A Parametric Investigation of Vane Showerhead Film Cooling by PSP Technique

2019 ◽  
Author(s):  
H. Abdeh ◽  
G. Barigozzi ◽  
S. Ravelli ◽  
S. Rouina
Keyword(s):  
Turbulence Intensity ◽  
Film Cooling ◽  
Cooling System ◽  
Density Ratio ◽  
Leading Edge ◽  
Intensity Level ◽  
Cooling Performance ◽  
Blowing Ratio ◽  
Cylindrical Holes ◽  
Exit Mach Number

Abstract In this study a parametric analysis of the thermal performance of a nozzle vane cascade with a showerhead cooling system made of four rows of cylindrical holes was carried out by using the Pressure Sensitive Paint (PSP) technique. Coolant-to-mainstream blowing ratio (BR), density ratio (DR), main flow isentropic exit Mach number (Ma2is) and turbulence intensity level (Tu1) were the considered parameters. The cascade was tested in an atmospheric wind tunnel at Ma2is values ranging from 0.2 to 0.6, with an inlet turbulence intensity level of 1.6% and 9%, at variable injection conditions of BR = 2.0, 3.0, 4.0. Moreover, the influence of DR on the leading edge film cooling performance was investigated: testing was carried out at DR = 1.0, using nitrogen as foreign gas, and DR = 1.5, with carbon dioxide serving as coolant. In the near-hole region, higher BR and Ma2is resulted in higher effectiveness, while higher mainstream turbulence intensity reduced the thermal coverage in between the rows of holes, whatever the BR. Further downstream along the vane pressure side, the effectiveness was negatively affected by rising BR, but positively influenced by lowering the mainstream turbulence intensity. Moreover, a decrease in DR caused a reduction in the film cooling performance, whose extent depends on the injection condition.

A Parametric Investigation of Vane Showerhead Film Cooling by Pressure-Sensitive Paint Technique

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
H. Abdeh ◽  
G. Barigozzi ◽  
S. Ravelli ◽  
S. Rouina
Keyword(s):  
Turbulence Intensity ◽  
Film Cooling ◽  
Cooling System ◽  
Density Ratio ◽  
Leading Edge ◽  
Intensity Level ◽  
Pressure Sensitive Paint ◽  
Cooling Performance ◽  
Pressure Sensitive ◽  
Exit Mach Number

Abstract In this study, a parametric analysis of the thermal performance of a nozzle vane cascade with a showerhead cooling system made of four rows of cylindrical holes was carried out by using the pressure-sensitive paint (PSP) technique. Coolant-to-mainstream blowing ratio (BR), density ratio (DR), main flow isentropic exit Mach number (Ma2is), and turbulence intensity level (Tu1) were the considered parameters. The cascade was tested in an atmospheric wind tunnel at Ma2is values ranging from 0.2 to 0.6, with an inlet turbulence intensity level of 1.6% and 9%, at variable injection conditions of BR = 2.0, 3.0, 4.0. Moreover, the influence of the DR on the leading-edge film-cooling performance was investigated: the testing was carried out at DR = 1.0, using nitrogen as foreign gas, and DR = 1.5, with carbon dioxide serving as a coolant. In the near-hole region, higher BR and Ma2is resulted in higher effectiveness, while higher mainstream turbulence intensity reduced the thermal coverage in between the rows of holes, whatever the BR is. Further downstream along the vane pressure side, the effectiveness was negatively affected by rising the BR but positively influenced by lowering the mainstream turbulence intensity. Moreover, a decrease in the DR caused a reduction in the film-cooling performance, whose extent depends on the injection condition.

Influence of Coolant Density on Turbine Platform Film-Cooling With Stator–Rotor Purge Flow and Compound-Angle Holes

2014 ◽  
Vol 6 (4) ◽  
Author(s):  
Kevin Liu ◽  
Shang-Feng Yang ◽  
Je-Chin Han
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Fundamental Parameters ◽  
Blowing Ratio ◽  
Purge Flow ◽  
Cylindrical Holes ◽  
Exit Mach Number ◽  
Compound Angle

