Film cooling characteristics on a grooved surface with different injection orientation angles

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Peng Yang ◽  
Guangchao Li ◽  
Jianyong Zhu
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Orientation Angle ◽  
Hole Injection ◽  
Blowing Ratio ◽  
Reverse Trend ◽  
Grooved Surface ◽  
Shaped Hole

Abstract The film effectiveness was investigated on a grooved surface with the injection orientation angles of 30°, 90°, and 150° at the blowing ratios of 0.5, 0.8, 1.1, and 1.4. The injection orientation angle and the groove on the surface caused the effect of the various and irregular shaped hole injection due to the different orientation injection. The results showed that the new phenomenon of film effectiveness distributions was found on the grooved surface compared with the flat plate case. Film effectiveness distributions for the β = 30° were found to be the discontinuous strips. The surface averaged film effectiveness with the orientation angle of 30° was found to decrease with the increase of the blowing ratio. Additionally, the reverse trend was observed with the orientation angle of 150°. The film effectiveness with the orientation angle of 90° only slightly changed with the increase of the blowing ratio.

Film cooling characteristics on a grooved surface with different injection orientation angles

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Peng Yang ◽  
Guangchao Li ◽  
Jianyong Zhu
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Orientation Angle ◽  
Hole Injection ◽  
Blowing Ratio ◽  
Reverse Trend ◽  
Grooved Surface ◽  
Shaped Hole

AbstractThe film effectiveness was investigated on a grooved surface with the injection orientation angles of 30°, 90°, and 150° at the blowing ratios of 0.5, 0.8, 1.1, and 1.4. The injection orientation angle and the groove on the surface caused the effect of the various and irregular shaped hole injection due to the different orientation injection. The results showed that the new phenomenon of film effectiveness distributions was found on the grooved surface compared with the flat plate case. Film effectiveness distributions for the β = 30° were found to be the discontinuous strips. The surface averaged film effectiveness with the orientation angle of 30° was found to decrease with the increase of the blowing ratio. Additionally, the reverse trend was observed with the orientation angle of 150°. The film effectiveness with the orientation angle of 90° only slightly changed with the increase of the blowing ratio.

Experimental Investigation of Film Cooling Performance on Blade Endwall with Diffusion Slot Holes and Stator-Rotor Purge Flow

2021 ◽  
pp. 1-28
Author(s):  
Zhi-Qiang Yu ◽  
Jianjun Liu ◽  
Chen Li ◽  
Baitao An ◽  
Guang-Yao Xu
Keyword(s):  
Film Cooling ◽  
Flow Direction ◽  
Cross Flow ◽  
Orientation Angle ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Pressure Surface ◽  
Blowing Ratio ◽  
Shaped Hole

Abstract This paper focuses on the influences of the discrete hole shape and layout on the blade endwall film cooling effectiveness. The diffusion slot hole was first applied to the blade endwall and compared with the fan-shaped hole. The effect of upstream purge slot injection on the film cooling performance of the discrete hole was also investigated. Experiments were performed in a linear cascade with a exit Reynolds number of 2.64×105. The film cooling effectiveness on the blade endwall were measured by the pressure sensitive paint technique. Results indicate that the diffusion slot hole significantly increases the film cooling effectiveness on the blade endwall compared to the fan-shaped hole, especially at high blowing ratio. The maximum relative increment of the cooling effectiveness is over 40%. The layout with the discrete holes arranged lining up with the tangent direction of the blade profile offset curves exhibits a comparable film cooling effectiveness with the layout with the discrete holes arranged according to the cross-flow direction. The film cooling effectiveness on the pressure surface corner is remarkably enhanced by deflecting the hole orientation angle towards the pressure surface. The combination of purge slot and diffusion slot holes supplies a full coverage film cooling for the entire blade endwall at coolant mass flow ratio of the purge slot of 1.5% and blowing ratio of 2.5. In addition, the slot injection leads to a non-negligible influence on the cooling performance of the discrete holes near the separation line.

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.

