Bertolotti Luc, Richard Jefferson-Loveday, Stephen Ambrose, Evgenia Korsukova
In aero-engine bearing chambers, two-phase shearing flows are difficult to predict as Computational Fluid Dynamics (CFD) RANS models tend to overestimate interfacial turbulence levels, leading to inaccuracies in the modelling of the flow. Turbulence damping methods have been developed to address this problem, such as Egorov’s correction, however, this method is mesh dependent and results differ considerably according to the choice of turbulence damping coefficient. In addition, this approach assumes a smooth interface between the air and oil phases when in reality they are wavy. In this paper, a Machine Learning method is used to inform an unsteady RANS turbulence modelling. It is trained using high fidelity quasi-DNS simulation data and used to provide an appropriate correction to the popular Wilcox’s standard RANS k−ω turbulence model. The correction consists of a machine learning-predicted source term which is used to adjust the energy budget in the RANS transport equations. Demonstration of the approach is presented for a range of interfacial flow regimes.
{"title":"High-fidelity CFD-trained machine learning to inform RANS-modelled interfacial turbulence","authors":"Bertolotti Luc, Richard Jefferson-Loveday, Stephen Ambrose, Evgenia Korsukova","doi":"10.33737/jgpps/166558","DOIUrl":"https://doi.org/10.33737/jgpps/166558","url":null,"abstract":"In aero-engine bearing chambers, two-phase shearing flows are difficult to predict as Computational Fluid Dynamics (CFD) RANS models tend to overestimate interfacial turbulence levels, leading to inaccuracies in the modelling of the flow. Turbulence damping methods have been developed to address this problem, such as Egorov’s correction, however, this method is mesh dependent and results differ considerably according to the choice of turbulence damping coefficient. In addition, this approach assumes a smooth interface between the air and oil phases when in reality they are wavy. In this paper, a Machine Learning method is used to inform an unsteady RANS turbulence modelling. It is trained using high fidelity quasi-DNS simulation data and used to provide an appropriate correction to the popular Wilcox’s standard RANS <inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\" overflow=\"scroll\"><mml:mi>k</mml:mi><mml:mo>−</mml:mo><mml:mi>ω</mml:mi></mml:math></inline-formula> turbulence model. The correction consists of a machine learning-predicted source term which is used to adjust the energy budget in the RANS transport equations. Demonstration of the approach is presented for a range of interfacial flow regimes.","PeriodicalId":53002,"journal":{"name":"Journal of the Global Power and Propulsion Society","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135265489","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}
In gas turbines and jet engines, stagger angle and tip gap variations between adjacent blades lead to the deterioration of performance. To evaluate the effect of manufacturing tolerance on performance, a CFD-based uncertainty quantification analysis is performed in this work. However, evaluating dozens of thousands of rotor assembly through CFD simulations would be computationally prohibitive. A surrogate model is thus developed to predict compressor performance given an ordered set of manufactured blades. The model is used to predict the influence of tip gap and stagger angle variations on maximum isentropic efficiency. The results confirm that the best arrangement is obtained by minimizing the stagger angle variation between adjacent blades, and by maximizing the tip gap variation. Another finding is that the best arrangement yields the lowest variability, the range of maximum efficiency being 4 times sharper (resp. 2 times) than worst arrangement for stagger angle variations (resp. tip gap variations). Not measuring manufacturing tolerance, or not specifying any strategy for the blade arrangement, lead to variability as large as the worst arrangement.