A detailed parametric study of film-cooling effectiveness was carried out on a turbine blade platform. The platform was cooled by purge flow from a simulated stator–rotor seal combined with discrete hole film-cooling. The cylindrical holes and laidback fan-shaped holes were accessed in terms of film-cooling effectiveness. This paper focuses on the effect of coolant-to-mainstream density ratio on platform film-cooling (DR = 1 to 2). Other fundamental parameters were also examined in this study—a fixed purge flow of 0.5%, three discrete-hole film-cooling blowing ratios between 1.0 and 2.0, and two freestream turbulence intensities of 4.2% and 10.5%. Experiments were done in a five-blade linear cascade with inlet and exit Mach number of 0.27 and 0.44, respectively. Reynolds number of the mainstream flow was 750,000 and was based on the exit velocity and chord length of the blade. The measurement technique adopted was the conduction-free pressure sensitive paint (PSP) technique. Results indicated that with the same density ratio, shaped holes present higher film-cooling effectiveness and wider film coverage than the cylindrical holes, particularly at higher blowing ratios. The optimum blowing ratio of 1.5 exists for the cylindrical holes, whereas the effectiveness for the shaped holes increases with an increase of blowing ratio. Results also indicate that the platform film-cooling effectiveness increases with density ratio but decreases with turbulence intensity.

Experimental Study of the Effects of an Oscillating Approach Flow on Overall Cooling Performance of a Simulated Turbine Blade Leading Edge

2009 ◽  
Author(s):  
Ross Johnson ◽  
Jonathan Maikell ◽  
David Bogard ◽  
Justin Piggush ◽  
Atul Kohli ◽  
...  
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Density Ratio ◽  
Leading Edge ◽  
Stagnation Line ◽  
Cooling Performance ◽  
Blowing Ratio ◽  
Oscillation Frequencies ◽  
Overall Effectiveness ◽  
Blade Leading Edge

When a turbine blade passes through wakes from upstream vanes it is subjected to an oscillation of the direction of the approach flow resulting in the oscillation of the position of the stagnation line on the leading edge of the blade. In this study an experimental facility was developed that induced a similar oscillation of the stagnation line position on a simulated turbine blade leading edge. The overall effectiveness was evaluated at various blowing ratios and stagnation line oscillation frequencies. The location of the stagnation line on the leading edge was oscillated to simulate a change in angle of attack between α = ± 5° at a range of frequencies from 2 to 20 Hz. These frequencies were chosen based on matching a range of Strouhal numbers typically seen in an engine due to oscillations caused by passing wakes. The blowing ratio was varied between M = 1, M = 2, and M = 3. These experiments were carried out at a density ratio of DR = 1.5 and mainstream turbulence levels of Tu ≈ 6%. The leading edge model was made of high conductivity epoxy in order to match the Biot number of an actual engine airfoil. Results of these tests showed that the film cooling performance with an oscillating stagnation line was degraded by as much as 25% compared to the performance of a steady flow with the stagnation line aligned with the row of holes at the leading edge.

Effect of Coolant Density on Leading Edge Showerhead Film Cooling Using PSP Measurement Technique

2013 ◽  
Author(s):  
Shiou-Jiuan Li ◽  
Shang-Feng Yang ◽  
Je-Chin Han
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Leading Edge ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Pressure Sensitive ◽  
Cylindrical Holes ◽  
Film Cooling Holes ◽  
Compound Angle ◽  
Low Speed Wind Tunnel

The density ratio effect on leading edge showerhead film cooling has been studied experimentally using the pressure sensitive paint (PSP) mass transfer analogy method. Leading edge model is a blunt body with a semi-cylinder and an after body. There are two designs: seven-row and three-row of film cooling holes for simulating vane and blade, respectively. The film holes are located at 0 (stagnation row), ±15, ±30, and ±45 deg for seven-row design, and at 0 and ±30 for three-row design. Four film holes configurations are used for both test designs: radial angle cylindrical holes, compound angle cylindrical holes, radial angle shaped holes, and compound angle shaped holes. Coolant to mainstream density ratio varies from DR = 1.0, 1.5, to 2.0 while blowing ratio varies from M = 0.5 to 2.1. Experiments were conducted in a low speed wind tunnel with Reynolds number 100,900 based on mainstream velocity and diameter of the cylinder. The mainstream turbulence intensity near leading edge model is about 7%. The results show the shaped holes have overall higher film cooling effectiveness than cylindrical holes, and radial angle holes are better than compound angle holes, particularly at higher blowing ratio. Larger density ratio makes more coolant attach to the surface and increases film protection for all cases. Radial angle shaped holes provides best film cooling at higher density ratio and blowing ratio for both designs.

