Effects of Surface Deposition, Hole Blockage, and Thermal Barrier Coating Spallation on Vane Endwall Film Cooling

2006 ◽  
Vol 129 (3) ◽  
pp. 599-607 ◽  
Author(s):  
N. Sundaram ◽  
K. A. Thole
Keyword(s):  
Thermal Barrier Coating ◽  
Film Cooling ◽  
Gas Turbines ◽  
Large Scale ◽  
Leading Edge ◽  
Thermal Barrier ◽  
Cooling Effectiveness ◽  
Barrier Coating ◽  
Cooling Hole ◽  
Alternate Fuels

With the increase in usage of gas turbines for power generation and given that natural gas resources continue to be depleted, it has become increasingly important to search for alternate fuels. One source of alternate fuels is coal derived synthetic fuels. Coal derived fuels, however, contain traces of ash and other contaminants that can deposit on vane and turbine surfaces affecting their heat transfer through reduced film cooling. The endwall of a first stage vane is one such region that can be susceptible to depositions from these contaminants. This study uses a large-scale turbine vane cascade in which the following effects on film cooling adiabatic effectiveness were investigated in the endwall region: the effect of near-hole deposition, the effect of partial film cooling hole blockage, and the effect of spallation of a thermal barrier coating. The results indicated that deposits near the hole exit can sometimes improve the cooling effectiveness at the leading edge, but with increased deposition heights the cooling deteriorates. Partial hole blockage studies revealed that the cooling effectiveness deteriorates with increases in the number of blocked holes. Spallation studies showed that for a spalled endwall surface downstream of the leading edge cooling row, cooling effectiveness worsened with an increase in blowing ratio.

Effects of Surface Deposition, Hole Blockage, and TBC Spallation on Vane Endwall Film-Cooling

2006 ◽  
Author(s):  
N. Sundaram ◽  
K. A. Thole
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Large Scale ◽  
Leading Edge ◽  
Cooling Effectiveness ◽  
Blowing Ratio ◽  
Barrier Coating ◽  
Cooling Hole ◽  
Endwall Film Cooling ◽  
Alternate Fuels

With the increase in usage of gas turbines for power generation and given that natural gas resources continue to be depleted, it has become increasingly important to search for alternate fuels. One source of alternate fuels is coal derived synthetic fuels. Coal derived fuels, however, contain traces of ash and other contaminants that can deposit on vane and turbine surfaces affecting their heat transfer through reduced film-cooling. The endwall of a first stage vane is one such region that can be susceptible to depositions from these contaminants. This study uses a large-scale turbine vane cascade in which the following effects on film-cooling adiabatic effectiveness were investigated in the endwall region: the effect of near-hole deposition, the effect of partial film-cooling hole blockage, and the effect of spallation of a thermal barrier coating. The results indicated that deposits near the hole exit can sometimes improve the cooling effectiveness at the leading edge, but with increased deposition heights the cooling deteriorates. Partial hole blockage studies revealed that the cooling effectiveness deteriorates with increases in the number of blocked holes. Spallation studies showed that for a spalled endwall surface downstream of the leading edge cooling row, cooling effectiveness worsened with an increase in blowing ratio.

Thermal Analysis in a Film Cooling Hole with Thermal Barrier Coating

2009 ◽  
Vol 23 (4) ◽  
pp. 843-847 ◽  
Author(s):  
Dong Hyun Lee ◽  
Kyung Min Kim ◽  
Sangwoo Shin ◽  
Hyung Hee Cho
Keyword(s):  
Thermal Analysis ◽  
Thermal Barrier Coating ◽  
Film Cooling ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Cooling Hole

Effect of Thermal Barrier Coating and Gas Radiation on Film Cooling of a Corrugated Surface

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Kuldeep Singh ◽  
B. Premachandran ◽  
M. R. Ravi
Keyword(s):  
Mach Number ◽  
Thermal Barrier Coating ◽  
Film Cooling ◽  
Heat Transfer Analysis ◽  
Thermal Barrier ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Corrugated Surface ◽  
Gas Radiation ◽  
Barrier Coating

