FILM COOLING EFFECTIVENESS MEASUREMENT OF FAN-SHAPED HOLES MANUFACTURED USING EDM TECHNIQUE

2021 ◽  
pp. 1-16
Author(s):  
Samaneh Rouina ◽  
Hamed Abdeh ◽  
Giovanna Barigozzi ◽  
Vittorio Odemondo ◽  
Luca Abba ◽  
...  
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Injection Angle ◽  
Blowing Ratio ◽  
Pressure Sensitive ◽  
Geometric Factors ◽  
Expansion Angle ◽  
Effectiveness Measurement

Abstract In this study, the influence of geometric factors such as hole diameter (D), length-to-diameter ratio (L/D), injection angle (a), and lateral expansion angle (α) on film cooling effectiveness of holes made using EDM is experimentally investigated. Nine different cooling configurations were tested on a flat plate wind tunnel at various coolant Reynolds number (Rec) and coolant to mainstream blowing ratio (M). The considered flat plate model incorporates engine sized V-shaped holes. EDM reliability is assessed through a hole qualification process, while effectiveness was measured by the Pressure Sensitive Paint (PSP) technique. Results confirm the suitability of EDM for V-shaped hole manufacturing as long as a correct tolerance on α is prescribed. An accurate qualification of hole morphology is also recommended.

Film Cooling Effectiveness Measurement of Fan-Shaped Holes Manufactured Using EDM Technique

2021 ◽  
Author(s):  
S. Rouina ◽  
H. Abdeh ◽  
G. Barigozzi ◽  
V. Odemondo ◽  
L. Abba ◽  
...  
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Injection Angle ◽  
Blowing Ratio ◽  
Pressure Sensitive ◽  
Geometric Factors ◽  
Expansion Angle ◽  
Effectiveness Measurement

Abstract In this study, the influence of geometric factors such as hole diameter (D), length-to-diameter ratio (L/D), injection angle (α), and lateral expansion angle (β) on film cooling effectiveness of holes made using EDM is experimentally investigated. Nine different cooling configurations were tested on a flat plate wind tunnel at various coolant Reynolds number (Rec) and coolant to mainstream blowing ratio (M). The considered flat plate model incorporates engine sized V-shaped holes. EDM reliability is assessed through a hole qualification process, while effectiveness was measured by the Pressure Sensitive Paint (PSP) technique. Results confirm the suitability of EDM for V-shaped hole manufacturing as long as a correct tolerance on β is prescribed. An accurate qualification of hole morphology is also recommended.

scholarly journals Effect of Mainstream Velocity on the Optimization of a Fan-Shaped Film-Cooling Hole on a Flat Plate

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3573
Author(s):  
Soo-In Lee ◽  
Jin-Young Jung ◽  
Yu-Jin Song ◽  
Jae-Su Kwak
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Density Ratio ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Pressure Sensitive ◽  
Expansion Angle ◽  
Cooling Hole ◽  
Shaped Hole

In this study, the effect of mainstream velocity on the optimization of a fan-shaped hole on a flat plate was experimentally investigated. The experiment was conducted by changing the forward expansion angle (βfwd), lateral expansion angle (βlat), and metering length ratio (Lm/D) of the film-cooling hole. A total of 13 cases extracted using the Box–Behnken method were considered to examine the effect of the shape parameters of the film-cooling hole under a 90 m/s mainstream velocity condition, and the results were compared with the results derived under a mainstream velocity of 20 m/s. One density ratio (DR = 2.0) and a blowing ratio (M) ranging from 1.0 to 2.5 were considered, and the pressure-sensitive paint (PSP) technique was applied for the film-cooling effectiveness (FCE). As a result of the experiment, the optimized hole showed a 49.3% improvement in the overall averaged FCE compared to the reference hole with DR = 2.0 and M = 2.0. As the blowing ratio increased, the hole exit area tended to increase, and this tendency was the same as that in the 20 m/s mainstream condition.

