Double-Row Discrete-Hole Cooling: an Experimental and Numerical Study

1980 ◽  
Vol 102 (2) ◽  
pp. 498-503 ◽  
Author(s):  
G. Bergeles ◽  
A. D. Gosman ◽  
B. E. Launder
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Free Stream ◽  
Numerical Study ◽  
Transport Coefficients ◽  
Three Dimensional ◽  
Double Row ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Row

Double-row discrete-hole cooling arrangements offer several advantages over single-row systems yet the detailed cooling mechanism is less completely understood than for the single-row. This is partly because there have been fewer studies of this geometry and partly because the flow structure is more complex. The present paper presents detailed flow-field and concentration measurements around the injection holes for double-row injection on a flat plate at 30 deg to the mainstream. The experiments span values of the blowing injection mass velocities from 0.25 to 1.0 times the free stream mass velocity and for two boundary layer thicknesses just upstream of the injection. In contrast to single-row injection the cooling effectiveness rise monotonically with M over the range studied. Computer simulation of these flows and similar experiments of [7] has been made using a three-dimensional finite-difference code that embodies a semi-elliptic treatment of the flow field in the neighborhood of the injection holes in conjunction with a two-equation turbulence model with non-isotropic effective transport coefficients. It emerged from the calculations, that, for injection velocities up to 50 percent of the free stream value, levels of film-cooling effectiveness are extremely well predicted beyond about 10 diameters behind the leading row of holes. Around the holes themselves, however, there are certain discrepancies which become more serious as the injection level is raised.

Flow Dynamics and Film Cooling Effectiveness on a Non-Axisymmetric Contour Endwall in a Two-Dimensional Cascade Passage

2009 ◽  
Author(s):  
Gazi I. Mahmood ◽  
Ross Gustafson ◽  
Sumanta Acharya
Keyword(s):  
Temperature Field ◽  
Flow Field ◽  
Film Cooling ◽  
Free Stream ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
Blowing Ratio

The measured flow field and temperature field near a three-dimensional asymmetric contour endwall employed in a linear blade cascade are presented with and without film-cooling flow on the endwall. Flow field temperature and Nusselt number distributions along the asymmetric endwall with wall heating and no film-cooling flow are also reported to show local high heat transfer region on the endwall and justify the locations of the coolant holes. Adiabatic film-cooling effectiveness along the endwall is then measured to indicate the local effects of the coolant jets. The near endwall flow field and temperature field provide the coolant flow behavior and the interaction of coolant jets with the boundary layer flow. Thus, the local film-cooling effectiveness can be explained with the coolant jet trajectories. The measurements are obtained at the Reynolds number of 2.30×105 based on blade actual chord and inlet velocity, coolant-to-free stream temperature ratio of 0.93, and coolant-to-free stream density ratio of 1.06. The cascade employs the hub side blade section and passage geometry of the first stage rotor of GE-E3 turbine engine. The contour endwall profile is employed on the bottom endwall only in the cascade. The blowing ratio of the film-cooling flow varies from 1.0 to 2.4 from 71 discrete cylindrical holes located in the contour endwall. The three-dimensional profile of the endwall varies in height in both the pitchwise and axial directions. The flow field is quantified with the streamwise vorticity and turbulent intensity, pitchwise static pressure difference, flow yaw angle, and pitchwise velocity. Both the flow field and temperature data indicate that the coolant jets cover more distance in the pitchwise and axial direction in the passage as the blowing ratio increases. Thus, the local and average film-cooling effectiveness increase with the blowing ratio.

scholarly journals Experimental Study Of Short Hole Film-Cooling

2021 ◽  
Author(s):  
Mohammed A. Gandhi
Keyword(s):  
Experimental Study ◽  
Wind Tunnel ◽  
Film Cooling ◽  
Double Row ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
Blowing Ratio ◽  
Lift Off ◽  
Low Speed Wind Tunnel

An experimental study was conducted to investigate the film cooling effectiveness of a few configurations of short injection holes: single row, double row and both of the preceding cases with an upstream ramp placed at two different locations. In order to perform the above study, a wind-tunnel facility was assembled to facilitate in the successful culmination of the experiments. The focus of the study was to determine the cooling provided by the short injection holes at a variety of blowing ratios and whether adding an extra row of holes, upstream of the first row would make a difference. For the second part, a ramp was placed upstream of the single and double row configuration to help improve cooling . All of the experiments were performed in a low speed wind-tunnel with a mainstream velocity of 8 m/s and a turbulence insity of 3.3%. Higher blowing ratios were ineffective in improving film-cooling effectiveness due to jet lift-off. Two rows of holes increased the cooling effectiveness by 200%, when compared to single row configurations at the same blowing ratio without ramps. Upstream ramps provided significant improvement in the near hole region of the injection holes.

scholarly journals Experimental Study Of Short Hole Film-Cooling

2021 ◽  
Author(s):  
Mohammed A. Gandhi
Keyword(s):  
Experimental Study ◽  
Wind Tunnel ◽  
Film Cooling ◽  
Double Row ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
Blowing Ratio ◽  
Lift Off ◽  
Low Speed Wind Tunnel

An experimental study was conducted to investigate the film cooling effectiveness of a few configurations of short injection holes: single row, double row and both of the preceding cases with an upstream ramp placed at two different locations. In order to perform the above study, a wind-tunnel facility was assembled to facilitate in the successful culmination of the experiments. The focus of the study was to determine the cooling provided by the short injection holes at a variety of blowing ratios and whether adding an extra row of holes, upstream of the first row would make a difference. For the second part, a ramp was placed upstream of the single and double row configuration to help improve cooling . All of the experiments were performed in a low speed wind-tunnel with a mainstream velocity of 8 m/s and a turbulence insity of 3.3%. Higher blowing ratios were ineffective in improving film-cooling effectiveness due to jet lift-off. Two rows of holes increased the cooling effectiveness by 200%, when compared to single row configurations at the same blowing ratio without ramps. Upstream ramps provided significant improvement in the near hole region of the injection holes.