Experimental Investigation of Adiabatic Film Cooling Effectiveness Over a Circular Fan and Laidback Fan Shaped Hole Flat Plate Test Models

2015 ◽  
Author(s):  
Giridhara Babu Yepuri ◽  
Felix Jesuraj ◽  
Suresh Batchu ◽  
Kesavan Venkataraman
Keyword(s):  
Experimental Investigation ◽  
Flat Plate ◽  
Film Cooling ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Test Models ◽  
Plate Models ◽  
Shaped Hole ◽  
Hole Model

The experimental investigation of adiabatic film cooling effectiveness is carried out on a flat plates with 4:1 scaled up hole geometries, similar to that of typical turbine nozzle guide vane film cooling holes. Under this study, three flat plate models are considered with the two rows of holes having circular, fan and laidback fan shapes arranged in a staggered manner. These flat plate models are generated using solid works design software and fabricated using low thermal conductivity nylon based material using RPT technique. The mass flow results indicated the average nominal coefficient of discharge for the cooling holes as 0.71, for all these three models based on the inlet hole area and length of the holes. The laterally averaged adiabatic film cooling effectiveness is found along the stream wise direction at a density ratio of 1.62 by varying the blowing ratio in the range of 0.5 to 2.5. The surface temperatures of the test models are captured using the infrared camera, to evaluate the film cooling effectiveness. The experimentally evaluated results shows that, there is no increase in cooling effectiveness for the blowing ratio of 2.0 to 2.5 in the stream wise direction up to the X/d of 25 and there is a marginal increase above the X/d of 25 in the cases of these type of two row circular and Fan shaped hole models. Where as in the Laidback fan shaped hole model, the increase in cooling effectiveness is found significant up to the blowing ratio of 2.5 in the considered range. From the comparative results of adiabatic film cooling effectiveness of these three models, the laidback fan shaped hole model shows the higher film cooling effectiveness than the circular and fan shaped holes model at all the considered blowing ratios.

The Effect of Compound Angle on Nozzle Pressure Side Film Cooling

2009 ◽  
Author(s):  
Luzeng Zhang ◽  
Juan Yin ◽  
Hee Koo Moon
Keyword(s):  
Film Cooling ◽  
Operating Conditions ◽  
The Other ◽  
Hole Injection ◽  
Pressure Side ◽  
Blowing Ratio ◽  
Test Models ◽  
Nozzle Pressure ◽  
Shaped Hole ◽  
Compound Angle

The effect of film cooling hole compound angle on nozzle pressure side film cooling effectiveness was experimentally investigated using a single row of shaped hole injection. The engine operating conditions were simulated in a scaled warm cascade, which was built based on industrial gas turbine nozzle vanes. Local film effectiveness measurements were made using a computerized pressure sensitive paint (PSP) technique. Nitrogen gas was used to simulate cooling flow as well as a tracer gas to indicate oxygen concentration such that film effectiveness by the mass transfer analogy. Three separate nozzle test models were fabricated, which have same cooling supply plenum configurations. One of them has a row of shaped hole on the pressure surface without a compound angle. The other two test models have same size film holes at the same location, but one with a 30-degree compound angle in co-flow and the other in counter-flow direction to the cooling supply. Four cooling mass flow ratios (MFR, blowing ratio) were studied for each of the nozzle test models and two-dimensional film effectiveness distributions were measured. Then the film effectiveness distributions were spanwise averaged for comparison. For all three cases, the overall film effectiveness increased with the MFR (or the blowing ratio), but not significantly. Film effectiveness by a compound angle injection is higher compared to those without a compound angle near the injection, further downstream the difference is insignificant.

scholarly journals Large Eddy Simulation of Film Cooling Involving Compound Angle Holes: Comparative Study of LES and RANS

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 198
Author(s):  
Seung Il Baek ◽  
Joon Ahn
Keyword(s):  
Large Eddy Simulation ◽  
Film Cooling ◽  
Orientation Angle ◽  
Turbulence Models ◽  
Film Cooling Effectiveness ◽  
Injection Angle ◽  
Blowing Ratio ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Compound Angle

