Sensitivity of the Overall Effectiveness to Film Cooling and Internal Cooling on a Turbine Vane Suction Side

2012 ◽  
Author(s):  
Randall P. Williams ◽  
Thomas E. Dyson ◽  
David G. Bogard ◽  
Sean D. Bradshaw
Keyword(s):  
Film Cooling ◽  
Momentum Flux ◽  
Suction Side ◽  
Coolant Temperature ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
Impingement Cooling ◽  
Turbine Vane ◽  
Cooling Effects ◽  
Engine Components

The overall cooling effectiveness for a turbine airfoil was quantified based on the external surface temperature relative to the mainstream temperature and the inlet coolant temperature. This can be determined experimentally when the model is constructed so that the Biot number is similar to that of engine components. In this study, the overall cooling effectiveness was experimentally measured on a model turbine vane constructed of a material deigned to match Bi for engine conditions. The model incorporated an internal impingement cooling configuration. Overall cooling effectiveness and adiabatic film effectiveness were measured downstream of a single row of round holes positioned on the suction side of the vane. Experiments were conducted to evaluate the cooling effects of internal cooling alone, and then the combined effects of film cooling and internal cooling for a range of coolant flow rates. While the adiabatic film effectiveness decreased when using high momentum flux ratios for the film cooling, due to coolant jet separation, the overall cooling effectiveness increased at higher momentum flux ratios. This increase was due to increased internal cooling effects. Overall cooling effectiveness measurements were also compared to analytical predictions based on a 1D thermal analysis using measured adiabatic film effectiveness and overall cooling effectiveness without film cooling.

Sensitivity of the Overall Effectiveness to Film Cooling and Internal Cooling on a Turbine Vane Suction Side

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
Randall P. Williams ◽  
Thomas E. Dyson ◽  
David G. Bogard ◽  
Sean D. Bradshaw
Keyword(s):  
Film Cooling ◽  
Momentum Flux ◽  
Suction Side ◽  
Coolant Temperature ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
Impingement Cooling ◽  
Turbine Vane ◽  
Cooling Effects ◽  
Engine Components

The overall cooling effectiveness for a turbine airfoil was quantified based on the external surface temperature relative to the mainstream temperature and the inlet coolant temperature. This can be determined experimentally when the model is constructed so that the Biot number is similar to that of engine components. In this study, the overall cooling effectiveness was experimentally measured on a model turbine vane constructed of a material deigned to match Bi for engine conditions. The model incorporated an internal impingement cooling configuration. Overall cooling effectiveness and adiabatic film effectiveness were measured downstream of a single row of round holes positioned on the suction side of the vane. Experiments were conducted to evaluate the cooling effects of internal cooling alone, and then the combined effects of film cooling and internal cooling for a range of coolant flow rates. While the adiabatic film effectiveness decreased when using high momentum flux ratios for the film cooling, due to coolant jet separation, the overall cooling effectiveness increased at higher momentum flux ratios. This increase was due to increased internal cooling effects. Overall cooling effectiveness measurements were also compared to analytical predictions based on a 1D thermal analysis using measured adiabatic film effectiveness and overall cooling effectiveness without film cooling.

Adiabatic and Overall Effectiveness for the Showerhead Film Cooling of a Turbine Vane

2012 ◽  
Author(s):  
Marc L. Nathan ◽  
Thomas E. Dyson ◽  
David G. Bogard ◽  
Sean D. Bradshaw
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Internal Heat ◽  
Flux Ratio ◽  
Coolant Temperature ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
Turbine Vane ◽  
Engine Components ◽  
Overall Effectiveness

