A Study of Deposition on a Turbine Vane With a Thermal Barrier Coating and Various Film Cooling Geometries

2012 ◽  
Author(s):  
F. Todd Davidson ◽  
David A. Kistenmacher ◽  
David G. Bogard
Keyword(s):  
Thermal Barrier Coating ◽  
Film Cooling ◽  
Stokes Number ◽  
Thermal Barrier ◽  
Transfer Coefficients ◽  
Cooling Performance ◽  
Heat Transfer Coefficients ◽  
Barrier Coating ◽  
Turbine Vane ◽  
Engine Components

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.

A Study of Deposition on a Turbine Vane With a Thermal Barrier Coating and Various Film Cooling Geometries

2013 ◽  
Vol 136 (4) ◽  
Author(s):  
F. Todd Davidson ◽  
David A. Kistenmacher ◽  
David G. Bogard
Keyword(s):  
Thermal Barrier Coating ◽  
Film Cooling ◽  
Stokes Number ◽  
Thermal Barrier ◽  
Transfer Coefficients ◽  
Cooling Performance ◽  
Heat Transfer Coefficients ◽  
Barrier Coating ◽  
Turbine Vane ◽  
Engine Components

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.

Realistic Trench Film Cooling With a Thermal Barrier Coating and Deposition

2013 ◽  
Author(s):  
David A. Kistenmacher ◽  
F. Todd Davidson ◽  
David G. Bogard
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Thermal Barrier ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Heat Transfer Coefficients ◽  
Barrier Coating ◽  
Turbine Vane ◽  
Thermally Conducting

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.

Realistic Trench Film Cooling With a Thermal Barrier Coating and Deposition

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
David A. Kistenmacher ◽  
F. Todd Davidson ◽  
David G. Bogard
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Thermal Barrier ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Heat Transfer Coefficients ◽  
Barrier Coating ◽  
Turbine Vane ◽  
Thermally Conducting

Thermal barrier coatings (TBC) 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 predeposition performance, while the overall cooling effectiveness for round holes increased due to the additional thermal insulation offered by the unmitigated deposition.

Film Cooling With a Thermal Barrier Coating: Round Holes, Craters, and Trenches

2013 ◽  
Vol 136 (4) ◽  
Author(s):  
F. Todd Davidson ◽  
David A. KistenMacher ◽  
David G. Bogard
Keyword(s):  
Thermal Behavior ◽  
Film Cooling ◽  
Thermal Protection ◽  
Engine Performance ◽  
Thermal Barrier ◽  
Transfer Coefficients ◽  
Cooling Performance ◽  
Barrier Coating ◽  
Internally Cooled ◽  
Thermally Conducting

Little work has been done to understand the interconnected nature of film cooling and thermal barrier coatings (TBCs) on protecting high temperature turbine components. With increasing demands for improved engine performance it is vital that a greater understanding of the thermal behavior of turbine components is achieved. The purpose of this study was to investigate how various film cooling geometries affect the cooling performance of a thermally conducting turbine vane with a 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 along with the thermal conductivity of the vane wall. This allowed for the measurement of temperatures at the interface of the TBC and vane wall which, when nondimensionalized, are representative of the temperatures present for actual engine vanes. This study found that the addition of a TBC on the surface of an internally cooled vane produced a near constant cooling performance despite significant changes in the blowing ratio. The craters, trench, and modified trench of this study were found to provide much better film cooling coverage than round holes; however, the improved film cooling coverage led to only slight improvements in temperature at the interface of the TBC and vane wall. These results suggest that there is minimal advantage in using more complicated cooling configurations, particularly since they may be more susceptible to TBC spallation. However, the improved film coverage from the trench and crater designs may increase the life of the TBC, which would be greatly beneficial to the long-term thermal protection of the vane.

