The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform
David G. Bogard - One of the best experts on this subject based on the ideXlab platform.
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Realistic Trench Film Cooling With a Thermal Barrier Coating and Deposition
Journal of Turbomachinery, 2014Co-Authors: David A. Kistenmacher, F. Todd Davidson, David G. BogardAbstract:Thermal barrier coatings (TBC’s) see extensive use in high temperature gas turbines. However, little work has been done to experimentally characterize the combination of TBC and film cooling. The purpose of this study is to investigate the cooling performance of a Thermally conducting turbine vane with a realistic film cooling trench geometry embedded in TBC. Additionally, the effect of contaminant deposition on the realistic trench was studied. The trench is termed realistic because it takes into account probable manufacturing limitations. The vane model and TBC used for this study were designed to match the Thermal behavior of an actual gas turbine vane with TBC by properly scaling their convective heat transfer coefficients, Thermal conductivities, and characteristic length scales. This study built upon previously published results with various film cooling geometries consisting of round holes, craters, an ideal trench, and a novel trench. The previous study showed that large changes in blowing ratio resulted in negligible effects on cooling performance. Changes to film cooling geometry also resulted in minor effects on cooling performance. This study found that the realistic trench and an idealized trench perform similarly. However, the width of the realistic trench left the vane wall more exposed to mainstream temperatures, especially at lower film coolant flow rates. This study also found that the trench designs helped to mitigate deposition formation better than round holes; however, the realistic trench was more prone to deposition within the trench. The overall cooling effectiveness was similar for both trench designs and relatively unchanged from the pre-deposition performance while the overall cooling effectiveness for round holes increased due to the Additional Thermal Insulation offered by the unmitigated deposition.Copyright © 2013 by ASME
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A Study of Deposition on a Turbine Vane With a Thermal Barrier Coating and Various Film Cooling Geometries
Journal of Turbomachinery, 2013Co-Authors: F. Todd Davidson, David A. Kistenmacher, David G. BogardAbstract:Recent interest has been shown in using synthetic gaseous (syngas) fuels to power gas turbine engines. An important issue concerning these fuels is the potential for increased contaminant deposition that can inhibit cooling designs and expedite the material degradation of vital turbine components. The purpose of this study was to provide a detailed understanding of how contaminants deposit on the surface of a turbine vane with a Thermal barrier coating (TBC). The vane model used in this study was designed to match the Thermal behavior of real engine components by properly scaling the convective heat transfer coefficients as well as the Thermal conductivity of the vane wall. Four different film cooling configurations were studied: round holes, craters, a trench, and a modified trench. The contaminants used in this study were small particles of paraffin wax that were sprayed into the mainstream flow of the wind tunnel. The wax particles modeled both the molten nature of contaminants in an engine as well as the particle trajectory by properly matching the expected range of Stokes number. This study found that the presence of film cooling significantly increased the accumulation of deposits. It was also found that the deposition behavior was strongly affected by the film cooling configuration that was used on the pressure side of the vane. The craters and trench performed the best in mitigating the accumulation of deposits immediately downstream of the film cooling configuration. In general, the presence of deposits reduced the film cooling performance on the surface of the TBC. However, the Additional Thermal Insulation provided by the deposits improved the cooling performance at the interface of the TBC and vane wall.
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Realistic Trench Film Cooling With a Thermal Barrier Coating and Deposition
Volume 3B: Heat Transfer, 2013Co-Authors: David A. Kistenmacher, F. Todd Davidson, David G. BogardAbstract:Thermal barrier coatings (TBC’s) see extensive use in high temperature gas turbines. However, little work has been done to experimentally characterize the combination of TBC and film cooling. The purpose of this study is to investigate the cooling performance of a Thermally conducting turbine vane with a realistic film cooling trench geometry embedded in TBC. Additionally, the effect of contaminant deposition on the realistic trench was studied. The trench is termed realistic because it takes into account probable manufacturing limitations. The vane model and TBC used for this study were designed to match the Thermal behavior of an actual gas turbine vane with TBC by properly scaling their convective heat transfer coefficients, Thermal conductivities, and characteristic length scales. This study built upon previously published results with various film cooling geometries consisting of round holes, craters, an ideal trench, and a novel trench. The previous study showed that large changes in blowing ratio resulted in negligible effects on cooling performance. Changes to film cooling geometry also resulted in minor effects on cooling performance. This study found that the realistic trench and an idealized trench perform similarly. However, the width of the realistic trench left the vane wall more exposed to mainstream temperatures, especially at lower film coolant flow rates. This study also found that the trench designs helped to mitigate deposition formation better than round holes; however, the realistic trench was more prone to deposition within the trench. The overall cooling effectiveness was similar for both trench designs and relatively unchanged from the pre-deposition performance while the overall cooling effectiveness for round holes increased due to the Additional Thermal Insulation offered by the unmitigated deposition.
