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.

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.

scholarly journals Flat Plate and Turbine Vane Film-Cooling Performance with Laid-Back Fan-Shaped Holes

2019 ◽  
Vol 4 (2) ◽  
pp. 14 ◽  
Author(s):  
Tommaso Bacci ◽  
Alessio Picchi ◽  
Bruno Facchini
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Density Ratio ◽  
Pressure Sensitive Paint ◽  
Cooling Performance ◽  
Blowing Ratio ◽  
Pressure Sensitive ◽  
Turbine Vane ◽  
Experimental Works ◽  
Lift Off

Shaped holes are considered as an effective solution to enhance gas turbine film-cooling performance, as they allow to increase the coolant mass-flux, while limiting the detrimental lift-off phenomena. A great amount of work has been carried out in past years on basic flat plate configurations while a reduced number of experimental works deals with a quantitative assessment of the influence of curvature and vane pressure gradient. In the present work PSP (Pressure Sensitive Paint) technique is used to detail the adiabatic effectiveness generated by axial shaped holes with high value of Area Ratio close to 7, in three different configurations with the same 1:1 scale: first of all, a flat plate configuration is examined; after that, the film-cooled pressure and suction sides of a turbine vane model are investigated. Tests were performed varying the blowing ratio and imposing a density ratio of 2.5 . The experimental results are finally compared to the predictions of two different correlations, developed for flat plate 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.

Upstream Film Cooling on the Contoured Endwall of a Transonic Turbine Vane in an Annular Cascade

2020 ◽  
Author(s):  
Daniel A. Salinas ◽  
Izhar Ullah ◽  
Lesley M. Wright ◽  
Je-Chin Han ◽  
John W. McClintic ◽  
...  
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Lateral Spread ◽  
Pressure Sensitive Paint ◽  
Blow Down ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive ◽  
Mainstream Flow ◽  
Additional Protection ◽  
Annular Cascade

Abstract The effects of mainstream flow velocity, density ratio (DR), and coolant-to-mainstream mass flow ratio (MFR) were investigated on a vane endwall in a transonic, annular cascade. A blow down facility consisting of five vanes was used. The film cooling effectiveness was measured using binary pressure sensitive paint (BPSP). The mainstream flow was set using isentropic exit Mach numbers of 0.7 and 0.9. The coolant-to-mainstream density ratio varied from 1.0 to 2.0. The coolant to mainstream MFR varied from 0.75% to 1.25%. The endwall was cooled by eighteen discrete holes located upstream of the vane passage to provide cooling to the upstream half of the endwall. Due to the curvature of the vane endwall, the upstream holes provided uniform coverage entering the endwall passage. The coverage was effective leading to the throat of the passage, where the downstream holes could provide additional protection. Increasing the coolant flowrate increased the effectiveness provided by the film cooling holes. Increasing the density of the coolant increases the effectiveness on the endwall while enhancing the lateral spread of the coolant. Finally, increasing the velocity of the mainstream while holding the MFR constant also yields increased protection on the endwall. Over the range of flow conditions considered in this study, the binary pressure sensitive paint proved to be a valuable tool for obtaining detailed pressure and film effectiveness distributions.

Endwall Heat Transfer and Cooling Performance of a Transonic Turbine Vane with Upstream Injection Flow

2021 ◽  
pp. 1-24
Author(s):  
Zhigang LI ◽  
Bo Bai ◽  
Jun Li ◽  
Shuo Mao ◽  
Wing Ng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Density Ratio ◽  
Gas Temperature ◽  
Blow Down ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Injection Flow ◽  
Coolant Injection ◽  
Exit Mach Number