Film Cooling Effectiveness From Two Rows of Compound Angled Cylindrical Holes Using Pressure-Sensitive Paint Technique

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Nian Wang ◽  
Mingjie Zhang ◽  
Chao-Cheng Shiau ◽  
Je-Chin Han
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Density Ratio ◽  
Pressure Sensitive Paint ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Pressure Sensitive ◽  
Staggered Arrangement ◽  
Cylindrical Holes

This study investigates the effects of blowing ratio, density ratio, and spanwise pitch on the flat plate film cooling from two rows of compound angled cylindrical holes. Two arrangements of two-row compound angled cylindrical holes are tested: (a) the first row and the second row are oriented in staggered and same compound angled direction (β = +45 deg for the first row and +45 deg for the second row); (b) the first row and the second row are oriented in inline and opposite direction (β = +45 deg for the first row and −45 deg for the second row). The cooling hole is 4 mm in diameter with an inclined angle of 30 deg. The streamwise row-to-row spacing is fixed at 3d, and the spanwise hole-to-hole (p) is varying from 4d, 6d to 8d for both designs. The film cooling effectiveness measurements were performed in a low-speed wind tunnel in which the turbulence intensity is kept at 6%. There are 36 cases for each design including four blowing ratios (M = 0.5, 1.0, 1.5, and 2.0), three density ratios (DR = 1.0, 1.5, and 2.0), and three hole-to-hole spacing (p/d = 4, 6, and 8). The detailed film cooling effectiveness distributions were obtained by using the steady-state pressure-sensitive paint (PSP) technique. The spanwise-averaged cooling effectiveness are compared over the range of flow parameters. Some interesting observations are discovered including blowing ratio effect strongly depending on geometric design; staggered arrangement of the hole with same orientation does not yield better effectiveness at higher blowing ratio. Currently, film cooling effectiveness correlation of two-row compound angled cylindrical holes is not available, so this study developed the correlations for the inline arrangement of holes with opposing angles and the staggered arrangement of holes with same angles. The results and correlations are expected to provide useful information for the two-row flat plate film cooling analysis.

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.

Film-Cooling Effectiveness on a Gas Turbine Blade Tip Using Pressure-Sensitive Paint

2005 ◽  
Vol 127 (5) ◽  
pp. 521-530 ◽  
Author(s):  
Jaeyong Ahn ◽  
Shantanu Mhetras ◽  
Je-Chin Han
Keyword(s):  
Oxygen Concentration ◽  
Film Cooling ◽  
Pressure Sensitive Paint ◽  
Nitrogen Gas ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Pressure Sensitive ◽  
Blade Tip ◽  
Film Cooling Holes

Effects of the presence of squealer, the locations of the film-cooling holes, and the tip-gap clearance on the film-cooling effectiveness were studied and compared to those for a plane (flat) tip. The film-cooling effectiveness distributions were measured on the blade tip using the pressure-sensitive paint technique. Air and nitrogen gas were used as the film-cooling gases, and the oxygen concentration distribution for each case was measured. The film-cooling effectiveness information was obtained from the difference of the oxygen concentration between air and nitrogen gas cases by applying the mass transfer analogy. Plane tip and squealer tip blades were used while the film-cooling holes were located (a) along the camber line on the tip or (b) along the tip of the pressure side. The average blowing ratio of the cooling gas was 0.5, 1.0, and 2.0. Tests were conducted with a stationary, five-bladed linear cascade in a blow-down facility. The free-stream Reynolds number, based on the axial chord length and the exit velocity, was 1,138,000, and the inlet and the exit Mach numbers were 0.25 and 0.6, respectively. Turbulence intensity level at the cascade inlet was 9.7%. All measurements were made at three different tip-gap clearances of 1%, 1.5%, and 2.5% of blade span. Results show that the locations of the film-cooling holes and the presence of squealer have significant effects on surface static pressure and film-cooling effectiveness, with film-cooling effectiveness increasing with increasing blowing ratio.