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A Study of Deposition on a Turbine Vane With a Thermal Barrier Coating and Various Film Cooling Geometries
Volume 4: Heat Transfer Parts A and B, 2012Co-Authors: F. Todd Davidson, David A. Kistenmacher, David G. BogardAbstract:Recent interest has been shown in using synthetic gaseous (syngas) fuels to power gas turbine engines. An important issue concerning these fuels is the potential for increased contaminate deposition that can inhibit cooling designs and expedite the material degradation of vital turbine components. The purpose of this study was to provide a detailed understanding of how contaminates deposit on the surface of a turbine vane with a Thermal barrier coating (TBC). The vane model used in this study was designed to match the Thermal behavior of real engine components by properly scaling the convective heat transfer coefficients as well as the Thermal conductivity of the vane wall. Four different film cooling configurations were studied: round holes, craters, a trench and a modified trench. The contaminates used in this study were small particles of paraffin wax that were sprayed into the mainstream flow of the wind tunnel. The wax particles modeled both the molten nature of contaminates in an engine as well as the particle trajectory by properly matching the expected range of Stokes number. This study found that the presence of film cooling significantly increased the accumulation of deposits. It was also found that the deposition behavior was strongly affected by the film cooling configuration that was used on the pressure side of the vane. The craters and trench performed the best in mitigating the accumulation of deposits immediately downstream of the film cooling configuration. In general, the presence of deposits reduced the film cooling performance on the surface of the TBC. However, the Additional Thermal Insulation provided by the deposits improved the cooling performance at the interface of the TBC and vane wall.Copyright © 2012 by ASME
F. Todd Davidson - One of the best experts on this subject based on the ideXlab platform.
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Realistic Trench Film Cooling With a Thermal Barrier Coating and Deposition
Journal of Turbomachinery, 2014Co-Authors: David A. Kistenmacher, F. Todd Davidson, David G. BogardAbstract:Thermal barrier coatings (TBC’s) see extensive use in high temperature gas turbines. However, little work has been done to experimentally characterize the combination of TBC and film cooling. The purpose of this study is to investigate the cooling performance of a Thermally conducting turbine vane with a realistic film cooling trench geometry embedded in TBC. Additionally, the effect of contaminant deposition on the realistic trench was studied. The trench is termed realistic because it takes into account probable manufacturing limitations. The vane model and TBC used for this study were designed to match the Thermal behavior of an actual gas turbine vane with TBC by properly scaling their convective heat transfer coefficients, Thermal conductivities, and characteristic length scales. This study built upon previously published results with various film cooling geometries consisting of round holes, craters, an ideal trench, and a novel trench. The previous study showed that large changes in blowing ratio resulted in negligible effects on cooling performance. Changes to film cooling geometry also resulted in minor effects on cooling performance. This study found that the realistic trench and an idealized trench perform similarly. However, the width of the realistic trench left the vane wall more exposed to mainstream temperatures, especially at lower film coolant flow rates. This study also found that the trench designs helped to mitigate deposition formation better than round holes; however, the realistic trench was more prone to deposition within the trench. The overall cooling effectiveness was similar for both trench designs and relatively unchanged from the pre-deposition performance while the overall cooling effectiveness for round holes increased due to the Additional Thermal Insulation offered by the unmitigated deposition.Copyright © 2013 by ASME
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A Study of Deposition on a Turbine Vane With a Thermal Barrier Coating and Various Film Cooling Geometries
Journal of Turbomachinery, 2013Co-Authors: F. Todd Davidson, David A. Kistenmacher, David G. BogardAbstract:Recent interest has been shown in using synthetic gaseous (syngas) fuels to power gas turbine engines. An important issue concerning these fuels is the potential for increased contaminant deposition that can inhibit cooling designs and expedite the material degradation of vital turbine components. The purpose of this study was to provide a detailed understanding of how contaminants deposit on the surface of a turbine vane with a Thermal barrier coating (TBC). The vane model used in this study was designed to match the Thermal behavior of real engine components by properly scaling the convective heat transfer coefficients as well as the Thermal conductivity of the vane wall. Four different film cooling configurations were studied: round holes, craters, a trench, and a modified trench. The contaminants used in this study were small particles of paraffin wax that were sprayed into the mainstream flow of the wind tunnel. The wax particles modeled both the molten nature of contaminants in an engine as well as the particle trajectory by properly matching the expected range of Stokes number. This study found that the presence of film cooling significantly increased the accumulation of deposits. It was also found that the deposition behavior was strongly affected by the film cooling configuration that was used on the pressure side of the vane. The craters and trench performed the best in mitigating the accumulation of deposits immediately downstream of the film cooling configuration. In general, the presence of deposits reduced the film cooling performance on the surface of the TBC. However, the Additional Thermal Insulation provided by the deposits improved the cooling performance at the interface of the TBC and vane wall.
