Blockage Effects From Simulated Thermal Barrier Coatings for Cylindrical and Shaped Cooling Holes

Whitfield, Christopher A.; Schroeder, Robert P.; Thole, Karen A.; Lewis, Scott

doi:10.1115/1.4029879

Cited by 30 publications

(2 citation statements)

References 11 publications

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“…Also shown on Fig. 4 is data from Whitfield et al [30] who examined C d for a larger-scale, smooth film cooling hole of the same shape in a low-speed wind tunnel. Theirs is the only paper that has previously characterized flow through this hole shape.…”

Section: Resultsmentioning

confidence: 99%

Effects of Coolant Feed Direction on Additively Manufactured Film Cooling Holes

Stimpson

Snyder

Thole

et al. 2018

Journal of Turbomachinery

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Gas turbine components subjected to high temperatures can benefit from improved designs enabled by metal additive manufacturing (AM) with nickel alloys. Previous studies have shown that the impact on fluid flow and heat transfer resulting from surface roughness of additively manufactured parts is significant; these impacts must be understood to design turbine components successfully for AM. This study improves understanding of these impacts by examining the discharge coefficient and the effect of the coolant delivery direction on the performance of additively manufactured shaped film cooling holes. To accomplish this, five test coupons containing a row of baseline shaped film cooling holes were made from a high-temperature nickel alloy using a laser powder bed fusion (L-PBF) process. Flow and pressure drop measurements across the holes were collected to determine the discharge coefficient from the film cooling holes. Temperature measurements were collected to assess the overall effectiveness of the coupon surface as well as the cooling enhancement due to film cooling. The Biot number of the coupon wall was matched to a value one might find in a turbine engine to ensure this data is relevant. It was discovered that the flow experienced greater aerodynamic losses in film cooling holes with greater relative roughness, which resulted in a decreased discharge coefficient. The effectiveness measurements showed that the film cooling performance is better when coolant is fed in a co-flow configuration compared to a counter-flow configuration.

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Section: Resultsmentioning

confidence: 99%

Effects of Coolant Feed Direction on Additively Manufactured Film Cooling Holes

Stimpson

Snyder

Thole

et al. 2018

Journal of Turbomachinery

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“…Ronald et al [15] indicated that in comparison with cylindrical holes, shaped holes can better resistant to partial holeblockage. Christopher et al [16] blocked film holes with a low conductivity material to simulate the partial blockage of cylindrical and shaped holes caused by TBC spallation. Their experiment indicated that at low BRs, the blockages of shaped hole have very little effect on adiabatic film effectiveness, but at high BRs, the film effectiveness of shaped and cylindrical holes was decreased about 75% by hole-blockage.…”

Section: Introductionmentioning

confidence: 99%

Combined Influence of Surface Deposition and Hole-Blockage on Film-Cooling Performances

Wang

Yuan

et al. 2016

Volume 5C: Heat Transfer

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Commercial aero-engines may operate in dust-laden environments, such as taking off and landing on desert ground or flying through volcano dust cloud, and foreign particles frequently deposit at hot surface and film hole-exits, which results in partial blockage of film holes, clog of cooling air, reduction in cooling effect, and could induce catastrophic damage. This problem has not been well solved up to now. This paper presents an experimental investigation on two surface deposition models (deposition limited to upstream of hole with a peak height of 1.5 diameter of hole called D1.5, and downstream forming a trench with a peak height of 1.0 diameter of hole, called D1) and two blockage models (leading edge of hole LB, and trailing edge TB), as well as two combined models D1.5-LB, and D1-TB. The experiments are conducted in a low speed water tunnel using Planar Laser Induced Fluorescence (PLIF) technique. Through this experiment, the following interesting phenomena, which were not reported in previous literatures, are reveled: 1) The effect of blockage ratio at leading edge on cooling performance of combined D1.5-LB is opposite to individual LB, i.e. in the case of combined D1.5-LB, a higher blockage ratio corresponds to a lower cooling effectiveness; whereas, for individual LB, the cooling effectiveness increases with the blockage ratios in the tested range. 2) At all blowing ratios, the cooling performances of combined D1.5-LB are better than that of perfect model D0-B0 (without deposition and blockage). At all blockage ratios tested in this experiment, in the case of combined D1.5-LB, a higher blowing ratio corresponds to a higher cooling effectiveness and a lager film coverage length. 3) At lower blockage ratios of 0.1 and 0.3, the overall-averaged cooling effectiveness of combined D1-TB is higher than that of perfect model D0-B0. At large blockage ratio 0.5, the blockage effect is dominant, and the averaged cooling effectiveness of combined model D1-TB is lower than that of D0-B0. In the case of individual deposition model D1-B0, although the lateral-averaged film cooling effectiveness is augmented, the area of film cooling is reduced.

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