Abstract Detailed experimental and numerical studies on endwall heat transfer and cooling performance with coolant injection flow through upstream discrete holes is presented in this paper. High resolution heat transfer coefficient (HTC) and adiabatic film cooling effectiveness values were measured using a transient infrared thermography technique on an axisymmetric contoured endwall. The tests were performed in a transonic linear cascade blow-down wind tunnel facility. Conditions were representative of a land-based power generation turbine with exit Mach number of 0.85 corresponding to exit Reynolds number of 1.5 × 106, based on exit condition and axial chord length. A high turbulence level of 16% with an integral length scale of 3.6%P was generated using inlet turbulence grid to reproduce the typical turbulence conditions in real turbine. Low temperature air was used to simulate the typical coolant-to-mainstream condition by controlling two parameters of the upstream coolant injection flow: mass flow rate to determine the coolant-to-mainstream blowing ratio (BR = 2.5, 3.5), and gas temperature to determine the density ratio (DR = 1.2). To highlight the interactions between the upstream coolant flow and the passage secondary flow combined with the influence on the endwall heat transfer and cooling performance, a comparison of CFD predictions to experimental results was performed by solving steady-state Reynolds-Averaged Navier-Stokes (RANS) using the commercial CFD solver ANSYS Fluent V.15.

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.

Influence of Coolant Density on Turbine Blade Film Cooling at Transonic Cascade Flow Conditions Using the Pressure Sensitive Paint Technique

2021 ◽  
Author(s):  
Izhar Ullah ◽  
Sulaiman M. Alsaleem ◽  
Lesley M. Wright ◽  
Chao-Cheng Shiau ◽  
Je-Chin Han
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Pressure Side ◽  
Pressure Sensitive Paint ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Pressure Sensitive ◽  
Blade Tip ◽  
Film Cooling Holes

Abstract This work is an experimental study of film cooling effectiveness on a blade tip in a stationary, linear cascade. The cascade is mounted in a blowdown facility with controlled inlet and exit Mach numbers of 0.29 and 0.75, respectively. The free stream turbulence intensity is measured to be 13.5 % upstream of the blade’s leading edge. A flat tip design is studied, having a tip gap of 1.6%. The blade tip is designed to have 15 shaped film cooling holes along the near-tip pressure side (PS) surface. Fifteen vertical film cooling holes are placed on the tip near the pressure side. The cooling holes are divided into a 2-zone plenum to locally maintain the desired blowing ratios based on the external pressure field. Two coolant injection scenarios are considered by injecting coolant through the tip holes only and both tip and PS surface holes together. The blowing ratio (M) and density ratio (DR) effects are studied by testing at blowing ratios of 0.5, 1.0, and 1.5 and three density ratios of 1.0, 1.5, and 2.0. Three different foreign gases are used to create density ratio effect. Over-tip flow leakage is also studied by measuring the static pressure distributions on the blade tip using the pressure sensitive paint (PSP) measurement technique. In addition, detailed film cooling effectiveness is acquired to quantify the parametric effect of blowing ratio and density ratio on a plane tip design. Increasing the blowing ratio and density ratio resulted in increased film cooling effectiveness at all injection scenarios. Injecting coolant on the PS and the tip surface also resulted in reduced leakage over the tip. The conclusions from this study will provide the gas turbine designer with additional insight on controlling different parameters and strategically placing the holes during the design process.

Platform Film Cooling Investigation on an HP Nozzle Vane Cascade With Discrete Shaped Holes and Slot Film Cooling

2020 ◽  
Author(s):  
G. Barigozzi ◽  
A. Perdichizzi ◽  
L. Abba ◽  
L. Pestelli
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Heat Transfer Performance ◽  
Leading Edge ◽  
Suction Side ◽  
Secondary Flows ◽  
Intensity Level ◽  
Transfer Performance ◽  
Film Cooling Effectiveness ◽  
Exit Mach Number

Abstract The present paper reports on an experimental investigation on the aerodynamic and heat transfer performance of different platform cooling schemes: two based on cylindrical and shaped holes and one featuring a slot located upstream of the leading edge plane simulating the combustor to stator interface gap. Tests were run on a 6-vane cascade operated at an isentropic cascade exit Mach number of 0.4 and a significant inlet turbulence intensity level of about 9%. The cooling schemes were first tested to quantify their impact on secondary flows and related losses for variable injection conditions. Heat transfer performance was then assessed through adiabatic film cooling effectiveness and heat transfer coefficient measurements. The Net Heat Flux Reduction parameter was then computed to critically assess the cooling schemes. When compared with the cylindrical hole scheme, shaped holes outperform for all tested injection rates, while the slot alone is able to thermally protect only the front of the passage. Discrete holes are required to cool the platform region along the whole pressure side and the suction side leading edge region.