There have been a number of previous studies of the adiabatic film effectiveness for the showerhead region of a turbine vane, but no previous studies of the overall cooling effectiveness. The overall cooling effectiveness is a measure of the external surface temperature relative to the mainstream temperature and the inlet coolant temperature, and consequently is a direct measure of how effectively the surface is cooled. This can be determined experimentally when the model is constructed so that the Biot number is similar to that of engine components, and the internal cooling is designed so that the ratio of the external to internal heat transfer coefficient is matched to that of the engine. In this study, the overall effectiveness was experimentally measured on a model turbine vane constructed of a material to match Bi for engine conditions. The model incorporated an internal impingement cooling configuration. The cooling design consisted of a showerhead composed of five rows of holes with one additional row on both pressure and suction sides of the vane. An identical model was also constructed out of low conductivity foam to measure adiabatic film effectiveness. Of particular interest in this study was to use the overall cooling effectiveness measurements to identify local hot spots which might lead to failure of the vane. Furthermore, the experimental measurements provided an important database for evaluation of CFD simulations of the conjugate heat transfer effects that occur in the showerhead region. Continuous improvement in both measures of performance was demonstrated with increasing momentum flux ratio.

Experimental Study on Analogy Principle of Overall Cooling Effectiveness for Composite Cooling Structures With Both Internal Cooling and Film Cooling

2019 ◽  
Author(s):  
Gang Xie ◽  
Cun-liang Liu ◽  
Rui Wang ◽  
Lin Ye ◽  
Jiajia Niu
Keyword(s):  
Film Cooling ◽  
Momentum Flux ◽  
Flux Ratio ◽  
Theoretical Work ◽  
Maximum Deviation ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
Impingement Cooling ◽  
Staggered Arrangement ◽  
Cooling Model

Abstract The previous theoretical work showed the matching principles of analogy parameters for effusion-impingement cooling model. The mismatch of temperature ratios Tg/Tc may result in different matching performance in laboratory condition. Thus, the analogy principles of overall cooling effectiveness were evaluated by experiments in different laboratory conditions for effusion-impingement cooling model. The film plate had 8 rows of cylinder film holes with staggered arrangement and the impingement holes was also employed staggered pattern. Four kinds of cases with different temperature ratios, varied from 1.1 to 2, were tested under three momentum flux ratios and corresponding blowing ratios. The 2D contours of overall cooling effectiveness were measured by using IR thermography. The results for cases with the same mainstream side Biot number and momentum flux ratio show similar contours and values of overall cooling effectiveness, although temperature ratios of these cases are different. And the maximum deviation of overall cooling effectiveness is within 0.02 for these cases. However, there were 0.04∼0.08 difference in the overall cooling effectiveness when the blowing ratios were matched. The overall cooling effectiveness significantly decreases under each blowing ratios with the increase of temperature ratios.

Adiabatic and Overall Effectiveness for a Fully Cooled Turbine Vane

2013 ◽  
Author(s):  
Thomas E. Dyson ◽  
John W. McClintic ◽  
David G. Bogard ◽  
Sean D. Bradshaw
Keyword(s):  
Biot Number ◽  
Film Cooling ◽  
Large Scale ◽  
Internal Heat ◽  
Coolant Temperature ◽  
Internal Cooling ◽  
Impingement Cooling ◽  
Turbine Vane ◽  
Cooling Design ◽  
Overall Effectiveness

Adiabatic and overall effectiveness data were measured for a fully cooled, scaled up turbine vane model in a low speed linear cascade with a chord-exit Reynolds number of 700,000. The overall effectiveness is a measure of the external surface temperature relative to the mainstream temperature and the inlet coolant temperature, and consequently is a direct measure of how effectively the surface is cooled. This can be determined experimentally when the experimental model is constructed so that the Biot number of the model and the ratio of the external to internal heat transfer coefficient are chosen so that the model has a similar thermal behavior to that of an actual engine component. The model used in this study had a cooling design that consisted of 149 total coolant holes in 13 rows, including a showerhead containing five rows of holes. The model also incorporated an internal impingement cooling configuration. An identical model was also constructed out of low conductivity foam to measure adiabatic effectiveness. This is the first study to use a large scale, matched Biot number model to measure engine representative overall effectiveness for a vane employing full coverage film cooling. The focus of this research was to determine the relative contributions of the external and internal cooling, and to serve as a baseline for validation of computational simulations. Additionally, a simplified model using measurements of overall effectiveness with internal cooling alone was used to predict overall effectiveness downstream of the showerhead.

