabilities of the novel, customizable, repeating-stage axial turbo-heater for a hydrocarbon cracking example application. The study presents the new design requirements and working principles of this energy-imparting concept. The radically different objectives compared to a compressor enable ultra-high loading stage designs by avoiding the stability and efficiency constraints imposed on compressors. Within this new design space, the turbo-heater can achieve a loading coefficient ψ ≥ 4.0. Second, detailed numerical simulations of a multistage turbo-reactor with various vaneless space lengths are conducted. This work conclusively demonstrates the robustness of the aerodynamic design to maintain nominal work-input conditions even for the most compact arrangements despite employing a uniform blade design. Finally, having confirmed that the aerothermal restrictions on the vaneless space length can be removed, the designer is free to tailor the design to optimize the chemical reaction by (1) tailoring the residence time distribution (2) homogenizing reaction progress by mixing-out concentration gradients and (3) adjusting the rotational speed to account for variations in the reaction dynamics for different feedstocks.","PeriodicalId":49966,"journal":{"name":"Journal of Turbomachinery-Transactions of the Asme","volume":"8 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136264054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Christopher Fuhrer, Nikola Kovachev, Damian M. Vogt, Ganesh Mahalingam, Stuart Mann
Abstract The growing demand of high flexibility and wide operating ranges of radial turbines in turbocharger applications necessi- tates new methods in the turbomachinery design process. Of- ten, design criteria such as high performance at certain operat- ing conditions or low inertia contradict the requirement for high durability. This paper demonstrates a newly developed optimiza- tion approach for radial turbines that allows to optimize for sev- eral design objectives. The presented approach is based on a parametric model of the turbine wheel geometry. On the one hand, the model is designed to capture the most important geometry and design features, and on the other hand, it is flexible for use on various machines. A surrogate model-based genetic algorithm is used to optimize the geometries with respect to several objectives, including efficiency, durabil- ity (HCF), Low-Cycle Fatigue (LCF), inertia and mass. Certain operating points or criteria can be particularly emphasized and specified constraints throughout the process allow for customized optimization. The simulations underlying the optimization are state-of-the-art CFD and FE analyses, involving the respective components. The newly developed and fully automated approach includes tasks of different disciplines. In the end, a selection of several promising geometries is examined more intimately to finally find a most suitable geometry for the given application. For the cur- rent study, this geometry has been manufactured and tested on a hot-gas-test facility to successfully validate the design process.
{"title":"MULTI-OBJECTIVE NUMERICAL OPTIMIZATION OF RADIAL TURBINES","authors":"Christopher Fuhrer, Nikola Kovachev, Damian M. Vogt, Ganesh Mahalingam, Stuart Mann","doi":"10.1115/1.4063929","DOIUrl":"https://doi.org/10.1115/1.4063929","url":null,"abstract":"Abstract The growing demand of high flexibility and wide operating ranges of radial turbines in turbocharger applications necessi- tates new methods in the turbomachinery design process. Of- ten, design criteria such as high performance at certain operat- ing conditions or low inertia contradict the requirement for high durability. This paper demonstrates a newly developed optimiza- tion approach for radial turbines that allows to optimize for sev- eral design objectives. The presented approach is based on a parametric model of the turbine wheel geometry. On the one hand, the model is designed to capture the most important geometry and design features, and on the other hand, it is flexible for use on various machines. A surrogate model-based genetic algorithm is used to optimize the geometries with respect to several objectives, including efficiency, durabil- ity (HCF), Low-Cycle Fatigue (LCF), inertia and mass. Certain operating points or criteria can be particularly emphasized and specified constraints throughout the process allow for customized optimization. The simulations underlying the optimization are state-of-the-art CFD and FE analyses, involving the respective components. The newly developed and fully automated approach includes tasks of different disciplines. In the end, a selection of several promising geometries is examined more intimately to finally find a most suitable geometry for the given application. For the cur- rent study, this geometry has been manufactured and tested on a hot-gas-test facility to successfully validate the design process.","PeriodicalId":49966,"journal":{"name":"Journal of Turbomachinery-Transactions of the Asme","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136263567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Richard Jackson, Zhihui Li, Loizos Christodoulou, Stephen Ambrose, Carl Sangan, Richard J Jefferson-Loveday, Gary D Lock, James Scobie
Abstract Minimizing the losses within a low-pressure turbine (LPT) system is critical for the design of next-generation ultra-high bypass ratio aero-engines. The stator-well cavity windage torque can be a significant source of loss within the system, influenced by the ingestion of mainstream annulus air with a tangential velocity opposite to that of the rotor. This paper presents experimental and numerical results of three carefully designed Flow Control Concepts (FCCs) – additional geometric features on the stator surfaces, which were optimized to minimize the windage torque within a scaled, engine-representative stator-well cavity. FCC1 and FCC2 featured rows of guide vanes at the inlet to the downstream and upstream wheel-spaces, respectively. FCC3 combined FCC1 and FCC2. Superposed flows were introduced to the upstream section of the cavity, which modelled the low radius coolant and higher radius leakage between the rotor blades. In addition to torque measurements, total and static pressures were collected, from which the cavity swirl ratio was derived. Additional swirl measurements were collected using a five-hole aerodynamic probe, which traversed radially at the entrance and exit of the cavity. A cavity windage torque reduction of 55% on the baseline (which has no flow control) was measured for FCC3, at the design condition with superposed flow. For this concept, an increase in the cavity swirl in both the upstream and downstream wheel-spaces was demonstrated experimentally and numerically. With increasing superposed flow, the contribution of FCC1 surpassed FCC2, due to more mass flow entering