Film Cooling Effectiveness on the Leading Edge Region of a Rotating Turbine Blade With Two Rows of Film Cooling Holes Using Pressure Sensitive Paint

2006 ◽  
Vol 128 (9) ◽  
pp. 879-888 ◽  
Author(s):  
Jaeyong Ahn ◽  
M. T. Schobeiri ◽  
Je-Chin Han ◽  
Hee-Koo Moon
Keyword(s):  
Rotational Speed ◽  
Film Cooling ◽  
Rotor Blade ◽  
Incidence Angle ◽  
Leading Edge ◽  
Edge Region ◽  
Pressure Sensitive Paint ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive

Detailed film cooling effectiveness distributions are measured on the leading edge of a rotating gas turbine blade with two rows (pressure-side row and suction-side row from the stagnation line) of holes aligned to the radial axis using the pressure sensitive paint (PSP) technique. Film cooling effectiveness distributions are obtained by comparing the difference of the measured oxygen concentration distributions with air and nitrogen as film cooling gas respectively and by applying the mass transfer analogy. Measurements are conducted on the first-stage rotor blade of a three-stage axial turbine at 2400rpm (positive off-design), 2550rpm (design), and 3000rpm (negative off-design), respectively. The effect of three blowing ratios is also studied. The blade Reynolds number based on the axial chord length and the exit velocity is 200,000 and the total to exit pressure ratio was 1.12 for the first-stage rotor blade. The corresponding rotor blade inlet and outlet Mach numbers are 0.1 and 0.3, respectively. The film cooling effectiveness distributions are presented along with discussions on the influence of rotational speed (off design incidence angle), blowing ratio, and upstream nozzle wakes around the leading edge region. Results show that rotation has a significant impact on the leading edge film cooling distributions with the average film cooling effectiveness in the leading edge region decreasing with an increase in the rotational speed (negative incidence angle).

Experimental Study of Effusion Cooling With Pressure-Sensitive Paint

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Guanghua Wang ◽  
Gustavo Ledezma ◽  
James DeLancey ◽  
Anquan Wang
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Cfd Simulation ◽  
Density Ratio ◽  
Open Loop ◽  
Pressure Sensitive Paint ◽  
Gas Temperature ◽  
Eddy Simulation ◽  
Pressure Sensitive ◽  
The Impact

Gas turbines overall efficiency enhancement requires further increasing of the firing temperature and decreasing of cooling flow usage. Multihole (or effusion, or full-coverage) film cooling is widely used for hot gas path components cooling in modern gas turbines. The present study focused on the adiabatic film effectiveness measurement of a round multihole flat-plate coupon. The measurements were conducted in a subsonic open-loop wind tunnel with a generic setup to cover different running conditions. The test conditions were characterized by a constant main flow Mach number of 0.1 with constant gas temperature. Adiabatic film effectiveness was measured by pressure-sensitive paint (PSP) through mass transfer analogy. CO2 was used as the coolant to reach the density ratio of 1.5. Rig computational fluid dynamics (CFD) simulation was conducted to evaluate the impact of inlet boundary layer on testing. Experimental data cover blowing ratios (BRs) at 0.4, 0.6, 0.8, 1.0, and 2.0. Both 2D maps and lateral average profiles clearly indicated that the film effectiveness increases with increasing BR for BR < 0.8 and decreases with increasing BR for BR > 0.8. This observation agreed with coolant jet behavior of single film row, i.e., attached, detached then reattached, and fully detached. PSP data quality was then discussed in detail for validating large eddy simulation.

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