Adiabatic and Overall Effectiveness for the Showerhead Film Cooling of a Turbine Vane

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
Marc L. Nathan ◽  
Thomas E. Dyson ◽  
David G. Bogard ◽  
Sean D. Bradshaw
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Internal Heat ◽  
Flux Ratio ◽  
Coolant Temperature ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
Turbine Vane ◽  
Dynamics Simulations ◽  
Overall Effectiveness

There have been a number of previous studies of the adiabatic film effectiveness for the showerhead region of a turbine vane, but no previous studies of the overall cooling effectiveness. The overall cooling effectiveness is a measure of the external surface temperature relative to the mainstream temperature and the inlet coolant temperature, and consequently is a direct measure of how effectively the surface is cooled. This can be determined experimentally when the model is constructed so that the Biot number is similar to that of engine components, and the internal cooling is designed so that the ratio of the external to internal heat transfer coefficient is matched to that of the engine. In this study, the overall effectiveness was experimentally measured on a model turbine vane constructed of a material to match Bi for engine conditions. The model incorporated an internal impingement cooling configuration. The cooling design consisted of a showerhead composed of five rows of holes with one additional row on both pressure and suction sides of the vane. An identical model was also constructed out of low conductivity foam to measure adiabatic film effectiveness. Of particular interest in this study was to use the overall cooling effectiveness measurements to identify local hot spots which might lead to failure of the vane. Furthermore, the experimental measurements provided an important database for evaluation of computational fluid dynamics simulations of the conjugate heat transfer effects that occur in the showerhead region. Continuous improvement in both measures of performance was demonstrated with increasing momentum flux ratio.

Film Cooling Effectiveness of Transonic Turbine Vane Suction Side With Compound-Angle Shaped Hole Configuration

2015 ◽  
Author(s):  
Shang-Feng Yang ◽  
Je-Chin Han ◽  
Alexander MirzaMoghadam ◽  
Ardeshir Riahi
Keyword(s):  
Transonic Flow ◽  
Film Cooling ◽  
Surface Film ◽  
Density Ratio ◽  
Suction Side ◽  
Flow Loop ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Turbine Vane ◽  
Compound Angle

This paper studies the effect of transonic flow velocity on local film cooling effectiveness distribution of turbine vane suction side, experimentally. A conduction-free Pressure Sensitive Paint (PSP) method is used to determine the local film cooling effectiveness. Tests were performed in a five-vane annular cascade at Texas A&M Turbomachinery laboratory blow-down flow loop facility. The exit Mach numbers are controlled to be 0.7, 0.9, and 1.1, from subsonic to transonic flow conditions. Three foreign gases N2, CO2 and Argon/SF6 mixture are selected to study the effects of three coolant-to-mainstream density ratios, 1.0, 1.5, and 2.0 on film cooling. Four averaged coolant blowing ratios in the range, 0.7, 1.0, 1.3 and 1.6 are investigated. The test vane features 3 rows of radial-angle cylindrical holes around the leading edge, and 2 rows of compound-angle shaped holes on the suction side. Results suggest that the PSP technique is capable of producing clear and detailed film cooling effectiveness contours at transonic condition. The effects of coolant to mainstream blowing ratio, density ratio, and exit Mach number on the vane suction-surface film cooling distribution are obtained, and the consequence results are presented and explained in this investigation.

Evaluation of Superposition Predictions for Showerhead Film Cooling on a Vane

2014 ◽  
Author(s):  
Joshua B. Anderson ◽  
James R. Winka ◽  
David G. Bogard ◽  
Michael E. Crawford
Keyword(s):  
Film Cooling ◽  
Momentum Flux ◽  
Leading Edge ◽  
Suction Side ◽  
Pressure Side ◽  
Edge Region ◽  
Current Investigation ◽  
Engine Design ◽  
Turbine Vane ◽  
Adiabatic Effectiveness

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 three-row 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 under-prediction by superposition analysis are presented.