{"title":"Windage Torque Reduction in Low-Pressure Turbine Cavities Part 2: Experimental and Numerical Results","authors":"Richard Jackson, Zhihui Li, Loizos Christodoulou, Stephen Ambrose, Carl Sangan, Richard J Jefferson-Loveday, Gary D Lock, James Scobie","doi":"10.1115/1.4063876","DOIUrl":"https://doi.org/10.1115/1.4063876","url":null,"abstract":"Abstract Minimizing the losses within a low-pressure turbine (LPT) system is critical for the design of next-generation ultra-high bypass ratio aero-engines. The stator-well cavity windage torque can be a significant source of loss within the system, influenced by the ingestion of mainstream annulus air with a tangential velocity opposite to that of the rotor. This paper presents experimental and numerical results of three carefully designed Flow Control Concepts (FCCs) – additional geometric features on the stator surfaces, which were optimized to minimize the windage torque within a scaled, engine-representative stator-well cavity. FCC1 and FCC2 featured rows of guide vanes at the inlet to the downstream and upstream wheel-spaces, respectively. FCC3 combined FCC1 and FCC2. Superposed flows were introduced to the upstream section of the cavity, which modelled the low radius coolant and higher radius leakage between the rotor blades. In addition to torque measurements, total and static pressures were collected, from which the cavity swirl ratio was derived. Additional swirl measurements were collected using a five-hole aerodynamic probe, which traversed radially at the entrance and exit of the cavity. A cavity windage torque reduction of 55% on the baseline (which has no flow control) was measured for FCC3, at the design condition with superposed flow. For this concept, an increase in the cavity swirl in both the upstream and downstream wheel-spaces was demonstrated experimentally and numerically. With increasing superposed flow, the contribution of FCC1 surpassed FCC2, due to more mass flow entering","PeriodicalId":49966,"journal":{"name":"Journal of Turbomachinery-Transactions of the Asme","volume":"39 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135273954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 paper describes a simple and efficient physics-based method for designing optimal transonic multistage compressor rotors. The key to this novel method is that the spanwise variation of the parameter which controls the three-dimensional shock structure, the area ratio between the throat and the inlet, ‘Athroat /Ainlet’, is extracted directly from the 3D CFD. The spanwise distribution of the area ratio is then adjusted iteratively to balance the shock structure across the blade span. Because of this, the blade design will be called ‘aerodynamically balanced’. The new design method converges in a few iterations and is physically intuitive because it accounts for the real changes in the 3D area ratio that directly controls the shock structure. Specifically, changes in both the spanwise 3D flow and in the rotor's operating condition; thus aiding designer understanding. To demonstrate this, two example design cases are shown in the paper. A transonic rotor within a multistage civil compressor with variable upstream stator vanes, and an embedded rotor within a multistage military fan. The method is shown to: (1) improve both the operating range and the design efficiency while retaining the compressor's overall matching, and (2) allow a balanced design to be simultaneously achieved at multiple shaft speeds. The result is a method which simplifies the multistage transonic compressor rotor design process and therefore has great practical utility.
{"title":"DESIGN OF AERODYNAMICALLY BALANCED TRANSONIC COMPRESSOR ROTORS","authors":"Demetrios Lefas, Robert Miller","doi":"10.1115/1.4063881","DOIUrl":"https://doi.org/10.1115/1.4063881","url":null,"abstract":"Abstract This paper describes a simple and efficient physics-based method for designing optimal transonic multistage compressor rotors. The key to this novel method is that the spanwise variation of the parameter which controls the three-dimensional shock structure, the area ratio between the throat and the inlet, ‘Athroat /Ainlet’, is extracted directly from the 3D CFD. The spanwise distribution of the area ratio is then adjusted iteratively to balance the shock structure across the blade span. Because of this, the blade design will be called ‘aerodynamically balanced’. The new design method converges in a few iterations and is physically intuitive because it accounts for the real changes in the 3D area ratio that directly controls the shock structure. Specifically, changes in both the spanwise 3D flow and in the rotor's operating condition; thus aiding designer understanding. To demonstrate this, two example design cases are shown in the paper. A transonic rotor within a multistage civil compressor with variable upstream stator vanes, and an embedded rotor within a multistage military fan. The method is shown to: (1) improve both the operating range and the design efficiency while retaining the compressor's overall matching, and (2) allow a balanced design to be simultaneously achieved at multiple shaft speeds. The result is a method which simplifies the multistage transonic compressor rotor design process and therefore has great practical utility.","PeriodicalId":49966,"journal":{"name":"Journal of Turbomachinery-Transactions of the Asme","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135267878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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