A Numerical Study on Improving Large Angle Film Cooling Performance through the Use of Sister Holes

2009 ◽  
Vol 55 (7) ◽  
pp. 634-653 ◽  
Author(s):  
Marc J. Ely ◽  
B. A. Jubran
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Large Angle ◽  
Cooling Performance

Experimental and Numerical Study on the Effects of the Relative Position of Film Hole and Orientation Ribs on the Film Cooling With Ribbed Cross-Flow Coolant Channel

2020 ◽  
Author(s):  
Bingran Li ◽  
Cunliang Liu ◽  
Lin Ye ◽  
Huiren Zhu ◽  
Fan Zhang
Keyword(s):  
Heat Transfer ◽  
Relative Position ◽  
Film Cooling ◽  
Numerical Study ◽  
Cross Flow ◽  
Internal Cooling ◽  
Transfer Coefficients ◽  
Cooling Performance ◽  
Heat Transfer Coefficients ◽  
Numerical Studies

Abstract To investigate the application of ribbed cross-flow coolant channels with film hole effusion and the effects of the internal cooling configuration on film cooling, experimental and numerical studies are conducted on the effect of the relative position of the film holes and different orientation ribs on the film cooling performance. Three cases of the relative position of the film holes and different orientation ribs (post-rib, centered, and pre-rib) in two ribbed cross-flow channels (135° and 45° orientation ribs) are investigated. The film cooling performances are measured under three blowing ratios by the transient liquid crystal measurement technique. A RANS simulation with the realizable k-ε turbulence model and enhanced wall treatment is performed. The results show that the cooling effectiveness and the downstream heat transfer coefficient for the 135° rib are basically the same in the three position cases, and the differences between the local effectiveness average values for the three are no more than 0.04. The differences between the heat transfer coefficients are no more than 0.1. The “pre-rib” and “centered” cases are studied for the 45° rib, and the position of the structures has little effect on the film cooling performance. In the different position cases, the outlet velocity distribution of the film holes, the jet pattern and the discharge coefficient are consistent with the variation in the cross flow. The related research previously published by the authors showed that the inclination of the ribs with respect to the holes affects the film cooling performance. This study reveals that the relative positions of the ribs and holes have little effect on the film cooling performance. This paper expands and improves the study of the effect of the internal cooling configuration on film cooling and makes a significant contribution to the design and industrial application of the internal cooling channel of a turbine blade.

A CFD-Based Parametric Study on Modification of Discrete Sister Holes Location for the Film Cooling Flow

2014 ◽  
Author(s):  
Siavash Khajehhasani ◽  
Bassam Jubran
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Base Case ◽  
Spanwise Direction ◽  
Cooling Performance ◽  
Cooling Flow ◽  
Lift Off ◽  
The Individual

A numerical study on the effects of sister holes locations on film cooling performance is presented. This includes the change of the location of the individual discrete sister holes in the streamwise and spanwise directions, where each one of these directions includes 9 different locations, 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 variation of the sister holes in the streamwise direction provides similar film cooling performance as the base case for both blowing ratios of 0.5 and 1. On the other hand, the spanwise variation of the sister holes’ location has a more prominent effect on the effectiveness. In some cases, as a result of the anti-vortices generated from the sister holes and the repositioning of the sister holes in the spanwise direction, the jet lift-off effect notably decreases and more volume of coolant is distributed in the spanwise direction.

Injection Angle Influence of Secondary Holes on the Enhancement of Film Cooling Effectiveness With Horn-Shaped or Cylindrical Primary Holes

2017 ◽  
Author(s):  
Rui Zhu ◽  
Gongnan Xie ◽  
Terrence W. Simon
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Cylindrical Hole ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Injection Angle ◽  
Inclination Angles ◽  
Cooling Hole ◽  
Cylindrical Holes

Secondary holes to a main film cooling hole are used to improve film cooling performance by creating anti-kidney vortices. The effects of injection angle of the secondary holes on both film cooling effectiveness and surrounding thermal and flow fields are investigated in this numerical study. Two kinds of primary hole shapes are adopted. One is a cylindrical hole, the other is a horn-shaped hole which is designed from a cylindrical hole by expanding the hole in the transverse direction to double the hole size at the exit. Two smaller cylindrical holes, the secondary holes, are located symmetrically about the centerline and downstream of the primary hole. Three compound injection angles (α = 30°, 45° and 60°, β = 30°) of the secondary holes are analyzed while the injection angle of the primary hole is kept at 45°. Cases with various blowing ratios are computed. It is shown from the simulation that cooling effectiveness of secondary holes with a horn-shaped primary hole is better than that with a cylindrical primary hole, especially at high blowing ratios. With a cylindrical primary hole, increasing inclination angle of the secondary holes provides better cooling effectiveness because the anti-kidney vortices created by shallow secondary holes cannot counteract the kidney vortex pairs adequately, enhancing mixing of main flow and coolant. For secondary holes with a horn-shaped primary hole, large secondary hole inclination angles provide better cooling performance at low blowing ratios; but, at high blowing ratios, secondary holes with small inclination angles are more effective, as the film coverage becomes wider in the downstream area.