Combined Effects of Freestream Pressure Gradient and Density Ratio on the Film Cooling Effectiveness of Round and Shaped Holes on a Flat Plate

2016 ◽  
Author(s):  
Kyle R. Vinton ◽  
Travis B. Watson ◽  
Lesley M. Wright ◽  
Daniel C. Crites ◽  
Mark C. Morris ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Flat Plate ◽  
Film Cooling ◽  
Density Ratio ◽  
Round Hole ◽  
Combined Effects ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Lift Off

The combined effects of a favorable, mainstream pressure gradient and coolant-to-mainstream density ratio have been investigated. Detailed film cooling effectiveness distributions have been obtained on a flat plate with either cylindrical (θ = 30°) or laidback, fan-shaped holes (θ = 30°, β = γ = 10°) using the pressure sensitive paint (PSP) technique. In a low speed wind tunnel, both non-accelerating and accelerating flows were considered while the density ratio varied from 1–4. In addition, the effect of blowing ratio was considered, with this ratio varying from 0.5 to 1.5. The film produced by the shaped hole outperformed the round hole under the presence of a favorable pressure gradient for all blowing and density ratios. At the lowest blowing ratio, in the absence of freestream acceleration, the round holes outperformed the shaped holes. However, as the blowing ratio increases, the shaped holes prevent lift-off of the coolant and offer enhanced protection. The effectiveness afforded by both the cylindrical and shaped holes, with and without freestream acceleration, increased with density ratio.

Effect of Hole Diameter on Nozzle Endwall Film Cooling and Associated Phantom Cooling

2015 ◽  
Author(s):  
Luzeng Zhang ◽  
Juan Yin ◽  
Kevin Liu ◽  
Moon Hee-Koo
Keyword(s):  
Film Cooling ◽  
High Speed ◽  
Leading Edge ◽  
Suction Side ◽  
Hole Diameter ◽  
Two Dimensional ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Injection Angle ◽  
Blowing Ratio

Flow fields near the turbine nozzle endwall are highly complex due to the passage vortices and endwall cross flows. Consequently, it is challenging to provide proper cooling to the endwall surfaces. An effective way to cool the endwall is to have film cooling holes forward of the leading edge, often called “inlet-film cooling”. This paper presents the results of an experimental investigation on how the film hole diameter affects the film effectiveness on nozzle endwall and associated phantom cooling effectiveness on airfoil suction side. The measurements were conducted in a high speed linear cascade, which consists of three nozzle vanes and four flow passages. Double staggered rows of film injections, which were located upstream from the nozzle leading edge, provided cooling to the contoured endwall surfaces. Film cooling effectiveness on the endwall surface and corresponding phantom cooling effectiveness on the airfoil suction side were measured separately with a Pressure Sensitive Paint (PSP) technique through the mass transfer analogy. Four different film hole diameters with the same injection angle and the same pitch to diameter ratio were studied for up to six different MFR’s (mass flow ratios). Two dimensional film effectiveness distributions on the endwall surface and two dimensional phantom cooling distributions on the airfoil suction side are presented. Film/phantom cooling effectiveness distributions are pitchwise/spanwise averaged along the axial direction and also presented. The results indicate that both the endwall film effectiveness and the suction side phantom cooling effectiveness increases with the hole diameter (as decreases in blowing ratio for a given MFR) up to a specific diameter, then starts decreasing. An optimal value of the film hole diameter (blowing ratio) for the given injection angle is also suggested based on current study.

Film Cooling Effectiveness Distributions on a Flat Plate With a Double Hole Geometry Using PSP

2011 ◽  
Author(s):  
Lesley M. Wright ◽  
Evan L. Martin
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Surface Film ◽  
Density Ratio ◽  
Cooling Effectiveness ◽  
Freestream Velocity ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
Blowing Ratio ◽  
Hole Geometry

Detailed film cooling effectiveness distributions are obtained on a flat plate using the pressure sensitive paint (PSP) technique. The effects of average blowing ratio (M = 0.25–1.0) and coolant – to – mainstream density ratio (DR = 1.0–1.4) are evaluated in a low speed wind tunnel with a freestream velocity of 8.5 m/s and a freestream turbulence intensity of 6.8%. The coolant – to – mainstream density ratio is varied by using either nitrogen (DR = 1.0) or argon (DR = 1.4) as the coolant gases. The double hole geometry consists of a row of simple angle (θ = 35°), cylindrical holes coupled with one row of compound angle holes (θ = 45°, β = 50°). With the selected geometry, the compound holes effectively weaken the counter rotating vortex pair formed within the traditional simple angle hole. Therefore, the surface film cooling effectiveness is increased compared to a single row of simple angle film cooling holes. While increasing the blowing ratio decreases the film cooling effectiveness, the severity of the film cooling effectiveness reduction is less than with the single row of holes.