{"title":"Development of a surrogate model for uncertainty quantification of compressor performance due to manufacturing tolerance","authors":"Quentin Rendu, Loic Salles","doi":"10.33737/jgpps/168293","DOIUrl":"https://doi.org/10.33737/jgpps/168293","url":null,"abstract":"In gas turbines and jet engines, stagger angle and tip gap variations between adjacent blades lead to the deterioration of performance. To evaluate the effect of manufacturing tolerance on performance, a CFD-based uncertainty quantification analysis is performed in this work. However, evaluating dozens of thousands of rotor assembly through CFD simulations would be computationally prohibitive. A surrogate model is thus developed to predict compressor performance given an ordered set of manufactured blades. The model is used to predict the influence of tip gap and stagger angle variations on maximum isentropic efficiency. The results confirm that the best arrangement is obtained by minimizing the stagger angle variation between adjacent blades, and by maximizing the tip gap variation. Another finding is that the best arrangement yields the lowest variability, the range of maximum efficiency being 4 times sharper (resp. 2 times) than worst arrangement for stagger angle variations (resp. tip gap variations). Not measuring manufacturing tolerance, or not specifying any strategy for the blade arrangement, lead to variability as large as the worst arrangement.","PeriodicalId":53002,"journal":{"name":"Journal of the Global Power and Propulsion Society","volume":"259 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136119829","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}
Over the last several decades, turbine efficiency has improved significantly, resulting in higher turbine operating temperatures that negatively affect the lubricating oil circulating through the system. Exposure to high temperatures results in oil degradation and the eventual formation of solid deposits in the oil which greatly limit the oil’s ability to reduce wear and cool the turbine components. An experimental apparatus was designed and built to allow for the studying and better understanding of this phenomenon. The apparatus consists of a flow loop with a heated test section through which the oil is pumped. The oil that comes into contact with the hot surfaces degrades and forms solid deposits. As time passes, the deposit buildup decreases the heat transfer that occurs at the test section. The bulk oil temperatures into and out of the test section are used as indicators of the deposit induction time and buildup rate, and the deposits may be analyzed at the end of the experiment. Air or an inert gas may be used to pressurize the system up to 69 bar, while test section surface temperatures may be as high as 650°C. Data from one of the initial tests performed with the apparatus using a gas turbine lube oil are included in this paper. The test resulted in the clear formation of solid deposits on the heated surfaces and in the data that show the decrease in the bulk oil temperature over time due to their formation. Assembly and testing of the apparatus have been completed, and it is now fully operational and ready for future studies on lubricating oil thermal degradation and oxidation.
{"title":"Coking of gas turbine lubrication oils at elevated temperatures","authors":"Raquel Juárez, E. Petersen","doi":"10.33737/jgpps/168292","DOIUrl":"https://doi.org/10.33737/jgpps/168292","url":null,"abstract":"Over the last several decades, turbine efficiency has improved significantly, resulting in higher turbine operating temperatures that negatively affect the lubricating oil circulating through the system. Exposure to high temperatures results in oil degradation and the eventual formation of solid deposits in the oil which greatly limit the oil’s ability to reduce wear and cool the turbine components. An experimental apparatus was designed and built to allow for the studying and better understanding of this phenomenon. The apparatus consists of a flow loop with a heated test section through which the oil is pumped. The oil that comes into contact with the hot surfaces degrades and forms solid deposits. As time passes, the deposit buildup decreases the heat transfer that occurs at the test section. The bulk oil temperatures into and out of the test section are used as indicators of the deposit induction time and buildup rate, and the deposits may be analyzed at the end of the experiment. Air or an inert gas may be used to pressurize the system up to 69 bar, while test section surface temperatures may be as high as 650°C. Data from one of the initial tests performed with the apparatus using a gas turbine lube oil are included in this paper. The test resulted in the clear formation of solid deposits on the heated surfaces and in the data that show the decrease in the bulk oil temperature over time due to their formation. Assembly and testing of the apparatus have been completed, and it is now fully operational and ready for future studies on lubricating oil thermal degradation and oxidation.","PeriodicalId":53002,"journal":{"name":"Journal of the Global Power and Propulsion Society","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47045325","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}
Mitsubishi Heavy Industries, Ltd. (MHI) Group has been developing additive manufacturing (AM) as a method that can manufacture parts with complex shapes and considering its application to manufacturing processes. In combustor components, application of AM process to rapid prototyping and multi-cluster nozzles for hydrogen or ammonia gas fuel is being considered. In turbine parts, with the aim of improving performance by reducing the amount of cooling air, the adoption of a complex internal cooling structure, which cannot be made with conventional manufacturing methods but can only be made by AM, is being considered. This paper describes design for AM technology for gas turbine components and metal AM process technology such as building simulation based high stiffness support design and pre-set distortion, microstructure control by laser scanning conditions, quality control through in-process monitoring tools and application of AM technology to gas Turbine Components.