Effects of Obstructions and Surface Roughness on Film Cooling Effectiveness With and Without a Transverse Trench

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Ruwan P. Somawardhana ◽  
David G. Bogard
Keyword(s):  
Surface Roughness ◽  
Film Cooling ◽  
Suction Side ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Surface Conditions ◽  
Turbine Vane ◽  
Cylindrical Holes ◽  
Better Than

Recent studies have shown that film cooling with holes embedded in a shallow trench significantly improves cooling performance. In this study, the performance of shallow trench configurations was investigated for simulated deteriorated surface conditions, i.e., increased surface roughness and near-hole obstructions. Experiments were conducted on the suction side of a scaled-up simulated turbine vane. Results from the study indicated that as much as 50% degradation occurred with upstream obstructions, but downstream obstructions actually enhanced film cooling effectiveness. However, the transverse trench configuration performed significantly better than the traditional cylindrical holes, both with and without obstructions and almost eliminated the effects of both surface roughness and obstructions.

Influence of Coolant Density on Turbine Blade Film-Cooling With Compound-Angle Shaped Holes

2012 ◽  
Author(s):  
Kevin Liu ◽  
Shang-Feng Yang ◽  
Je-Chin Han
Keyword(s):  
Film Cooling ◽  
Momentum Flux ◽  
Density Ratio ◽  
Flux Ratio ◽  
Suction Side ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Shaped Hole ◽  
Compound Angle

Adiabatic film-cooling effectiveness is examined systematically on a typical high pressure turbine blade by varying three critical flow parameters: coolant blowing ratio, coolant-to-mainstream density ratio, and freestream turbulence intensity. Three average coolant blowing ratios 1.0, 1.5, and 2.0; three coolant density ratios 1.0, 1.5, and 2.0; two turbulence intensities 4.2% and 10.5%, are chosen for this study. Conduction-free pressure sensitive paint (PSP) technique is used to measure film-cooling effectiveness. Three foreign gases — N2 for low density, CO2 for medium density, and a mixture of SF6 and Argon for high density are selected to study the effect of coolant density. The test blade features 45° compound-angle shaped holes on the suction side and pressure side, and 3 rows of 30° radial-angle cylindrical holes around the leading edge region. The inlet and the exit Mach number are 0.27 and 0.44, respectively. Reynolds number based on the exit velocity and blade axial chord length is 750,000. Results reveal that the PSP is a powerful technique capable of producing clear and detailed film effectiveness contours with diverse foreign gases. As blowing ratio exceeds the optimum value, it induces more mixing of coolant and mainstream. Thus film-cooling effectiveness reduces. Greater coolant-to-mainstream density ratio results in lower coolant-to-mainstream momentum and prevents coolant to lift-off; as a result, film-cooling increases. Higher freestream turbulence causes effectiveness to drop everywhere except in the region downstream of suction side. Results are also correlated with momentum flux ratio and compared with previous studies. It shows that compound shaped hole has the greatest optimum momentum flux ratio, and then followed by axial shaped hole, compound cylindrical hole, and axial cylindrical hole.

High Resolution Film Cooling Effectiveness Comparison of Axial and Compound Angle Holes on the Suction Side of a Turbine Vane

2006 ◽  
Author(s):  
Scot K. Waye ◽  
David G. Bogard
Keyword(s):  
High Resolution ◽  
Flat Plate ◽  
Film Cooling ◽  
Density Ratio ◽  
Suction Side ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Turbine Vane ◽  
Adiabatic Effectiveness ◽  
Compound Angle

Film cooling adiabatic effectiveness for axial and compound angle holes on the suction side of a simulated turbine vane was investigated to determine the relative performance of these configurations. The effect of the surface curvature was also evaluated by comparing to previous curvature studies and flat plate film cooling results. Experiments were conducted for varying coolant density ratio, mainstream turbulence levels, and hole spacing. Results from these measurements showed that for mild curvature, 2r/d ≈ 160, flat plate results are sufficient to predict the cooling effectiveness. Furthermore, the compound angle injection improves adiabatic effectiveness for higher blowing ratios, similar to previous studies using flat plate facilities.

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