Improved Trench Film Cooling With Shaped Trench Outlets

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Habeeb Idowu Oguntade ◽  
Gordon E. Andrews ◽  
A. D. Burns ◽  
Derek B. Ingham ◽  
Mohammed Pourkashanian
Keyword(s):  
Flat Plate ◽  
Mass Flow ◽  
Film Cooling ◽  
Cross Flow ◽  
Suction Side ◽  
Experimental Results ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Vertical Slot ◽  
Cooling Hole

The influence of the shape of the downstream edge of trench film cooling hole outlets on film cooling effectiveness was investigated using CFD for flat plate film cooling. A 90 deg trench outlet wall with impinging 30 deg film cooling jets results in improved transverse film cooling effectiveness but produces a vertical slot jet into the cross flow, which is not the best aerodynamics for optimum film cooling. It was considered that improvements in the cooling effectiveness would occur if the trailing edge of the trench outlet produced a flow that was inclined in the direction of the crossflow. Beveled and filleted trench outlet shapes were investigated. The CFD predictions were shown to predict well the conventional sharp edged trench outlet experimental results for a flat plate geometry. The flat plate CFD predictions were also shown to predict the experimental results for trench cooling on the suction side of a turbine vane, where the local curvature was small relative to the trench width. The beveled and filleted trench outlets were predicted to suppress the vertical jet momentum and give a Coanda effect that allowed the cooling air to attach to the downstream wall surface. This produced an improved transverse spread of the coolant. Also, it was predicted that reducing the coolant mass flow per hole and increasing the number of rows of holes gave, for the same total coolant mass flow and the same surface area, a superior surface averaged cooling effectiveness.

Geometrical Optimization and Experimental Validation of a Tripod Film Cooling Hole With Asymmetric Side Holes

2014 ◽  
Author(s):  
Zhongran Chi ◽  
Chang Han ◽  
Xueying Li ◽  
Jing Ren ◽  
Hongde Jiang
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Experimental Results ◽  
Geometrical Parameters ◽  
Vortex System ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Optimum Configuration ◽  
Optimization Study ◽  
Cooling Hole

A tripod cylindrical film hole with asymmetric side holes is studied numerically and experimentally on a flat plate for higher film cooling effectiveness. Firstly, the influences of geometrical parameters are studied and the optimum configurations of the asymmetric tripod hole are found in a DoE optimization study based on an improved numerical model for film cooling prediction, in which more than one hundred 3D CFD simulations are carried out. Then one optimum configuration of the asymmetric tripod hole is examined experimentally using pressure-sensitive paint (PSP) measurements, and compared against the experimental results of the simple cylindrical film hole and a well-designed shaped film hole. The flow and heat transfer characteristics of the asymmetric tripod holes were explored from the DoE results. The side holes can form a shear vortex system or an anti-kidney vortex system when proper spanwise distances of them are adopted, which laterally transports the coolant and form a favorable coolant coverage. According to the experimental results, the cooling performance of the optimized asymmetric tripod hole is significantly better than that of the simple cylindrical hole, especially at high blowing ratios. And the optimized asymmetric tripod hole can provide almost the same or even higher film cooling effectiveness on the flat plate compared with the shaped hole in the same flow conditions.

Improved Trench Film Cooling With Shaped Trench Outlets

2011 ◽  
Author(s):  
Habeeb Idowu Oguntade ◽  
Gordon E. Andrews ◽  
Alan Burns ◽  
Derek B. Ingham ◽  
Mohammed Pourkashanian
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Cross Flow ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Vertical Slot ◽  
Superior Surface ◽  
Cooling Air ◽  
Computational Predictions

This paper presents the influence of the shaped trailing edge of trench outlets on film cooling effectiveness and aerodynamics. A 90° outlet wall to a trench will give a vertical slot jet into the cross flow and it was considered that improvements in the cooling effectiveness would occur if the trailing edge of the trench outlet was bevelled or filleted. CFD approach was used for these investigations which started with the predictions of the conventional sharp edged trench outlet for two experimental geometries. The computational predictions for the conventional sharp edged trench outlet were shown to have good agreement with the experimental data for two experimental geometries. The shaped trailing edge of the trench outlet was predicted to improve the film cooling effectiveness. The bevelled and filleted trench outlets were predicted to further suppress vertical jet momentum and give a Coanda effect that allowed the cooling air to attach to the downstream wall surface with a better transverse spread of the coolant film. The new trench outlet geometries would allow a reduction in film cooling mass flow rate for the same cooling effectiveness. Also, it was predicted that reducing the coolant mass flow per hole and increasing the number of holes gave, for the same total coolant mass flow, a much superior surface averaged cooling effectiveness for the same cooled surface area.