In this work, a numerical study is conducted to investigate film cooling of a corrugated surface. A conjugate heat transfer analysis is carried out, accounting for the presence of thermal barrier coating (TBC) and gas radiation. The Mach number of mainstream flow is maintained at Ma = 0.6, while cold stream Mach number is varied from 0.3 to 0.58, and density ratio is kept 4. From this study, it is observed that the overall film cooling effectiveness increases by a value ranging from 0.10 to 0.15 with the use of TBC. The hot side metallic wall temperature increases in the range of 100–150 °C when the effect of gas radiation is considered. It is also found that the film cooling effectiveness decreases with decrease in the cold side Mach number.

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.

Experimental Simulation of a Film Cooled Turbine Blade Leading Edge Including Thermal Barrier Coating Effects

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Jonathan Maikell ◽  
David Bogard ◽  
Justin Piggush ◽  
Atul Kohli
Keyword(s):  
Thermal Barrier Coating ◽  
Turbine Blade ◽  
Film Cooling ◽  
Leading Edge ◽  
Experimental Simulation ◽  
Thermal Barrier ◽  
Stagnation Line ◽  
Barrier Coating ◽  
Overall Effectiveness ◽  
Blade Leading Edge

For this study, a simulated film cooled turbine blade leading edge, constructed of a special high conductivity material, was used to determine the normalized “metal temperature” representative of actual engine conditions. The Biot number for the model was matched to that for operational engine conditions, ensuring that the normalized wall temperature, i.e., the overall effectiveness, was matched to that for the engine. Measurements of overall effectiveness were made for models with and without thermal barrier coating (TBC) at various operating conditions. This was the first study to experimentally simulate TBC and the effects on overall effectiveness. Two models were used: one with a single row of holes along the stagnation line, and the second with three rows of holes straddling the stagnation line. Film cooling was operated using a density ratio of 1.5 and for range of blowing ratios from M=0.5 to M=3.0. Both models were tested using a range of angles of attack from 0.0 deg to ±5.0 deg. As expected, the TBC coated models had significantly higher external surface temperatures, but lower metal temperatures. These experimental results provide a unique database for evaluating numerical simulations of the effects of TBC on leading edge film cooling performance.

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.

Experimental Simulation of a Film Cooled Turbine Blade Leading Edge Including Thermal Barrier Coating Effects

2009 ◽  
Author(s):  
Jonathan Maikell ◽  
David Bogard ◽  
Justin Piggush ◽  
Atul Kohli
Keyword(s):  
Thermal Barrier Coating ◽  
Turbine Blade ◽  
Film Cooling ◽  
Leading Edge ◽  
Experimental Simulation ◽  
Thermal Barrier ◽  
Stagnation Line ◽  
Barrier Coating ◽  
Overall Effectiveness ◽  
Blade Leading Edge

For this study a simulated film cooled turbine blade leading edge, constructed of a special high conductivity material, was used to determine the normalized “metal temperature” representative of actual engine conditions. The Biot number for the model was matched to that for operational engine conditions ensuring that the normalized wall temperature, i.e. the overall effectiveness, was matched to that for the engine. Measurements of overall effectiveness were made for models with and without TBC (thermal barrier coating) at various operating conditions. This was the first study to experimentally simulate TBC and the effects on overall effectiveness. Two models were used, one with a single row of holes along the stagnation line, and the second with three rows of holes straddling the stagnation line. Film cooling was operated using a density ratio of 1.5 and for range of blowing ratios from M = 0.5 to M = 3.0. Both models were tested using a range of angles of attack from 0.0 to ± 5.0 degrees. As expected, the TBC coated models had significantly higher external surface temperatures, but lower “metal temperatures.” These experimental results provide a unique database for evaluating numerical simulations of the effects of TBC on leading edge film cooling performance.

scholarly journals A Combustor Can With 1.8 mm Thick Plasma Sprayed Thermal Barrier Coating

1998 ◽  
Author(s):  
Jan Wigren ◽  
Jens Dahlin ◽  
Mats-Olov Hansson
Keyword(s):  
Thermal Barrier Coating ◽  
Film Cooling ◽  
Gas Turbines ◽  
Thermal Barrier ◽  
Current State ◽  
Barrier Coating ◽  
Component Test ◽  
Before And After ◽  
Plasma Sprayed ◽  
Cooling Air