{"title":"Development of metal AM technology for gas turbine components","authors":"Shuji Tanigawa, Masahito Kataoka, M. Taneike, Ryuta Ito, Takanao Komaki, Norihiko Motoyama","doi":"10.33737/jgpps/163429","DOIUrl":"https://doi.org/10.33737/jgpps/163429","url":null,"abstract":"Mitsubishi Heavy Industries, Ltd. (MHI) Group has been developing additive manufacturing (AM) as a method that can manufacture parts with complex shapes and considering its application to manufacturing processes. In combustor components, application of AM process to rapid prototyping and multi-cluster nozzles for hydrogen or ammonia gas fuel is being considered. In turbine parts, with the aim of improving performance by reducing the amount of cooling air, the adoption of a complex internal cooling structure, which cannot be made with conventional manufacturing methods but can only be made by AM, is being considered. This paper describes design for AM technology for gas turbine components and metal AM process technology such as building simulation based high stiffness support design and pre-set distortion, microstructure control by laser scanning conditions, quality control through in-process monitoring tools and application of AM technology to gas Turbine Components.","PeriodicalId":53002,"journal":{"name":"Journal of the Global Power and Propulsion Society","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42416931","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}
Additive manufacturing (AM) allows for the rapid fabrication of complex components relative to conventional fabrication methods aiding in the development and testing of advanced turbine cooling methods. The repeatability of printed geometric features in the same part is required to maintain part quality, flow, and heat transfer. It is widely understood as to the impact that the additional roughness of AM provides with regards to part quality, but part variability also leads to differences in performance either locally in considering a single airfoil or globally when considering an entire stage. Previous studies have shown the importance of certain process parameters, build directions, and feature sizes on the part quality when printing a part using AM. As processes have continued to evolve, other artifacts of AM have arisen such as the location on the build plate. This article highlights the progress that has been made on printing commonly used cooling features by either considering simple straight coupons or a curved vane leading edge. Also discussed is the variability that exists and the resulting convective heat transfer and pressure losses. Results indicate that the variation of roughness between components and the part-to-part variations increased the further the component was from the laser source on the build plate. Similarly, the variation and levels in the pressure loss and heat transfer of the cooling channels also increased when samples were placed further from the laser source on the build plate.
{"title":"Variability in additively manufactured turbine cooling features","authors":"Alexander Wildgoose, K. Thole","doi":"10.33737/jgpps/162654","DOIUrl":"https://doi.org/10.33737/jgpps/162654","url":null,"abstract":"Additive manufacturing (AM) allows for the rapid fabrication of complex components relative to conventional fabrication methods aiding in the development and testing of advanced turbine cooling methods. The repeatability of printed geometric features in the same part is required to maintain part quality, flow, and heat transfer. It is widely understood as to the impact that the additional roughness of AM provides with regards to part quality, but part variability also leads to differences in performance either locally in considering a single airfoil or globally when considering an entire stage. Previous studies have shown the importance of certain process parameters, build directions, and feature sizes on the part quality when printing a part using AM. As processes have continued to evolve, other artifacts of AM have arisen such as the location on the build plate. This article highlights the progress that has been made on printing commonly used cooling features by either considering simple straight coupons or a curved vane leading edge. Also discussed is the variability that exists and the resulting convective heat transfer and pressure losses. Results indicate that the variation of roughness between components and the part-to-part variations increased the further the component was from the laser source on the build plate. Similarly, the variation and levels in the pressure loss and heat transfer of the cooling channels also increased when samples were placed further from the laser source on the build plate.","PeriodicalId":53002,"journal":{"name":"Journal of the Global Power and Propulsion Society","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46295538","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}
{"title":"Editorial: Some Advances in Additive Manufacturing for Aerothermal Technologies","authors":"Li He","doi":"10.33737/jgpps/168474","DOIUrl":"https://doi.org/10.33737/jgpps/168474","url":null,"abstract":"","PeriodicalId":53002,"journal":{"name":"Journal of the Global Power and Propulsion Society","volume":"1 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41491243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The requirements for new generation vehicles in terms of the flight speed, thrust–weight ratio, and maneuverability necessitate the development of high performance and reliable propulsion systems where active thermal protection technology plays a crucial role. Transpiration cooling based on a microporous structure is considered as one of the most promising techniques for protecting the high heat flux walls from ablation in aerospace applications. Unlike conventional fabrication methods, additive manufacturing (AM) has been applied to fabricate three-dimensional (3D) porous structures with customized geometries that are specific to applications, i.e., in terms of the design of features such as the pore diameter, pore density, porosity, and pore morphology. Three major AM technologies (selective laser melting, inkjet, and stereolithography) followed by a post-printing process have been proposed for the additive manufacture of porous structures. In particular, 3D-printed porous structures have great promise for transpiration cooling applications. In this review, we discuss the detailed steps of porous structure topology design and a general framework is presented for AM. The heat transfer and strength performance are also provided for porous parts fabricated by AM. Furthermore, the applications of 3D-printed porous media in transpiration cooling with different regimes are described. This review concludes by explaining the current challenges and prospects for the next generation of 3D-printed porous structures in transpiration cooling systems.