Interaction of Flow and Film-Cooling Effectiveness Between Double-Jet Film-Cooling Holes With Various Spanwise Distances

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Jiaxu Yao ◽  
Jin Xu ◽  
Ke Zhang ◽  
Jiang Lei ◽  
Lesley M. Wright
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Density Ratio ◽  
Vortex Pair ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Film Cooling Holes ◽  
Two Jets ◽  
Compound Angle

The interaction of flow and film-cooling effectiveness between jets of double-jet film-cooling (DJFC) holes on a flat plate is studied experimentally. The time-averaged flow field in several axial positions (X/d = −2.0, 1.0, and 5.0) is obtained through a seven-hole probe. The downstream film-cooling effectiveness on the flat plate is measured by pressure sensitive paint (PSP). The inclination angle (θ) of all the holes is 35 deg, and the compound angle (β) is ±45 deg. Effects of the spanwise distance (p = 0, 0.5d, 1.0d, 1.5d, and 2.0d) between the two interacting jets of DJFC holes are studied, while the streamwise distance (s) is kept as 3d. The blowing ratio (M) varies as 0.5, 1.0, 1.5, and 2.0. The density ratio (DR) is maintained at 1.0. Results show that the interaction between the two jets of DJFC holes has different effects at different spanwise distances. For a small spanwise distance (p/d = 0), the interaction between the jets presents a pressing effect. The downstream jet is pressed down and kept attached to the surface by the upstream one. The effectiveness is not sensitive to blowing ratios. For mid-spanwise distances (p/d = 0.5 and 1.0), the antikidney vortex pair dominates the interaction and pushes both of the jets down, thus leading to better coolant coverage and higher effectiveness. As the spanwise distance becomes larger (p/d ≥ 1.5), the pressing effect almost disappears, and the antikidney vortex pair effect is weaker. The jets separate from each other and the coolant coverage decreases. At a higher blowing ratio, the interaction between the jets of DJFC holes happens later.

Experimental Flow Field Investigations of Nozzle Film Cooling Scheme on a Flat Plate Using Stereo PIV

2013 ◽  
Author(s):  
Yingjie Zheng ◽  
Ibrahim Hassan
Keyword(s):  
Flow Field ◽  
Flat Plate ◽  
Film Cooling ◽  
Density Ratio ◽  
Cylindrical Hole ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Field Investigations ◽  
Nozzle Hole

This paper presents experimental flow field investigations of a film cooling scheme, referred to as nozzle scheme, on a flat plate using stereo PIV. The nozzle scheme has a cylindrical hole and internal obstacles to change the velocity distribution near the hole exit and hence the jet-mainstream interaction. Counter-rotating vortex pair (CRVP) is known to be one of the detrimental effects that affect the film cooling effectiveness. Previous CFD simulations demonstrated nozzle hole’s capability of reducing CRVP strength and enhancing film cooling effectiveness in comparison with a normal cylindrical hole. The present study examines the nozzle hole flow filed experimentally at blowing ratio ranged from 0.5 to 2.0 and compares with cylindrical hole. The experiments were conducted in a low-speed wind tunnel with a mainstream Reynolds number of 115,000 and the density ratio was 1.0 during all the investigations. The experimental results show that nozzle hole reduces streamwise vorticity of CRVP by an average of 55% at low blowing ratio, and 34%–40% at high blowing ratios. The velocity field and vorticity field of nozzle jet are compared with cylindrical jet. The result reveals that the nozzle jet forms a round bulk in contrast to the kidney shape jet core in cylindrical hole case. In addition, it is found that CRVP strength may not be a primary contributor to the jet lift-off.

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