Degradation of Film Cooling Performance on a Turbine Vane Suction Side due to Surface Roughness

2005 ◽  
Vol 128 (3) ◽  
pp. 547-554 ◽  
Author(s):  
James L. Rutledge ◽  
David Robertson ◽  
David G. Bogard
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Film Cooling ◽  
Extended Period ◽  
Suction Side ◽  
Transfer Coefficients ◽  
Cooling Performance ◽  
Heat Transfer Coefficients ◽  
Turbine Vane ◽  
Adiabatic Effectiveness

After an extended period of operation, the surfaces of turbine airfoils become extremely rough due to deposition, spallation, and erosion. The rough airfoil surfaces will cause film cooling performance degradation due to effects on adiabatic effectiveness and heat transfer coefficients. In this study, the individual and combined effects of roughness upstream and downstream of a row of film cooling holes on the suction side of a turbine vane have been determined. Adiabatic effectiveness and heat transfer coefficients were measured for a range of mainstream turbulence levels and with and without showerhead blowing. Using these parameters, the ultimate film cooling performance was quantified in terms of net heat flux reduction. The dominant effect of roughness was a doubling of the heat transfer coefficients. Maximum adiabatic effectiveness levels were also decreased significantly. Relative to a film cooled smooth surface, a film cooled rough surface was found to increase the heat flux to the surface by 30%–70%.

Film Cooling With a Thermal Barrier Coating: Round Holes, Craters and Trenches

2012 ◽  
Author(s):  
F. Todd Davidson ◽  
David A. Kistenmacher ◽  
David G. Bogard
Keyword(s):  
Thermal Behavior ◽  
Film Cooling ◽  
Thermal Protection ◽  
Engine Performance ◽  
Thermal Barrier ◽  
Transfer Coefficients ◽  
Cooling Performance ◽  
Barrier Coating ◽  
Internally Cooled ◽  
Thermally Conducting

Little work has been done to understand the interconnected nature of film cooling and thermal barrier coatings (TBC’s) on protecting high temperature turbine components. With increasing demands for improved engine performance it is vital that a greater understanding of the thermal behavior of turbine components is achieved. The purpose of this study was to investigate how various film cooling geometries affect the cooling performance of a thermally conducting turbine vane with a 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. This allowed for the measurement of temperatures at the interface of the TBC and vane wall which, when non-dimensionalized, are representative of the temperatures present for actual engine vanes. This study found that the addition of TBC on the surface of an internally cooled vane produced a near constant cooling performance despite significant changes in the blowing ratio. The craters, trench and modified trench of this study were found to provide much better film cooling coverage than round holes; however, the improved film cooling coverage led to only slight improvements in temperature at the interface of the TBC and vane wall. These results suggest that there is minimal advantage in using more complicated cooling configurations, particularly since they may be more susceptible to TBC spallation. However, the improved film coverage from the trench and crater designs may increase the life of the TBC which would be greatly beneficial to the long-term thermal protection of the vane.

Degradation of Film Cooling Performance on a Turbine Vane Suction Side Due to Surface Roughness

2005 ◽  
Author(s):  
James L. Rutledge ◽  
David Robertson ◽  
David G. Bogard
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Film Cooling ◽  
Extended Period ◽  
Suction Side ◽  
Transfer Coefficients ◽  
Cooling Performance ◽  
Heat Transfer Coefficients ◽  
Turbine Vane ◽  
Adiabatic Effectiveness

After an extended period of operation, the surfaces of turbine airfoils become extremely rough due to deposition, spallation, and erosion. The rough airfoil surfaces will cause film cooling performance degradation due to effects on adiabatic effectiveness and heat transfer coefficients. In this study, the individual and combined effects of roughness upstream and downstream of a row of film cooling holes on the suction side of a turbine vane have been determined. Adiabatic effectiveness and heat transfer coefficients were measured for a range of mainstream turbulence levels and with and without showerhead blowing. Using these parameters, the ultimate film cooling performance was quantified in terms of net heat flux reduction. The dominant effect of roughness was a doubling of the heat transfer coefficients. Maximum adiabatic effectiveness levels were also decreased significantly. Relative to a film cooled smooth surface, a film cooled rough surface was found to increase the heat flux to the surface by 30% to 70%.