{"title":"Fundamentals and recent progress of additive manufacturing-assisted porous materials on transpiration cooling","authors":"R. Xu, Zhilong Cheng, Peixue Jiang","doi":"10.33737/jgpps/166418","DOIUrl":"https://doi.org/10.33737/jgpps/166418","url":null,"abstract":"The requirements for new generation vehicles in terms of the flight speed, thrust–weight ratio, and maneuverability necessitate the development of high performance and reliable propulsion systems where active thermal protection technology plays a crucial role. Transpiration cooling based on a microporous structure is considered as one of the most promising techniques for protecting the high heat flux walls from ablation in aerospace applications. Unlike conventional fabrication methods, additive manufacturing (AM) has been applied to fabricate three-dimensional (3D) porous structures with customized geometries that are specific to applications, i.e., in terms of the design of features such as the pore diameter, pore density, porosity, and pore morphology. Three major AM technologies (selective laser melting, inkjet, and stereolithography) followed by a post-printing process have been proposed for the additive manufacture of porous structures. In particular, 3D-printed porous structures have great promise for transpiration cooling applications. In this review, we discuss the detailed steps of porous structure topology design and a general framework is presented for AM. The heat transfer and strength performance are also provided for porous parts fabricated by AM. Furthermore, the applications of 3D-printed porous media in transpiration cooling with different regimes are described. This review concludes by explaining the current challenges and prospects for the next generation of 3D-printed porous structures in transpiration cooling systems.","PeriodicalId":53002,"journal":{"name":"Journal of the Global Power and Propulsion Society","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47920196","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}
Mesh adaptation of unstructured meshes for aerodynamic simulations, that typically resolve the Reynolds Averaged Navier-Stokes (RANS) equations, is a promising approach to enable high numerical precision on complex geometries. Its objective is to minimize the discretization error without using empirical meshing guidelines. The most common approach of mesh adaptation is the “feature-based” isotropic mesh adaptation: from an initial flow prediction on an isotropic unstructured mesh, a local error estimator is computed using a flow variable. It is then used to adapt the mesh using isotropic tetrahedra. Additional near-wall resolution can be achieved by extruding prism layers from the walls. A more efficient approach is to use anisotropic mesh adaptation purely with tetrahedra that are stretched to follow the flow's preferential directions. In this work, we demonstrate the abilities of feature-based isotropic and anisotropic mesh adaptation on a complex flow phenomenon of importance for jet engines: flow separation in a nacelle under crosswind conditions. Two different solvers, adapted for either isotropic or anisotropic meshes, are employed. Results are compared with standard unstructured simulations with user-imposed mesh refinements and highlight the ability of mesh adaptation to automatically capture all the relevant flow phenomena without any user input and at reduced mesh size.
{"title":"Isotropic and anisotropic mesh adaptation for RANS simulations of a nacelle under crosswind conditions","authors":"Billon Laure, Papadogiannis Dimitrios, Alauzet Frédéric","doi":"10.33737/jgpps/162640","DOIUrl":"https://doi.org/10.33737/jgpps/162640","url":null,"abstract":"Mesh adaptation of unstructured meshes for aerodynamic simulations, that typically resolve the Reynolds Averaged Navier-Stokes (RANS) equations, is a promising approach to enable high numerical precision on complex geometries. Its objective is to minimize the discretization error without using empirical meshing guidelines. The most common approach of mesh adaptation is the “feature-based” isotropic mesh adaptation: from an initial flow prediction on an isotropic unstructured mesh, a local error estimator is computed using a flow variable. It is then used to adapt the mesh using isotropic tetrahedra. Additional near-wall resolution can be achieved by extruding prism layers from the walls. A more efficient approach is to use anisotropic mesh adaptation purely with tetrahedra that are stretched to follow the flow's preferential directions. In this work, we demonstrate the abilities of feature-based isotropic and anisotropic mesh adaptation on a complex flow phenomenon of importance for jet engines: flow separation in a nacelle under crosswind conditions. Two different solvers, adapted for either isotropic or anisotropic meshes, are employed. Results are compared with standard unstructured simulations with user-imposed mesh refinements and highlight the ability of mesh adaptation to automatically capture all the relevant flow phenomena without any user input and at reduced mesh size.","PeriodicalId":53002,"journal":{"name":"Journal of the Global Power and Propulsion Society","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48263387","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}
Dogan Bicat, Katharina Stichling, Maximilian Elfner, Hans-Jörg Bauer, Knut Lehmann
Cyclone cooling is a promising method for a more effective internal cooling of turbine rotor blades with simplified internal channels including a swirling flow to enhance internal heat transfer. Previous studies have led to the conclusion that improving the cooling performance requires an adapted film cooling design, tailored to the cyclone cooling application. In this paper, a turbine rotor blade with realistic, complex features including the cyclone cooling design is investigated experimentally using infrared thermography to capture surface temperature. The objective is to analyze the influence of increased film cooling hole diameter on a cyclone-cooled blade’s surface temperature. For this purpose, the diameter of the holes at the blade’s leading edge, which are fed by the cyclone channel, is increased. The tests are performed for different coolant mass flow rates and swirl numbers. Additionally, CFD simulations are performed to analyze the aerodynamics of the cooling air. The test results show that the surface temperature at the leading edge can be decreased by increasing the diameter of the film cooling holes, however, adversely affecting the remaining blade surface. This can be explained by a redistribution of the supplied coolant. The increase of cooling effectiveness at the leading edge is at the highest when a low swirl is generated.