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Realistic Trench Film Cooling With a Thermal Barrier Coating and Deposition
Volume 3B: Heat Transfer, 2013Co-Authors: David A. Kistenmacher, F. Todd Davidson, David G. BogardAbstract:Thermal barrier coatings (TBC’s) see extensive use in high temperature gas turbines. However, little work has been done to experimentally characterize the combination of TBC and film cooling. The purpose of this study is to investigate the cooling performance of a Thermally conducting turbine vane with a realistic film cooling trench geometry embedded in TBC. Additionally, the effect of contaminant deposition on the realistic trench was studied. The trench is termed realistic because it takes into account probable manufacturing limitations. The vane model and TBC used for this study were designed to match the Thermal behavior of an actual gas turbine vane with TBC by properly scaling their convective heat transfer coefficients, Thermal conductivities, and characteristic length scales. This study built upon previously published results with various film cooling geometries consisting of round holes, craters, an ideal trench, and a novel trench. The previous study showed that large changes in blowing ratio resulted in negligible effects on cooling performance. Changes to film cooling geometry also resulted in minor effects on cooling performance. This study found that the realistic trench and an idealized trench perform similarly. However, the width of the realistic trench left the vane wall more exposed to mainstream temperatures, especially at lower film coolant flow rates. This study also found that the trench designs helped to mitigate deposition formation better than round holes; however, the realistic trench was more prone to deposition within the trench. The overall cooling effectiveness was similar for both trench designs and relatively unchanged from the pre-deposition performance while the overall cooling effectiveness for round holes increased due to the Additional Thermal Insulation offered by the unmitigated deposition.
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A Study of Deposition on a Turbine Vane With a Thermal Barrier Coating and Various Film Cooling Geometries
Volume 4: Heat Transfer Parts A and B, 2012Co-Authors: F. Todd Davidson, David A. Kistenmacher, David G. BogardAbstract:Recent interest has been shown in using synthetic gaseous (syngas) fuels to power gas turbine engines. An important issue concerning these fuels is the potential for increased contaminate deposition that can inhibit cooling designs and expedite the material degradation of vital turbine components. The purpose of this study was to provide a detailed understanding of how contaminates deposit on the surface of a turbine vane with a Thermal barrier coating (TBC). The vane model used in this study was designed to match the Thermal behavior of real engine components by properly scaling the convective heat transfer coefficients as well as the Thermal conductivity of the vane wall. Four different film cooling configurations were studied: round holes, craters, a trench and a modified trench. The contaminates used in this study were small particles of paraffin wax that were sprayed into the mainstream flow of the wind tunnel. The wax particles modeled both the molten nature of contaminates in an engine as well as the particle trajectory by properly matching the expected range of Stokes number. This study found that the presence of film cooling significantly increased the accumulation of deposits. It was also found that the deposition behavior was strongly affected by the film cooling configuration that was used on the pressure side of the vane. The craters and trench performed the best in mitigating the accumulation of deposits immediately downstream of the film cooling configuration. In general, the presence of deposits reduced the film cooling performance on the surface of the TBC. However, the Additional Thermal Insulation provided by the deposits improved the cooling performance at the interface of the TBC and vane wall.Copyright © 2012 by ASME
David A. Kistenmacher - One of the best experts on this subject based on the ideXlab platform.