Enhancement of Film Cooling Performance at the Leading Edge of Turbine Blade

2006 ◽  
Author(s):  
K.-S. Kim ◽  
Youn J. Kim ◽  
S.-M. Kim
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Density Ratio ◽  
Leading Edge ◽  
Cylindrical Body ◽  
Spanwise Direction ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio

To enhance the film cooling performance in the vicinity of the turbine blade leading edge, the flow characteristics of the film-cooled turbine blade have been investigated using a cylindrical body model. The inclination of the cooling holes is along the radius of the cylindrical wall and 20 deg relative to the spanwise direction. Mainstream Reynolds number based on the cylinder diameter was 1.01×105 and 0.69×105, and the mainstream turbulence intensities were about 0.2% in both Reynolds numbers. CO2 was used as coolant to simulate the effect of density ratio of coolant-to-mainstream. Furthermore, the effect of coolant flow rates was studied for various blowing ratios of 0.4, 0.7, 1.1, and 1.4, respectively. In experiment, spatially-resolved temperature distributions along the cylindrical body surface were visualized using infrared thermography (IRT) in conjunction with thermocouples, digital image processing, and in situ calibration procedures. This comparison shows the results generated to be reasonable and physically meaningful. The film cooling effectiveness of current measurement (0.29 mm × 0.33 min per pixel) presents high spatial and temperature resolutions compared to other studies. Results show that the blowing ratio has a strong effect on film cooling effectiveness and the coolant trajectory is sensitive to the blowing ratio. The local spanwise-averaged effectiveness can be improved by locating the first-row holes near the second-row holes.

Effect of Density Ratio on Flat Plate Film Cooling With Shaped Holes Using PSP

2010 ◽  
Author(s):  
Lesley M. Wright ◽  
Stephen T. McClain ◽  
Michael D. Clemenson
Keyword(s):  
Flat Plate ◽  
Turbulence Intensity ◽  
Film Cooling ◽  
Density Ratio ◽  
Freestream Turbulence ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Cylindrical Holes ◽  
Film Cooling Holes

Detailed film cooling effectiveness distributions are obtained on a flat plate using the pressure sensitive paint (PSP) technique. The applicability of the PSP technique is expanded to include a coolant-to-mainstream density ratio of 1.4. The effect of density ratio on the film cooling effectiveness is coupled with varying blowing ratio (M = 0.25–2.0), freestream turbulence intensity (Tu = 1%–12.5%), and film hole geometry. The effectiveness distributions are obtained on three separate flat plates containing either simple angle, cylindrical holes, simple angle, fanshaped holes (α = 10°), or simple angle, laidback, fanshaped holes (α = 10°, γ = 10°). In all three cases, the film cooling holes are angled at θ = 35° from the mainstream flow. Using the PSP technique, the combined effects of blowing ratio, turbulence intensity, and density ratio are captured for each film cooling geometry. The detailed film cooling effectiveness distributions, for cylindrical holes, clearly show the effectiveness at the lowest blowing ratio is enhanced at the lower density ratio (DR = 1). However, as the blowing ratio increases, a transition occurs, leading to increased effectiveness with the elevated density ratio (DR = 1.4). In addition, the PSP technique captures an upstream shift of the coolant jet reattachment point as the density ratio increases or the turbulence intensity increases (at moderate blowing ratios for cylindrical holes). With the decreased momentum of the shaped film cooling holes, the greatest film cooling effectiveness is obtained at the lower density ratio (DR = 1.0) over the entire range of blowing ratios considered. In all cases, as the freestream turbulence intensity increases, the film effectiveness decreases; this effect is reduced as the blowing ratio increases for all three film hole configurations.

Effect of Coolant Density on Leading Edge Showerhead Film Cooling Using the Pressure Sensitive Paint Measurement Technique

2013 ◽  
Vol 136 (5) ◽  
Author(s):  
Shiou-Jiuan Li ◽  
Shang-Feng Yang ◽  
Je-Chin Han
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Leading Edge ◽  
Pressure Sensitive Paint ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Pressure Sensitive ◽  
Cylindrical Holes ◽  
Film Cooling Holes ◽  
Compound Angle

The density ratio effect on leading edge showerhead film cooling has been studied experimentally using the pressure sensitive paint (PSP) mass transfer analogy method. The leading edge model is a blunt body with a semicylinder and an after body. There are two designs: seven-row and three-row of film cooling holes for simulating a vane and blade, respectively. The film holes are located at 0 (stagnation row), ±15, ±30, and ±45 deg for the seven-row design, and at 0 and ±30 for the three-row design. Four film hole configurations are used for both test designs: radial angle cylindrical holes, compound angle cylindrical holes, radial angle shaped holes, and compound angle shaped holes. The coolant to mainstream density ratio varies from DR = 1.0, 1.5, to 2.0 while the blowing ratio varies from M = 0.5 to 2.1. Experiments were conducted in a low speed wind tunnel with Reynolds number 100,900 based on mainstream velocity and diameter of the cylinder. The mainstream turbulence intensity near the leading edge model is about 7%. The results show the shaped holes have an overall higher film cooling effectiveness than the cylindrical holes, and the radial angle holes are better than the compound angle holes, particularly at a higher blowing ratio. A larger density ratio makes more coolant attach to the surface and increases film protection for all cases. Radial angle shaped holes provide the best film cooling at a higher density ratio and blowing ratio for both designs.