Experimental and Numerical Study on Effects of Turbulence Promoters on Flat Plate Film Cooling

2011 ◽  
Author(s):  
Eiji Sakai ◽  
Toshihiko Takahashi
Keyword(s):  
Flat Plate ◽  
Secondary Flow ◽  
Film Cooling ◽  
Numerical Study ◽  
Secondary Flows ◽  
Temperature Fields ◽  
Main Stream ◽  
Cooling Performance ◽  
Cooling Hole ◽  
Stream Lines

Turbulence promoters such as ribs inside turbine blade coolant channels are used to improve convective cooling but at the same time could influence external film cooling performance. The effects of rib orientation and rib position on film cooling performance are experimentally and numerically studied with a flat plate configuration in which external (main) flow and internal (secondary) flow are oriented perpendicular to each other. In the experiment, temperature fields are measured by thermo-couples varying blowing ratio at constant Reynolds number of main and secondary flows. To obtain detailed information about flow fields, Reynolds Averaged Navier Stokes (RANS) simulation and Detached Eddy Simulation (DES) are also performed using a commercial code Fluent. Temperature measured shows that rib orientation has a strong influence on film effectiveness. With forward-oriented ribs, higher film effectiveness is observed compared to the reference case without ribs. On the contrary with inverse-oriented ribs, lower film effectiveness is observed. The difference comes from the flow structure in the film cooling hole. With the forward-oriented ribs, straight stream lines are observed in the cooling hole, while with the inverse-oriented ribs, helical stream lines are observed. Due to the helical stream lines in the hole, ejection angle of the secondary flow to the main stream becomes large, resulting in so called lift-off and lower film effectiveness.

Numerical Study of Film-Cooling Performance on a Rotating Model

2009 ◽  
Vol 23 (1) ◽  
pp. 129-138 ◽  
Author(s):  
G. Q. Xu ◽  
B. Yang ◽  
Z. Tao ◽  
S. T. Ding ◽  
H. W. Wu
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Cooling Performance

Numerical Study of the Film Cooling With Discrete-Hole Arrangement on a Cut Back Squealer Blade Tip

2015 ◽  
Author(s):  
Xiang Zhang ◽  
Zhong Yang ◽  
Shuqing Tian ◽  
Haiteng Ma
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Numerical Study ◽  
Pressure Side ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Blade Tip ◽  
Cavity Floor

Detailed numerical investigations of film cooling effectiveness are conducted for the holes on the tip cavity floor and near the tip pressure side. The tested blade tip is a squealer with the trailing rim wall cut to allow the accumulated coolant in the cavity to escape and cool the trailing edge. The heat transfer coefficients on the un-cooled flat and cutback squealer blade tip are studied with numerical and experimental methods. Three dust purging holes with different diameters are arranged along the camber line, which forms the basic cooled case (PG case). Additional six tip cavity holes are arranged on cavity floor near the suction side rim (PG-TF case). Another row of angled twenty-one holes is arranged along the pressure side just below the tip based on the PG case (PG-PSF case). The coolant supply pressure ratios are controlled to be 1, 1.11, and 1.22 respectively, offering local blowing ratio from 0 to 2.5. Results show that the dust purging flow cooling performance increases with the cavity depth. Discrete holes on the cavity floor offer a well-distributed coolant, which refines the cooling effect on the cavity floor. The PG-PSF case with cooling holes on the pressure side has the best overall cooling performance with more coolant consumed, when PR ≥ 1.22. However, maintaining the same coolant mass flow the PG-TF case has the best cooling performance, and the margin between PG-TF and PG-PSF case decreases with mass flow. The moving shroud cases reveal that blade movement will cause significant negative impacts on film cooling effectiveness.

Numerical study on unsteady film cooling performance under the mainstream swing condition

2019 ◽  
Vol 33 (11) ◽  
pp. 5527-5536 ◽  
Author(s):  
Wei Zhang ◽  
Hui-ren Zhu ◽  
Quan-peng Yu ◽  
Guang-chao Li
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Cooling Performance

Numerical Analysis of Film-Cooling Performance and Optimization for a Novel Shaped Film-Cooling Hole

2012 ◽  
Author(s):  
Ki-Don Lee ◽  
Sun-Min Kim ◽  
Kwang-Yong Kim
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Density Ratio ◽  
Lateral Spreading ◽  
Diameter Ratio ◽  
The Novel ◽  
Cooling Performance ◽  
Cooling Hole ◽  
Shaped Hole ◽  
Film Cooling Holes

In the present work, a numerical study on a novel shaped film-cooling hole has been performed. The novel shaped hole is designed to enhance lateral spreading of coolant on the cooling surface. The film-cooling performance of the novel shaped hole is compared with the fan, laidback fan, and dumbbell shaped film-cooling holes at density ratio of 1.75 in the range of blowing ratio from 0.5 to 2.5. The optimization of the novel shaped hole has been carried out to increase film-cooling effectiveness with four design variables, i.e., lateral expansion of the diffuser, forward expansion angle of the hole, length to diameter ratio of the hole, and pitch to diameter ratio of the hole. To optimize the hole shape, the radial basis neural network model is constructed and sequential quadratic programming is used to find optimal point from the surrogate model. The novel shaped hole shows remarkably improved film-cooling performance in comparison with the other film-cooling holes. The novel shaped hole modified by the optimization gives enhanced performance in comparison with the reference geometry.

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