A large eddy simulation (LES) was performed for film cooling in the gas turbine blade involving spanwise injection angles (orientation angles). For a streamwise coolant injection angle (inclination angle) of 35°, the effects of the orientation angle were compared considering a simple angle of 0° and 30°. Two ratios of the coolant to main flow mass flux (blowing ratio) of 0.5 and 1.0 were considered and the experimental conditions of Jung and Lee (2000) were adopted for the geometry and flow conditions. Moreover, a Reynolds averaged Navier–Stokes simulation (RANS) was performed to understand the characteristics of the turbulence models compared to those in the LES and experiments. In the RANS, three turbulence models were compared, namely, the realizable k-ε, k-ω shear stress transport, and Reynolds stress models. The temperature field and flow fields predicted through the RANS were similar to those obtained through the experiment and LES. Nevertheless, at a simple angle, the point at which the counter-rotating vortex pair (CRVP) collided on the wall and rose was different from that in the experiment and LES. Under the compound angle, the point at which the CRVP changed to a single vortex was different from that in the LES. The adiabatic film cooling effectiveness could not be accurately determined through the RANS but was well reflected by the LES, even under the compound angle. The reattachment of the injectant at a blowing ratio of 1.0 was better predicted by the RANS at the compound angle than at the simple angle. The temperature fluctuation was predicted to decrease slightly when the injectant was supplied at a compound angle.

The Effect of Freestream Turbulence on Film Cooling Adiabatic Effectiveness

2002 ◽  
Author(s):  
James E. Mayhew ◽  
James W. Baughn ◽  
Aaron R. Byerley
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Density Ratio ◽  
Main Flow ◽  
Freestream Turbulence ◽  
Coverage Area ◽  
Liquid Crystal Thermography ◽  
Blowing Ratio ◽  
Adiabatic Effectiveness ◽  
Cooling Air

The film-cooling performance of a flat plate in the presence of low and high freestream turbulence is investigated using liquid crystal thermography. High-resolution distributions of the adiabatic effectiveness are determined over the film-cooled surface of the flat plate using the hue method and image processing. Three blowing rates are investigated for a model with three straight holes spaced three diameters apart, with density ratio near unity. High freestream turbulence is shown to increase the area-averaged effectiveness at high blowing rates, but decrease it at low blowing rates. At low blowing ratio, freestream turbulence clearly reduces the coverage area of the cooling air due to increased mixing with the main flow. However, at high blowing ratio, when much of the jet has lifted off in the low turbulence case, high freestream turbulence turns its increased mixing into an asset, entraining some of the coolant that penetrates into the main flow and mixing it with the air near the surface.

Film Cooling From Novel Sister Shaped Single-Holes

2014 ◽  
Author(s):  
Siavash Khajehhasani ◽  
Bassam Jubran
Keyword(s):  
Film Cooling ◽  
Three Dimensional ◽  
Lateral Spreading ◽  
Navier Stokes ◽  
The Novel ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Shaped Hole ◽  
Lift Off

A numerical investigation of the film cooling performance from novel sister shaped single-holes (SSSH) is presented in this paper and the obtained results are compared with a single cylindrical hole, a forward diffused shaped hole, as well as discrete sister holes. Three types of the novel sister shaped single-hole schemes namely downstream, upstream and up/downstream SSSH, are designed based on merging the discrete sister holes to the primary hole in order to reduce the jet lift-off effect and increase the lateral spreading of the coolant on the blade surface as well as a reduction in the amount of coolant in comparison with discrete sister holes. The simulations are performed using three-dimensional Reynolds-Averaged Navier Stokes analysis with the realizable k–ε model combined with the standard wall function. The upstream SSSH demonstrates similar film cooling performance to that of the forward diffused shaped hole for the low blowing ratio of 0.5. While it performs more efficiently at M = 1, where the centerline and laterally averaged effectiveness results improved by 70% and 17%, respectively. On the other hand, the downstream and up/downstream SSSH schemes show a considerable improvement in film cooling performance in terms of obtaining higher film cooling effectiveness and less jet lift-off effect as compared with the single cylindrical and forward diffused shaped holes for both blowing ratios of M = 0.5 and 1. For example, the laterally averaged effectiveness for the downstream SSSH configuration shows an improvement of approximately 57% and 110% on average as compared to the forward diffused shaped hole for blowing ratios of 0.5 and 1, respectively.

