Practical Slot Configurations for Turbine Film Cooling Applications

2009 ◽  
Author(s):  
Joshua E. Bruce-Black ◽  
Frederick T. Davidson ◽  
David G. Bogard ◽  
David R. Johns
Keyword(s):  
Film Cooling ◽  
Flow Characteristics ◽  
Suction Side ◽  
Operating Conditions ◽  
Coolant Flow ◽  
Film Cooling Effectiveness ◽  
Diffusion Technique ◽  
Turbine Vane ◽  
Structural Weakness ◽  
Turbine Component

Turbine component film cooling is most effective when using a continuous slot to introduce coolant to the surface. However, this is not practical due to the structural weakness that would be inherent with a continuous slot. In this study, several slot-like designs are investigated to establish the film cooling effectiveness. These slot configurations extended only a partial distance through the simulated turbine vane wall, and were fed with impinging cylindrical holes. The configurations were studied on the suction side of a scaled-up turbine vane. In this study varying slot widths, discrete and continuous slots, and diffusing the coolant flow within the slot prior to it being emitted onto the surface of the vane were investigated. Rows of discrete round and shaped holes were also tested for comparison with the slots. The study of varying slot geometries showed that decreasing the width of the slots led to a substantial increase in adiabatic effectiveness. An internal coolant diffusion technique showed promise by maintaining performance levels while potentially providing a design configuration that more readily meets structural demands in real world operating conditions. The coolant flow characteristics were also studied through the use of thermal profiles measurements. These thermal profiles showed significant mainstream ingestion on the top surface of the slot prior to the coolant emitting onto the surface of the vane.

Practical Slot Configurations for Turbine Film Cooling Applications

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
Joshua E. Bruce-Black ◽  
Frederick T. Davidson ◽  
David G. Bogard ◽  
David R. Johns
Keyword(s):  
Film Cooling ◽  
Flow Characteristics ◽  
Suction Side ◽  
Operating Conditions ◽  
Coolant Flow ◽  
Film Cooling Effectiveness ◽  
Diffusion Technique ◽  
Turbine Vane ◽  
Structural Weakness ◽  
Turbine Component

Turbine component film cooling is most effective when using a continuous slot to introduce coolant to the surface. However, this is not practical due to the structural weakness that would be inherent with a continuous slot. In this study, several slotlike designs are investigated to establish the film cooling effectiveness. These slot configurations extended only a partial distance through the simulated turbine vane wall and were fed with impinging cylindrical holes. The configurations were studied on the suction side of a scaled-up turbine vane. In this study, varying slot widths, discrete and continuous slots, and diffusing the coolant flow within the slot prior to it being emitted onto the surface of the vane were investigated. Rows of discrete round and shaped holes were also tested for comparison with the slots. The study of varying slot geometries showed that decreasing the width of the slots led to a substantial increase in adiabatic effectiveness. An internal coolant diffusion technique showed promise by maintaining performance levels while potentially providing a design configuration that more readily meets structural demands in real-world operating conditions. The coolant flow characteristics were also studied through the use of thermal profiles measurements. These thermal profiles showed minimal mainstream ingestion on the top surface of the slot prior to the coolant emitting onto the surface of the vane.

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.

Mean and Turbulent Velocity Profile Measurements on the Suction Side of a Film Cooled Turbine Vane

2013 ◽  
Author(s):  
John W. McClintic ◽  
Thomas E. Dyson ◽  
David G. Bogard ◽  
Sean D. Bradshaw
Keyword(s):  
Boundary Layer ◽  
Velocity Profile ◽  
Film Cooling ◽  
Large Scale ◽  
Suction Side ◽  
Profile Data ◽  
Downstream Location ◽  
Film Cooling Effectiveness ◽  
Turbine Vane ◽  
Layer Velocity

Boundary layer velocity and turbulence profiles were measured on the suction side of a scaled up, film-cooled turbine vane airfoil. There have been a number of previous studies of the velocity profile on a turbine vane, but few have taken velocity profile data with film cooling, and none have taken such data on the suction side of the vane. Velocity and turbulence profile data were taken at two locations on the suction side of the vane — one at a high curvature region and one further downstream in a low curvature region. Data were collected for high (20%) and low (0.5%) mainstream turbulence conditions. For the upstream, high curvature location, velocity and turbulence profiles were found with and without the showerhead blowing and within and outside of the merged showerhead coolant jet. The data for the low curvature, downstream location was taken with injection from the showerhead alone, a second upstream row of holes alone, and the combination of the two cases. It was found that the presence of an active upstream row of holes thickens the boundary layer and increases urms both within and beyond the extent of the boundary layer. Span-wise variations showed that these effects are strongest within the core of the coolant jets. At the downstream location, the boundary layer velocity profile was most strongly influenced by the row of holes immediately upstream of that location. Finally, turbulence integral length scale data showed the effect of large scale mainstream turbulence penetrating the boundary layer. The increase in turbulence, thickening of the boundary layer, and large scale turbulence all play important roles in row to row coolant interactions and affect the film cooling effectiveness.

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.

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.