Effect of Density Ratio on Flat Plate Film Cooling With Shaped Holes Using PSP

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Lesley M. Wright ◽  
Stephen T. McClain ◽  
Michael D. Clemenson
Keyword(s):  
Flat Plate ◽  
Turbulence Intensity ◽  
Film Cooling ◽  
Density Ratio ◽  
Freestream Turbulence ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Cylindrical Holes ◽  
Film Cooling Holes

Detailed film-cooling effectiveness distributions are obtained on a flat plate using the pressure sensitive paint (PSP) technique. The applicability of the PSP technique is expanded to include a coolant-to-mainstream density ratio of 1.4. The effect of density ratio on the film-cooling effectiveness is coupled with varying blowing ratio (M=0.25–2.0), freestream turbulence intensity (Tu=1–12.5%), and film hole geometry. The effectiveness distributions are obtained on three separate flat plates containing either simple angle, cylindrical holes, simple angle, fanshaped holes (α=10 deg), or simple angle, laidback, fanshaped holes (α=10 deg and γ=10 deg). In all three cases, the film-cooling holes are angled at θ=35 deg from the mainstream flow. Using the PSP technique, the combined effects of blowing ratio, turbulence intensity, and density ratio are captured for each film-cooling geometry. The detailed film-cooling effectiveness distributions, for cylindrical holes, clearly show that the effectiveness at the lowest blowing ratio is enhanced at the lower density ratio (DR=1). However, as the blowing ratio increases, a transition occurs, leading to increased effectiveness with the elevated density ratio (DR=1.4). In addition, the PSP technique captures an upstream shift of the coolant jet reattachment point as the density ratio increases or the turbulence intensity increases (at moderate blowing ratios for cylindrical holes). With the decreased momentum of the shaped film-cooling holes, the greatest film-cooling effectiveness is obtained at the lower density ratio (DR=1.0) over the entire range of blowing ratios considered. In all cases, as the freestream turbulence intensity increases, the film effectiveness decreases; this effect is reduced as the blowing ratio increases for all three film hole configurations.

Experimental Investigation of Net Heat Flux Reduction at Combustion Temperatures

2015 ◽  
Author(s):  
Nathan J. Greiner ◽  
Marc D. Polanka ◽  
James L. Rutledge ◽  
Andrew T. Shewhart
Keyword(s):  
Heat Flux ◽  
Experimental Investigation ◽  
Film Cooling ◽  
Density Ratio ◽  
Plate Surface ◽  
Cooling Performance ◽  
Single Row ◽  
Blowing Ratio ◽  
Net Heat Flux ◽  
Cylindrical Holes

The present work examines film cooling on a flat plate surface with a freestream temperature between 1430K and 1600K and a coolant to freestream density ratio of approximately two. Since the objective of film cooling is to reduce heat flux to a surface, Net Heat Flux Reduction (NHFR) is used to quantify film cooling performance. It is first demonstrated that non-dimensional matching can be used to scale NHFR between freestream temperature conditions of 1490K and 1600K. Next, the NHFR of a single row of cylindrical holes, fan-shaped holes, holes embedded in a trench, and a slot are compared at a blowing ratio of unity. Finally, the NHFR of five rows of cylindrical holes, holes embedded in trenches, and slots are compared to show the effect of a build-up of coolant near the wall.

Experimental Study on the Film Cooling Performance at the Leading Edge of Turbine Blade Using Infrared Thermography

2006 ◽  
Vol 326-328 ◽  
pp. 1161-1164
Author(s):  
Kwang Su Kim ◽  
Youn Jea Kim
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Turbine Blades ◽  
Density Ratio ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Cylindrical Body ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio

In order to protect turbine blades from high temperature, film cooling can be applied to gas turbine engine system since it can prevent corrosion and facture of material. To enhance the film cooling performance in the vicinity of the turbine blade leading edge, flow characteristics of the film-cooled turbine blade have been investigated using a cylindrical body model. Mainstream Reynolds number based on the cylinder diameter was 1.01×105 and the mainstream turbulence intensities were about 0.2%. CO2 was used as coolant to simulate the effect of coolant-tomainstream density ratio. The effect of coolant flow rates was studied for various blowing ratios of 0.5, 0.8, 1.1 and 1.4, respectively. Results show that the blowing ratio has a strong effect on film cooling effectiveness and the coolant trajectory is sensitive to the blowing ratio.

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