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Realistic Trench Film Cooling With a Thermal Barrier Coating and Deposition
Journal of Turbomachinery, 2014Co-Authors: David A. Kistenmacher, F. Todd Davidson, David G. BogardAbstract:Thermal barrier coatings (TBC’s) see extensive use in high temperature gas turbines. However, little work has been done to experimentally characterize the combination of TBC and film cooling. The purpose of this study is to investigate the cooling performance of a Thermally conducting turbine vane with a realistic film cooling trench geometry embedded in TBC. Additionally, the effect of contaminant deposition on the realistic trench was studied. The trench is termed realistic because it takes into account probable manufacturing limitations. The vane model and TBC used for this study were designed to match the Thermal behavior of an actual gas turbine vane with TBC by properly scaling their convective heat transfer coefficients, Thermal conductivities, and characteristic length scales. This study built upon previously published results with various film cooling geometries consisting of round holes, craters, an ideal trench, and a novel trench. The previous study showed that large changes in blowing ratio resulted in negligible effects on cooling performance. Changes to film cooling geometry also resulted in minor effects on cooling performance. This study found that the realistic trench and an idealized trench perform similarly. However, the width of the realistic trench left the vane wall more exposed to mainstream temperatures, especially at lower film coolant flow rates. This study also found that the trench designs helped to mitigate deposition formation better than round holes; however, the realistic trench was more prone to deposition within the trench. The overall cooling effectiveness was similar for both trench designs and relatively unchanged from the pre-deposition performance while the overall cooling effectiveness for round holes increased due to the Additional Thermal Insulation offered by the unmitigated deposition.Copyright © 2013 by ASME
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A Study of Deposition on a Turbine Vane With a Thermal Barrier Coating and Various Film Cooling Geometries
Journal of Turbomachinery, 2013Co-Authors: F. Todd Davidson, David A. Kistenmacher, David G. BogardAbstract:Recent interest has been shown in using synthetic gaseous (syngas) fuels to power gas turbine engines. An important issue concerning these fuels is the potential for increased contaminant deposition that can inhibit cooling designs and expedite the material degradation of vital turbine components. The purpose of this study was to provide a detailed understanding of how contaminants deposit on the surface of a turbine vane with a Thermal barrier coating (TBC). The vane model used in this study was designed to match the Thermal behavior of real engine components by properly scaling the convective heat transfer coefficients as well as the Thermal conductivity of the vane wall. Four different film cooling configurations were studied: round holes, craters, a trench, and a modified trench. The contaminants used in this study were small particles of paraffin wax that were sprayed into the mainstream flow of the wind tunnel. The wax particles modeled both the molten nature of contaminants in an engine as well as the particle trajectory by properly matching the expected range of Stokes number. This study found that the presence of film cooling significantly increased the accumulation of deposits. It was also found that the deposition behavior was strongly affected by the film cooling configuration that was used on the pressure side of the vane. The craters and trench performed the best in mitigating the accumulation of deposits immediately downstream of the film cooling configuration. In general, the presence of deposits reduced the film cooling performance on the surface of the TBC. However, the Additional Thermal Insulation provided by the deposits improved the cooling performance at the interface of the TBC and vane wall.
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Realistic Trench Film Cooling With a Thermal Barrier Coating and Deposition
Volume 3B: Heat Transfer, 2013Co-Authors: David A. Kistenmacher, F. Todd Davidson, David G. BogardAbstract:Thermal barrier coatings (TBC’s) see extensive use in high temperature gas turbines. However, little work has been done to experimentally characterize the combination of TBC and film cooling. The purpose of this study is to investigate the cooling performance of a Thermally conducting turbine vane with a realistic film cooling trench geometry embedded in TBC. Additionally, the effect of contaminant deposition on the realistic trench was studied. The trench is termed realistic because it takes into account probable manufacturing limitations. The vane model and TBC used for this study were designed to match the Thermal behavior of an actual gas turbine vane with TBC by properly scaling their convective heat transfer coefficients, Thermal conductivities, and characteristic length scales. This study built upon previously published results with various film cooling geometries consisting of round holes, craters, an ideal trench, and a novel trench. The previous study showed that large changes in blowing ratio resulted in negligible effects on cooling performance. Changes to film cooling geometry also resulted in minor effects on cooling performance. This study found that the realistic trench and an idealized trench perform similarly. However, the width of the realistic trench left the vane wall more exposed to mainstream temperatures, especially at lower film coolant flow rates. This study also found that the trench designs helped to mitigate deposition formation better than round holes; however, the realistic trench was more prone to deposition within the trench. The overall cooling effectiveness was similar for both trench designs and relatively unchanged from the pre-deposition performance while the overall cooling effectiveness for round holes increased due to the Additional Thermal Insulation offered by the unmitigated deposition.