Influence of Shock Wave on Turbine Vane Suction Side Film Cooling With Compound-Angle Shaped Holes

2011 ◽  
Author(s):  
K. Liu ◽  
D. P. Narzary ◽  
J. C. Han ◽  
A. V. Mirzamoghadam ◽  
A. Riahi
Keyword(s):  
Transonic Flow ◽  
Film Cooling ◽  
Flux Ratio ◽  
Suction Side ◽  
Flow Conditions ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Turbine Vane ◽  
Compound Angle

This paper studies the effect of shock wave on turbine vane suction side film cooling using a conduction-free Pressure Sensitive Paint (PSP) technique. Tests were performed in a five-vane annular cascade with a blow-down flow loop facility. The exit Mach numbers are controlled to be 0.7, 1.1, and 1.3, from subsonic to transonic flow conditions. Two foreign gases N2 and CO2 are selected to study the effects of two coolant-to-mainstream density ratios, 1.0 and 1.5, on film cooling. Four averaged coolant blowing ratios in the range, 0.4 to 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 is an accurate technique capable of producing clear and detailed film cooling effectiveness contours at transonic flow conditions. At lower blowing ratio, film cooling effectiveness decreases with increasing exit Mach number. On the other hand, an opposite trend is observed at high blowing ratio. In transonic flow, the rapid rise in pressure caused by shock benefits film-cooling by deflecting the coolant jet toward the vane surface at higher blowing ratio. Results show that denser coolant performs better, typically at higher blowing ratio in transonic flow. Results also show that the optimum momentum flux ratio decreases with density ratio at subsonic condition. In transonic flow, however, the trend is reversed and the peak effectiveness values plateau over a long range of momentum flux ratio.

Experimental Investigations of the Film Cooling Performance of a Micro-Tangential-Jet Scheme on a Gas Turbine Vane: Part 1 — Effectiveness

2012 ◽  
Author(s):  
O. Hassan ◽  
I. Hassan
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Density Ratio ◽  
Suction Side ◽  
Experimental Investigations ◽  
Stream Velocity ◽  
Pressure Side ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Turbine Vane

This paper presents experimental investigations of the film cooling effectiveness performance of a Micro-Tangential-Jet (MTJ) Film cooling scheme on a gas turbine vane using transient Thermochromic Liquid Crystal (TLC) technique. The MTJ scheme is a micro-shaped scheme designed so that the secondary jet is supplied tangentially to the vane surface. The scheme combines the benefits of micro jets and tangential injection. The film cooling performance of one row of holes on both pressure and suction sides were investigated at a blowing ratio ranging from 0.5 to 1.5 on the pressure side and 0.25 to 0.625 on the suction side. The average density ratio during the investigations was 0.93, and the Reynolds Number was 1.4E+5, based on the free stream velocity and the main duct hydraulic diameter. The pitch to diameter ratio of the cooling holes is 5 on the pressure side and 6.5 on the suction side. The turbulence intensity during all investigations was 8.5%. Minor changes in the Mach number distribution around the airfoil surface were observed due to the presence of the MTJ scheme, compared with the case with no MTJ scheme. The investigations showed great film cooling performance for the MTJ scheme, high effectiveness values, and excellent lateral jet spreading. A 2-D coolant film was observed in the results, which is a characteristic of the continuous slot schemes only. The presence of this 2-D film layer helps minimize the rate of mixing between the main and coolant streams and provides uniform thermal loads on the surface. Furthermore, it was noticed that the rate of effectiveness decay on the suction side was less than that on the pressure side, while the lateral jet spreading on the pressure side was better than that of the suction side. The main disadvantage of the MTJ scheme is the increased pressure drop.

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

2006 ◽  
Vol 129 (2) ◽  
pp. 202-211 ◽  
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.

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

2007 ◽  
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 imbedded in a shallow trench significantly improve cooling performance. In this study, the performance of shallow trench configurations were 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.

Multi-Row Film Cooling Performances of a High Lift Blade and Vane

2012 ◽  
Author(s):  
S. Naik ◽  
J. Krueckels ◽  
M. Gritsch ◽  
M. Schnieder
Keyword(s):  
Film Cooling ◽  
Guide Vane ◽  
Suction Side ◽  
Operating Conditions ◽  
Pressure Side ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
High Lift ◽  
Film Cooling Effectiveness ◽  
Film Cooling Holes

This paper investigates the aerodynamic and film cooling effectiveness characteristics of a first stage turbine high lift guide vane and its corresponding downstream blade. The vane and blade geometrical profiles and operating conditions are representative of that normally found in a heavy-duty gas turbine. Both the vane and the blade airfoils consist of multi-row film cooling holes located at various axial positions along the airfoil chord. The film cooling holes are geometrically three-dimensional in shape and depending on the location on the airfoil; they can be either symmetrically fan shaped or non-symmetrically fan shaped. Additionally the film cooling holes can be either compounded or in-line with the external flow direction. Numerical studies and experimental investigations in a linear cascade have been conducted at vane and blade exit isentropic Mach number of 0.8. The influence of the coolant flow ejected from the film cooling holes has been investigated for both the vane and the blade profiles. For the nozzle guide vane, the measured film cooling effectiveness compared well with the predictions, especially on the pressure side. The suction side film cooling effectiveness, which consisted of two pre-throat film rows, proved very effective up-to the suction side trailing edge. For the blade, there was a reasonable comparison between the measured and predicted film cooling effectiveness. Again the blade pre-throat fan shaped cooling holes proved very effective up-to the suction side trailing edge. For the vane, the impact of varying the blowing ratios showed a strong variation in the film cooling effectiveness on the pressure side. However, on the blade, the effect of varying the blowing ratio had a greater impact on the suction side film effectiveness compared to the pressure side.

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