Geometrical Optimization and Experimental Validation of a Tripod Film Cooling Hole With Asymmetric Side Holes

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Zhongran Chi ◽  
Jing Ren ◽  
Hongde Jiang ◽  
Shusheng Zang
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Experimental Results ◽  
Geometrical Parameters ◽  
Vortex System ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Optimum Configuration ◽  
Optimization Study ◽  
Cooling Hole

A tripod cylindrical film hole with asymmetric side holes is studied numerically and experimentally on a flat plate for higher film cooling effectiveness. First, the influences of geometrical parameters are studied and the optimum configurations of the asymmetric tripod hole are found in a design of experiments (DoE) optimization study based on an improved numerical model for film cooling prediction, in which more than 100 3D computational fluid dynamics (CFD) simulations are carried out. Then, one optimum configuration of the asymmetric tripod hole is examined experimentally using pressure-sensitive paint (PSP) measurements and compared to the experimental results of the simple cylindrical film hole and a well-designed shaped film hole. The flow and heat transferring characteristics of the asymmetric tripod holes were explored from the DoE results. The side holes can form a shear vortex system or an antikidney vortex system when proper spanwise distances between them are adopted, which laterally transports the coolant and form a favorable coolant coverage. According to the experimental results on flat plate, the optimal configuration of the asymmetric tripod hole is significantly better than cylindrical hole, especially at high blowing ratios. Furthermore, it can provide equivalent or even higher film cooling effectiveness than a well-designed shaped hole.

Effects of Double Wall Cooling Configuration and Conditions on Performance of Full-Coverage Effusion Cooling

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Nathan Rogers ◽  
Zhong Ren ◽  
Warren Buzzard ◽  
Brian Sweeney ◽  
Nathan Tinker ◽  
...  
Keyword(s):  
Film Cooling ◽  
Cross Flow ◽  
Hole Array ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Full Coverage ◽  
Cooling Hole ◽  
Double Wall

Experimental results are presented for a double wall cooling arrangement which simulates a portion of a combustor liner of a gas turbine engine. The results are collected using a new experimental facility designed to test full-coverage film cooling and impingement cooling effectiveness using either cross flow, impingement, or a combination of both to supply the film cooling flow. The present experiment primarily deals with cross flow supplied full-coverage film cooling for a sparse film cooling hole array that has not been previously tested. Data are provided for turbulent film cooling, contraction ratio of 1, blowing ratios ranging from 2.7 to 7.5, coolant Reynolds numbers based on film cooling hole diameter of about 5000–20,000, and mainstream temperature step during transient tests of 14 °C. The film cooling hole array consists of a film cooling hole diameter of 6.4 mm with nondimensional streamwise (X/de) and spanwise (Y/de) film cooling hole spacing of 15 and 4, respectively. The film cooling holes are streamwise inclined at an angle of 25 deg with respect to the test plate surface and have adjacent streamwise rows staggered with respect to each other. Data illustrating the effects of blowing ratio on adiabatic film cooling effectiveness and heat transfer coefficient are presented. For the arrangement and conditions considered, heat transfer coefficients generally increase with streamwise development and increase with increasing blowing ratio. The adiabatic film cooling effectiveness is determined from measurements of adiabatic wall temperature, coolant stagnation temperature, and mainstream recovery temperature. The adiabatic wall temperature and the adiabatic film cooling effectiveness generally decrease and increase, respectively, with streamwise position, and generally decrease and increase, respectively, as blowing ratio becomes larger.

Improving Film Cooling Performance Using Airfoil Contouring

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Atul Kohli ◽  
David G. Bogard
Keyword(s):  
Film Cooling ◽  
Suction Side ◽  
Design Tool ◽  
Optimization Process ◽  
Navier Stokes ◽  
Spanwise Direction ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Hole ◽  
Cfd Analyses

In this study, a computational fluid dynamics (CFD)-based optimization process is used to change the contour of the airfoil near a suction-side cooling hole in order to improve its film effectiveness characteristics. An overview of the optimization process, which includes automated geometry, grid generation, and CFD analyses, is provided. From the results for the optimized geometry, it is clear that the detachment of the cooling jet is much reduced and the cooling jet spread in the spanwise direction is increased substantially. The new external contour was then tested in a low-speed wind tunnel to provide a direct measure of the predictive capability. Comparisons to verification test data indicate that good agreement was achieved for both pressure and film cooling effectiveness behavior. This study proves that despite its limitations, current Reynolds averaged Navier-Stokes (RANS) methodology can be used a viable design tool and lead to innovative concepts for improving film cooling effectiveness.