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A Study of Deposition on a Turbine Vane With a Thermal Barrier Coating and Various Film Cooling Geometries
Volume 4: Heat Transfer Parts A and B, 2012Co-Authors: F. Todd Davidson, David A. Kistenmacher, David G. BogardAbstract:Recent interest has been shown in using synthetic gaseous (syngas) fuels to power gas turbine engines. An important issue concerning these fuels is the potential for increased contaminate deposition that can inhibit cooling designs and expedite the material degradation of vital turbine components. The purpose of this study was to provide a detailed understanding of how contaminates deposit on the surface of a turbine vane with a Thermal barrier coating (TBC). The vane model used in this study was designed to match the Thermal behavior of real engine components by properly scaling the convective heat transfer coefficients as well as the Thermal conductivity of the vane wall. Four different film cooling configurations were studied: round holes, craters, a trench and a modified trench. The contaminates used in this study were small particles of paraffin wax that were sprayed into the mainstream flow of the wind tunnel. The wax particles modeled both the molten nature of contaminates in an engine as well as the particle trajectory by properly matching the expected range of Stokes number. This study found that the presence of film cooling significantly increased the accumulation of deposits. It was also found that the deposition behavior was strongly affected by the film cooling configuration that was used on the pressure side of the vane. The craters and trench performed the best in mitigating the accumulation of deposits immediately downstream of the film cooling configuration. In general, the presence of deposits reduced the film cooling performance on the surface of the TBC. However, the Additional Thermal Insulation provided by the deposits improved the cooling performance at the interface of the TBC and vane wall.Copyright © 2012 by ASME
Harry Boyer - One of the best experts on this subject based on the ideXlab platform.
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Energy, cost, and CO 2 emission comparison between radiant wall panel systems and radiator systems
Energy and Buildings, 2012Co-Authors: Milorad Bojić, Dragan Cvetković, Marko Miletić, Jovan Malešević, Harry BoyerAbstract:The main goal of this paper is to evaluate the possibility of application or replacement of radiators with low-temperature radiant panels. This paper shows the comparison results of operations of 4 space heating systems: the low-temperature radiant panel system without any Additional Thermal Insulation of external walls (PH-WOI), the low-temperature radiant panel system with Additional Thermal Insulation of external walls (PH-WI), the radiator system without any Additional Thermal Insulation of external walls (the classical heating system) (RH-WOI), and the radiator system with Additional Thermal Insulation of external walls (RH-WI). The operation of each system is simulated by software EnergyPlus. The investigation shows that the PH-WI gives the best results. The RH-WOI has the largest energy consumption, and the largest pollutant emission. However, the PH-WI requires the highest investment.
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Energy, cost, and CO2 emission comparison between radiant wall panel systems and radiator systems
Energy and Buildings, 2012Co-Authors: Milorad Bojić, Dragan Cvetković, Marko Miletić, Jovan Malešević, Harry BoyerAbstract:The main goal of this paper is to evaluate the possibility of application or replacement of radiators with low-temperature radiant panels. This paper shows the comparison results of operations of 4 space heating systems: the low-temperature radiant panel system without any Additional Thermal Insulation of external walls (PH-WOI), the low-temperature radiant panel system with Additional Thermal Insulation of external walls (PH-WI), the radiator system without any Additional Thermal Insulation of external walls (the classical heating system) (RH-WOI), and the radiator system with Additional Thermal Insulation of external walls (RH-WI). The operation of each system is simulated by software EnergyPlus. The investigation shows that the PH-WI gives the best results. The RH-WOI has the largest energy consumption, and the largest pollutant emission. However, the PH-WI requires the highest investment.
Stefano Agnoli - One of the best experts on this subject based on the ideXlab platform.
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cool and green roofs an energy and comfort comparison between passive cooling and mitigation urban heat island techniques for residential buildings in the mediterranean region
Energy and Buildings, 2012Co-Authors: Michele Zinzi, Stefano AgnoliAbstract:Abstract The increase of peak and energy demand during the cooling season is becoming a crucial issue, as well as the intensification of the urban heat island effect. This trend is observed at several latitudes, including areas where overheating was unknown at building and urban levels. This phenomenon involves different issues: reduction of greenhouse gases, quality and comfort in outdoor and indoor environment, security of energy supply, public health. The building sector is directly involved in this change and adequate solutions can provide great benefit at energy and environmental levels. Roofs in particular are envelope components for which advanced solutions can provide significant energy savings in cooled buildings or improve indoor Thermal conditions in not cooled buildings. Cool materials keep the roof cool under the sun by reflecting the incident solar radiation away from the building and radiating the heat away at night. Roofs covered with vegetation take benefits of the Additional Thermal Insulation provided by the soil and of the evapo-transpiration to keep the roof cool under the sun. These two technologies are different in: structural requirements, initial and lifetime maintenance costs, impact on the overall energy performance of buildings. This paper presents a numerical comparative analysis between these solutions, taking into account the several parameters that affect the final energy performances. By means of dynamic simulations, the paper depicts how cool and green roofs can improve the energy performance of residential buildings in different localities at Mediterranean latitudes.