{"title":"Experimental investigation of the influence of film cooling hole diameter on the total cooling effectiveness for cyclone-cooled turbine blades","authors":"Dogan Bicat, Katharina Stichling, Maximilian Elfner, Hans-Jörg Bauer, Knut Lehmann","doi":"10.33737/jgpps/165825","DOIUrl":"https://doi.org/10.33737/jgpps/165825","url":null,"abstract":"Cyclone cooling is a promising method for a more effective internal cooling of turbine rotor blades with simplified internal channels including a swirling flow to enhance internal heat transfer. Previous studies have led to the conclusion that improving the cooling performance requires an adapted film cooling design, tailored to the cyclone cooling application. In this paper, a turbine rotor blade with realistic, complex features including the cyclone cooling design is investigated experimentally using infrared thermography to capture surface temperature. The objective is to analyze the influence of increased film cooling hole diameter on a cyclone-cooled blade’s surface temperature. For this purpose, the diameter of the holes at the blade’s leading edge, which are fed by the cyclone channel, is increased. The tests are performed for different coolant mass flow rates and swirl numbers. Additionally, CFD simulations are performed to analyze the aerodynamics of the cooling air. The test results show that the surface temperature at the leading edge can be decreased by increasing the diameter of the film cooling holes, however, adversely affecting the remaining blade surface. This can be explained by a redistribution of the supplied coolant. The increase of cooling effectiveness at the leading edge is at the highest when a low swirl is generated.","PeriodicalId":53002,"journal":{"name":"Journal of the Global Power and Propulsion Society","volume":"182 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136016017","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}
Sebastian Kurth, Cengiz Kenan, Moeller Daniel, Wein Lars, J. Seume
In recent years, the research on roughness has focused on various roughness features, rather than the roughness height only, in order to improve the understanding of roughness effects on wall bounded flows. A special focus is placed on the skewness of the roughness height profile. The skewness measures whether the height profile is dominated by negative or positive roughness elements. Surfaces with both features can be found on worn blades: On the leading edge, roughness is caused by the impact of particles resulting in a negative skewness. Rough surfaces around the trailing edge, however, develop due to depositions leading to a positive skewness. In this paper, rough surfaces taken from a compressor blade of an aero engine are systematically varied to investigate the isolated effect of skewness on aerodynamic losses. By direct numerical simulations of a periodic flow channel. The results show that the skewness has a major influence on loss generation. Based on these results, an existing model which essentially uses the shape-and-density parameter, is extended by a skewness factor. The modified correlation predicts the influence of the rough surfaces investigated well.
{"title":"Systematic roughness variation to model the influence of skewness on wall bounded flows","authors":"Sebastian Kurth, Cengiz Kenan, Moeller Daniel, Wein Lars, J. Seume","doi":"10.33737/jgpps/163089","DOIUrl":"https://doi.org/10.33737/jgpps/163089","url":null,"abstract":"In recent years, the research on roughness has focused on various roughness features, rather than the roughness height only, in order to improve the understanding of roughness effects on wall bounded flows. A special focus is placed on the skewness of the roughness height profile. The skewness measures whether the height profile is dominated by negative or positive roughness elements. Surfaces with both features can be found on worn blades: On the leading edge, roughness is caused by the impact of particles resulting in a negative skewness. Rough surfaces around the trailing edge, however, develop due to depositions leading to a positive skewness.\u0000\u0000In this paper, rough surfaces taken from a compressor blade of an aero engine are systematically varied to investigate the isolated effect of skewness on aerodynamic losses. By direct numerical simulations of a periodic flow channel. The results show that the skewness has a major influence on loss generation. Based on these results, an existing model which essentially uses the shape-and-density parameter, is extended by a skewness factor. The modified correlation predicts the influence of the rough surfaces investigated well.","PeriodicalId":53002,"journal":{"name":"Journal of the Global Power and Propulsion Society","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2023-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48242461","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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