An Experimental Investigation of an Anti-Vortex Film Cooling Geometry Under Low and High Turbulence Conditions

2012 ◽  
Author(s):  
Sebastian Schulz ◽  
Simon Maier ◽  
Jeffrey P. Bons
Keyword(s):  
Flat Plate ◽  
Secondary Flow ◽  
Infrared Thermography ◽  
Film Cooling ◽  
Streamwise Direction ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Cooling Hole ◽  
High Turbulence

In an attempt to abate the detrimental jet vorticity and lift-off effects at high blowing ratios, the objective of the present study is to investigate the impact of an anti-vortex film cooling hole design on the film cooling effectiveness and the secondary flow field. Furthermore, the influence of low and high turbulence levels is studied with Tu ≈ .0.7% and ≈ 10%, respectively. For the experiments infrared thermography and particle image velocimetry (PIV) are employed. The experiments are conducted in a subsonic wind tunnel at a Reynolds number of 11000 based on the film cooling hole diameter. A flat plate model with an array of three cylindrical primary holes with secondary offshoots to each side represents the anti-vortex geometry. The cylindrical hole arrangement with a diameter of 17.5 mm is inclined at 30° in streamwise direction, with the anti-vortex holes branching off from the primary hole base in a 21° angle. Information from a flat plate with six cylindrical holes of 17.5 mm in diameter inclined at 30 in streamwise direction is used as baseline for comparison. The primary hole spacing was 4.75 and 3 hole diameters, respectively. Results are presented for blowing ratios of 1 and 2 with a constant density ratio of 1.1. The PIV measurements are taken in two planes perpendicular to the flow direction to record the secondary flow structures. The results of the infrared thermography show a strong decrease in film cooling effectiveness as high turbulence levels occur, especially for low blowing ratios. For higher blowing ratios low and high turbulence levels have similar effects on film cooling effectiveness. A significant improvement in film cooling performance is displayed by the anti-vortex design over the standard circular hole arrangement for every blowing ratio. The effectiveness results reveal an improved lateral spreading of the coolant with coolant jets staying attached throughout the series of experiments. By remaining inside the boundary layer, the effects of a high turbulent freestream on film cooling performance is less. The PIV results unveil information of a new vortex pair on either side of the primary hole kidney vortex. Especially at high blowing ratios the results indicate, that the anti-vortex hole design promotes the interaction between the vortical structures, explaining the increased lateral film effectiveness results. The factor which lends to the superior performance and credibility of the studied anti-vortex design is that the results are obtained for 35% less mass flow than the baseline.

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.

Improving Film Cooling Performance Using Airfoil Contouring

2006 ◽  
Author(s):  
Atul Kohli ◽  
David G. Bogard
Keyword(s):  
Film Cooling ◽  
Suction Side ◽  
Design Tool ◽  
Optimization Process ◽  
Spanwise Direction ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Hole ◽  
Cfd Analyses ◽  
Low Speed Wind Tunnel

In this study, a CFD-based optimization process is used to change the contour of the airfoil near a suction side cooling hole in order to improve its film effectiveness characteristics. An overview of the optimization process, which includes automated geometry, grid generation and CFD analyses is provided. From the results for the optimized geometry it is clear that the detachment of the cooling jet is much reduced and the cooling jet spread in the spanwise direction is increased substantially. The new external contour was then tested in a low-speed wind tunnel to provide a direct measure of the predictive capability. Comparisons to verification test data indicate that good agreement was achieved for both pressure and film cooling effectiveness behavior. This study proves that despite its limitations, current RANS methodology can be used a viable design tool and lead to innovative concepts for improving film cooling effectiveness.

Film Cooling With Swirling Coolant Flow on a Flat Plate and the Endwall of High-Loaded First Nozzle

2014 ◽  
Author(s):  
Kenichiro Takeishi ◽  
Yutaka Oda ◽  
Shinpei Kondo
Keyword(s):  
Wind Tunnel ◽  
Flat Plate ◽  
Film Cooling ◽  
Wind Tunnel Test ◽  
Impinging Jets ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Hole ◽  
Film Cooling Holes ◽  
Cooling Air

This paper describes an experimental study on the film cooling effectiveness of circular and fan-shaped film cooling holes with a swirling film coolant injected through a flat plate and the endwall of a high-loaded first nozzle. The experiments were conducted using a flat plate wind tunnel and a two-dimensional vane cascade, which is designed based on the first-stage vane of an Energy Efficient Engine (E3) studied under a NASA project. The film cooling effectiveness on a flat plate wind tunnel and the endwall of the enlarged first nozzle of the E3 turbine was measured using pressure sensitive paint (PSP) techniques. The experimental results indicate that the film cooling effectiveness of a circular hole improved by increasing the angle θ of two impinging jets inside the cavity, which are used both for cooling the internal wall and generating a swirling motion in the film coolant. In contrast, it was found that there exist optimal jet angles of θ = 20° for a circular film cooling hole, θ = 5–10° for a flat plate wind tunnel test, and θ = 15° for the cascade test conducted using a fan-shaped film cooling hole. Thus the new film cooling method using swirling cooling air has been demonstrated to maintain high film cooling effectiveness even under such a complicated flow field.

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.

Sign in / Sign up

Export Citation Format

Share Document