The benefits of thermal barrier coatings for protection of combustor walls are well known. However, the trend to higher combustor inlet temperatures and the reduced availability of cooling air leads to a demand for better insulation performance from the thermal barrier coating (TBC). This is of particular benefit for low emission combustors where wall quenching effects need to be minimised and often hot side cooling is not permissible. A combustor can, for advanced stationary gas turbines, with 1.8 mm thick thermal barrier was designed and tested. The can was compared to a combustor can with a thermal barrier coating sprayed with current state-of-the-art methods, but to the same thickness. Steps to optimise performance were taken in all development stages. The design allowed easy spray geometries, improved edges and no film cooling. Spraying was optimised in order to achieve a segmented microstructure for reduction of stresses (by decrease of the Young’s Modulus in the coating) and increase compliance of the coating. Testing in component test rigs showed excellent results. The lifetime of the optimised combustor can was beyond test capabilities, whereas the reference combustor failed immediately. Metallographic and X-ray characterisation before and after component rig testing was performed and revealed features that explain the superiority of the segmented thermal barrier coating. This work has been funded by the CEC under the contract BRE-CT94-0936.

scholarly journals Progress in Novel Electrodeposited Bond Coats for Thermal Barrier Coating Systems

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4214
Author(s):  
Kranthi Kumar Maniam ◽  
Shiladitya Paul
Keyword(s):  
Gas Turbine ◽  
Thermal Barrier Coating ◽  
Gas Turbines ◽  
High Performance ◽  
Turbine Engines ◽  
Thermal Barrier ◽  
Gas Turbine Engines ◽  
Potential Cost ◽  
Bond Coats ◽  
Barrier Coating

The increased demand for high performance gas turbine engines has resulted in a continuous search for new base materials and coatings. With the significant developments in nickel-based superalloys, the quest for developments related to thermal barrier coating (TBC) systems is increasing rapidly and is considered a key area of research. Of key importance are the processing routes that can provide the required coating properties when applied on engine components with complex shapes, such as turbine vanes, blades, etc. Despite significant research and development in the coating systems, the scope of electrodeposition as a potential alternative to the conventional methods of producing bond coats has only been realised to a limited extent. Additionally, their effectiveness in prolonging the alloys’ lifetime is not well understood. This review summarises the work on electrodeposition as a coating development method for application in high temperature alloys for gas turbine engines and discusses the progress in the coatings that combine electrodeposition and other processes to achieve desired bond coats. The overall aim of this review is to emphasise the role of electrodeposition as a potential cost-effective alternative to produce bond coats. Besides, the developments in the electrodeposition of aluminium from ionic liquids for potential applications in gas turbines and the nuclear sector, as well as cost considerations and future challenges, are reviewed with the crucial raw materials’ current and future savings scenarios in mind.

Effects of Powder Morphology, Microstructure, and Residual Stresses on Thermal Barrier Coating Thermal Shock Performance

1996 ◽  
Author(s):  
J. Wigren ◽  
J.-F. de Vries ◽  
D. Greving
Keyword(s):  
Residual Stresses ◽  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Thermal Barrier ◽  
Spray Parameters ◽  
Powder Morphology ◽  
Barrier Coatings ◽  
Barrier Coating

Abstract Thermal barrier coatings are used in the aerospace industry for thermal insulation in hot sections of gas turbines. Improved coating reliability is a common goal among jet engine designers. In-service failures, such as coating cracking and spallation, result in decreased engine performance and costly maintenance time. A research program was conducted to evaluate residual stresses, microstructure, and thermal shock life of thermal barrier coatings produced from different powder types and spray parameters. Sixteen coatings were ranked according to their performance relative to the other coatings in each evaluation category. Comparisons of residual stresses, powder morphology, and microstructure to thermal shock life indicate a strong correlation to thermal barrier coating performance. Results from these evaluations will aid in the selection of an optimum thermal barrier coating system for turbine engine applications.

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