Investigations on the Influence of Rib Orientation Angle on Film Cooling Performance of Compound Holes

2018 ◽  
Author(s):  
Lin Ye ◽  
Cun-liang Liu ◽  
Hai-yong Liu ◽  
Hui-ren Zhu ◽  
Jian-xia Luo
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Discharge Coefficient ◽  
Orientation Angle ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio

To investigate the effects of the inclined ribs on internal flow structure in film hole and the film cooling performance on outer surface, experimental and numerical studies are conducted on the effects of rib orientation angle on film cooling of compound cylindrical holes. Three coolant channel cases, including two ribbed cross-flow channels (135° and 45° angled ribs) and the plenum case, are studied under three blowing ratios (0.5, 1.0 and 2.0). 2D contours of film cooling effectiveness as well as heat transfer coefficient were measured by transient liquid crystal measurement technique (TLC). The steady RANS simulations with realizable k-ε turbulence model and enhanced wall treatment were performed. The results show that the spanwise width of film coverage is greatly influenced by the rib orientation angle. The spanwise width of the 45° rib case is obviously larger than that of the 135° rib case under lower blowing ratios. When the blowing ratio is 1.0, the area-averaged cooling effectiveness of the 135° rib case and the 45° rib case are higher than that of the plenum case by 38% and 107%, respectively. With the increase of blowing ratio, the film coverage difference between different rib orientation cases becomes smaller. The 45° rib case also produces higher heat transfer coefficient, which is higher than the 135° rib case by 3.4–8.7% within the studied blowing ratio range. Furthermore, the discharge coefficient of the 45° rib case is the lowest among the three cases. The helical motion of coolant flow is observed in the hole of 45° rib case. The jet divides into two parts after being blown out of the hole due to this motion, which induces strong velocity separation and loss. For the 135° rib case, the vortex in the upper half region of the secondary-flow channel rotates in the same direction with the hole inclination direction, which leads to the straight streamlines and thus results in lower loss and higher discharge coefficient.

Mechanism of Film Cooling with One Inlet and Double Outlet Hole Injection at Various Turbulence Intensities

2018 ◽  
Vol 35 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Guangchao Li ◽  
Yukai Chen ◽  
Zhihai Kou ◽  
Wei Zhang ◽  
Guochen Zhang
Keyword(s):  
Turbulence Intensity ◽  
Film Cooling ◽  
Hole Injection ◽  
Spanwise Direction ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Outlet Hole ◽  
Cylindrical Holes ◽  
High Turbulence

AbstractThe trunk-branch hole was designed as a novel film cooling concept, which aims for improving film cooling performance by producing anti-vortex. The trunk-branch hole is easily manufactured in comparison with the expanded hole since it consists of two cylindrical holes. The effect of turbulence on the film cooling effectiveness with a trunk-branch hole injection was investigated at the blowing ratios of 0.5, 1.0, 1.5 and 2.0 by numerical simulation. The turbulence intensities from 0.4 % to 20 % were considered. The realizable$k - \varepsilon $turbulence model and the enhanced wall function were used. The more effective anti-vortex occurs at the low blowing ratio of 0.5 %. The high turbulence intensity causes the effectiveness evenly distributed in the spanwise direction. The increase of turbulence intensity leads to a slight decrease of the spanwise averaged effectiveness at the low blowing ratio of 0.5, but a significant increase at the high blowing ratios of 1.5 and 2.0. The optimal blowing ratio of the averaged surface effectiveness is improved from 1.0 to 1.5 when the turbulence intensity increases from 0.4 % to 20 %.

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