Experimental and Numerical Study on the Effects of the Relative Position of Film Hole and Orientation Ribs on the Film Cooling With Ribbed Cross-Flow Coolant Channel

2020 ◽  
Author(s):  
Bingran Li ◽  
Cunliang Liu ◽  
Lin Ye ◽  
Huiren Zhu ◽  
Fan Zhang
Keyword(s):  
Heat Transfer ◽  
Relative Position ◽  
Film Cooling ◽  
Numerical Study ◽  
Cross Flow ◽  
Internal Cooling ◽  
Transfer Coefficients ◽  
Cooling Performance ◽  
Heat Transfer Coefficients ◽  
Numerical Studies

Abstract To investigate the application of ribbed cross-flow coolant channels with film hole effusion and the effects of the internal cooling configuration on film cooling, experimental and numerical studies are conducted on the effect of the relative position of the film holes and different orientation ribs on the film cooling performance. Three cases of the relative position of the film holes and different orientation ribs (post-rib, centered, and pre-rib) in two ribbed cross-flow channels (135° and 45° orientation ribs) are investigated. The film cooling performances are measured under three blowing ratios by the transient liquid crystal measurement technique. A RANS simulation with the realizable k-ε turbulence model and enhanced wall treatment is performed. The results show that the cooling effectiveness and the downstream heat transfer coefficient for the 135° rib are basically the same in the three position cases, and the differences between the local effectiveness average values for the three are no more than 0.04. The differences between the heat transfer coefficients are no more than 0.1. The “pre-rib” and “centered” cases are studied for the 45° rib, and the position of the structures has little effect on the film cooling performance. In the different position cases, the outlet velocity distribution of the film holes, the jet pattern and the discharge coefficient are consistent with the variation in the cross flow. The related research previously published by the authors showed that the inclination of the ribs with respect to the holes affects the film cooling performance. This study reveals that the relative positions of the ribs and holes have little effect on the film cooling performance. This paper expands and improves the study of the effect of the internal cooling configuration on film cooling and makes a significant contribution to the design and industrial application of the internal cooling channel of a turbine blade.

Heat Transfer Coefficient Measurements of Film-Cooling Holes With Expanded Exits

1998 ◽  
Author(s):  
M. Gritsch ◽  
A. Schulz ◽  
S. Wittig
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Film Cooling ◽  
Cylindrical Hole ◽  
Superposition Method ◽  
Transfer Coefficients ◽  
Cooling Performance ◽  
Heat Transfer Coefficients ◽  
Film Cooling Holes ◽  
Injection Location

Detailed measurements of heat transfer coefficients in the nearfield of three different film-cooling holes are presented. The hole geometries investigated include a cylindrical hole and two holes with a diffuser shaped exit portion (i.e. a fan-shaped and a laidback fanshaped hole). They were tested over a range of blowing ratios M = 0.25…1.75 at an external crossflow Mach number of 0.6 and a coolant-to-mainflow density ratio of 1.85. Additionally, the effect of the internal coolant supply Mach number is addressed. Temperatures of the diabatic surface downstream of the injection location are measured by means of an infrared camera system. They are used as boundary conditions for a finite element analysis to determine surface heat fluxes and heat transfer coefficients. The superposition method is applied to evaluate the overall film-cooling performance of the hole geometries investigated. As compared to the cylindrical hole, both expanded holes show significantly lower heat transfer coefficients downstream of the injection location, particularly at high blowing ratios. The laidback fanshaped hole provides a better lateral spreading of the injected coolant than the fanshaped hole which leads to lower laterally averaged heat transfer coefficients. Coolant passage crossflow Mach number affects the flowfield of the jet being ejected from the hole and, therefore, has an important impact on film-cooling performance.

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