Scaling of Performance for Varying Density Ratio Coolants on an Airfoil With Strong Curvature and Pressure Gradient Effects

Ethridge, Marcia I.; Cutbirth, J. Michael; Bogard, David G.

doi:10.1115/1.1343457

Cited by 82 publications

(12 citation statements)

References 20 publications

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“…The distributions of η were similar for both DRs, but the DR = 1.8 coolant had a peak film effectiveness ofη = 0.38, whereas for DR = 1.2 the peak was η = 0.32. This may be attributed to better lateral distribution of the high-density coolant as noted by Sinha et al 12 Scaling of film effectiveness performance on simulated turbine airfoils was investigated by Cutbirth and Bogard 13 for the showerhead and pressure side of a vane, and by Ethridge et al 14 for the suction side of a vane. Showerhead cooling for low and high mainstream turbulence levels, T u = 0.5% and 20% respectively, was studied by Cutbirth and Bogard 13 for coolant DR = 1.2 and 1.8.…”

Section: Scaling Of Film-cooling Performance With Varying Drmentioning

confidence: 96%

Gas Turbine Film Cooling

Bogard

Thole

2006

Journal of Propulsion and Power

670

179

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The durability of gas turbine engines is strongly dependent on the component temperatures. For the combustor and turbine airfoils and endwalls, film cooling is used extensively to reduce component temperatures. Film cooling is a cooling method used in virtually all of today's aircraft turbine engines and in many power-generation turbine engines and yet has very difficult phenomena to predict. The interaction of jets-in-crossflow, which is representative of film cooling, results in a shear layer that leads to mixing and a decay in the cooling performance along a surface. This interaction is highly dependent on the jet-to-crossflow mass and momentum flux ratios. Film-cooling performance is difficult to predict because of the inherent complex flowfields along the airfoil component surfaces in turbine engines. Film cooling is applied to nearly all of the external surfaces associated with the airfoils that are exposed to the hot combustion gasses such as the leading edges, main bodies, blade tips, and endwalls. In a review of the literature, it was found that there are strong effects of freestream turbulence, surface curvature, and hole shape on the performance of film cooling. Film cooling is reviewed through a discussion of the analyses methodologies, a physical description, and the various influences on film-cooling performance. Dr. David Bogard is a Professor of Mechanical Engineering at the University of Texas at Austin, and holds the John E. Kasch Fellow in Engineering. He received his B.S. and M.S. degrees in mechanical engineering from Oklahoma State University, and his Ph.D. from Purdue University. He has served on the faculty at the University of Texas since 1982. Dr. Bogard has been active in gas turbine cooling research since 1986, and has published over 100 peer-reviewed papers. He was awarded the ASME Heat Transfer Committee Best Paper Award in 1990 and 2003, and is a fellow of the ASME. Dr. Karen Thole holds the William S. Cross Professorship of Mechanical Engineering at Virginia Polytechnic Institute and State University. She received her B.S. and M.S. degrees in mechanical engineering from the University of Illinois, and a Ph.D. from the University of Texas at Austin. She spent two years as a postdoctoral researcher at the Institute for Thermal Turbomachinery at the University of Karslruhe in Germany and in 1994 she accepted a faculty position at the University of Wisconsin-Madison. In 1999, she became a faculty member in the Mechanical Engineering Department at Virginia Polytechnic Institute and State University where she was promoted to professor in 2003. She received the National Science Foundation CAREER Award in 1996, which was directed at developing a better understanding of gas turbine heat transfer. Dr. Thole's areas of expertise are heat transfer and fluid mechanics specializing in turbulent boundary layers, convective heat transfer, and high freestream turbulence effects. She has published more than 80 peer-reviewed papers and has advised over 30 graduate theses.

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Section: Scaling Of Film-cooling Performance With Varying Drmentioning

confidence: 96%

Gas Turbine Film Cooling

Bogard

Thole

2006

Journal of Propulsion and Power

670

179

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“…The adiabatic effectiveness was corrected for 1D conduction through the wall using the following equation, after Ethridge et al [10]:…”

Section: Experimental Facilities and Proceduresmentioning

confidence: 99%

Evaluation of Superposition Predictions for Showerhead Film Cooling on a Vane

Anderson

Winka

Bogard

et al. 2015

Journal of Turbomachinery

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The leading edge of a turbine vane is subject to some of the highest temperature loading within an engine, and an accurate understanding of leading edge film coolant behavior is essential for modern engine design. Although there have been many investigations of the adiabatic effectiveness for showerhead film cooling of a vane leading edge region, there have been no previous studies in which individual rows of the showerhead were tested with the explicit intent of validating superposition models. For the current investigation, a series of adiabatic effectiveness experiments were performed with a five-row and threerow showerhead. The experiments were repeated separately with each individual row of holes active. This allowed evaluation of superposition methods on both the suction side of the vane, which was moderately convex, and the pressure side of the vane, which was mildly concave. Superposition was found to accurately predict performance on the suction side of the vane at lower momentum flux ratios, but not at higher momentum flux ratios. On the pressure side of the vane, the superposition predictions were consistently lower than measured values, with significant errors occurring at the higher momentum flux ratios. Reasons for the underprediction by superposition analysis are presented.

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“…However, the curvature of the concave surface results in a reattachment of the lifted-off coolant on the pressure side, resulting in higher downstream effectiveness. Ethridge et al (2001) studied the effect of coolant-to-mainstream density ratio on a vane with high curvature. Dittmar et al (2002) studied different film cooling hole configurations on the suction (convex) side and concluded that shaped holes provide better coverage at higher blowing ratios by resisting jet penetration into the mainstream.…”

Section: Blade Surface Film Coolingmentioning

confidence: 99%

Turbine Blade Film Cooling Using PSP Technique

Han¹,

Rallabandi²

2010

Frontiers in Heat and Mass Transfer

192

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Film cooling is widely used to protect modern gas turbine blades and vanes from the ever increasing inlet temperatures. Film cooling involves a very complex turbulent flow-field, the characterization of which is necessary for reliable and economical design. Several experimental studies have focused on gas turbine blade, vane and end-wall film cooling over the past few decades. Measurements of heat transfer coefficients, film cooling effectiveness values and heat flux ratios using several different experimental methods have been reported. The emphasis of this current review is on the Pressure Sensitive Paint (PSP) mass transfer analogy to determine the film cooling effectiveness. The theoretical basis of the method is presented in detail. Important results in the open literature obtained using the PSP method are presented, discussing parametric effects of blowing ratio, momentum ratio, density ratio, hole shape, surface geometry, free-stream turbulence on flat plates, turbine blades, vanes and end-walls. The PSP method provides very high resolution contours of film cooling effectiveness, without being subject to the conduction error in high thermal gradient regions near the hole.

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Scaling of Performance for Varying Density Ratio Coolants on an Airfoil With Strong Curvature and Pressure Gradient Effects

Cited by 82 publications

References 20 publications

Gas Turbine Film Cooling

Gas Turbine Film Cooling

Evaluation of Superposition Predictions for Showerhead Film Cooling on a Vane

Turbine Blade Film Cooling Using PSP Technique

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