Numerical Study on the Influence of Hole Shape on Film Cooling Effectiveness

2013 ◽  
Vol 716 ◽  
pp. 699-704 ◽  
Author(s):  
Ping Dai ◽  
Nai Yun Yu
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Three Dimensional ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Cylindrical Holes ◽  
Shaped Hole ◽  
Volume Method ◽  
Lateral Area

Effects of hole shapes on film cooling effectiveness downstream of one row of film holes at the blade were investigated using a three-dimensional finite volume method and multi-block technique. The present study also received velocity vectors about different hole shapes. The hole geometries studied include standard cylindrical hole and forward diffused shaped hole and converging slot-hole. It was found that the film cooling effectiveness of cylindrical holes obviously declined along with increasing the blowing ratio. Results of the shaped holes configuration present a marked improvement, with a high effectiveness at the lateral area between adjacent holes and effectiveness of the converging slot-hole was superior to other holes in various blowing ratios. The film cooling effectiveness realized by the slot-holes compared to the cylindrical and forward diffused shaped holes was more excelled at downstream of the intersection of the two slot-holes. The converging slot-hole and forward diffused shaped hole can reduce the vortex intensity, and then enhance the film cooling effectiveness.

Experimental and Numerical Investigation of Flow Field and Downstream Surface Temperatures of Cylindrical and Diffuser Shaped Film Cooling Holes

2011 ◽  
Author(s):  
Tilman auf dem Kampe ◽  
Stefan Vo¨lker ◽  
Torsten Sa¨mel ◽  
Christian Heneka ◽  
Helge Ladisch ◽  
...  
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Numerical Study ◽  
Density Ratio ◽  
Quantitative Agreement ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Flow Parameters ◽  
Contour Plots ◽  
Cooling Hole

An experimental and numerical study of the flow field and the downstream film cooling performance of cylindrical and diffuser shaped cooling holes is presented. The measurements were conducted on a flat plate with a single cooling hole with coolant ejected from a plenum. The flow field was investigated by means of 3D-PIV as well as 3D-LDV measurements, the downstream film cooling effectiveness by means of infrared thermography. Cylindrical and diffuser holes without lateral inclination have been examined, varying blowing ratio and density ratio as well as freestream turbulence levels. 3D-CFD simulations have been performed and validated along with the experimental efforts. The results, presented in terms of contour plots of the three normalized velocity components as well as adiabatic film cooling effectiveness, clearly show the flow structure of the film cooling jets and the differences brought about by the variation of hole geometry and flow parameters. The quantitative agreement between experiment and CFD was reasonable, with better agreement for cylindrical holes than for diffuser holes.

scholarly journals Utilization of the Transient Liquid Crystal Technique for Film Cooling Effectiveness and Heat Transfer Investigations on a Flat Plate and a Turbine Airfoil

1997 ◽  
Author(s):  
U. Drost ◽  
A. Bölcs ◽  
A. Hoffs
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Flat Plate ◽  
Film Cooling ◽  
Coolant Temperature ◽  
Double Row ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
Transient Liquid Crystal Technique

The transient liquid crystal technique has been used to measure film cooling effectiveness and heat transfer on a flat plate in a free jet, and a turbine airfoil in a linear cascade. A multiple-test regression method has been developed for the data reduction, considering a transient coolant temperature evolution. Flat plate film cooling was investigated for a single row of 35° inclined holes at Mach numbers of 0.3 and 0.5, and two turbulence intensities. Downstream of injection heat transfer was increased in-between the holes due to enhanced turbulence caused by the shearing of the coolant and the mainstream. At higher turbulence intensity the range of blowing ratios was broader as lift-off was delayed. Rim cooling measurements on the airfoil were conducted at engine-representative flow conditions. A maximum effectiveness of 0.3 behind injection was observed on the suction side, with slightly higher values for a double row in comparison to a single row configuration. Due to a high coolant momentum, the effectiveness on the pressure side was very low at about 0.05 for a single row configuration.

Numerical Study on Film Cooling Effectiveness from Converging Slot-Hole

2013 ◽  
Vol 740 ◽  
pp. 836-841
Author(s):  
Ping Dai ◽  
Nai Yun Yu
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Three Dimensional ◽  
Lateral Spreading ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Vortex Pairs ◽  
Hole Geometry ◽  
Volume Method

Film cooling effectiveness downstream and spanwise distribution of one row of converging slot-holes at the blade were investigated using a three-dimensional finite volume method and multi-block technique at the blowing ratio ranging from 0.5 to 2.0. Previous successful application of a two-layer turbulence model to cylindrical is extended to predict film cooling for the converging slot-hole geometry. Also, the influence of jet angle on film cooling effectiveness from converging slot-holes at the blade was studied. The results showed that the centerline effectiveness of converging slot-hole was going to be increased along with blowing ratio increasing. It was also shown that the uniform lateral spreading of the effectiveness with an enhancement of the intersection of the two slot-holes. It was found that cooling effectiveness for 25° was superior to other jet angle for any blowing ratios. Furthermore, the improvement realized by the small jet angle compared to the other jet angle holes was more important at the higher blowing ratio than it was at the lower one. Cooling effectiveness of 45° and 60° holes was declining along downstream of the holes, but it was improving over again at somewhere from downstream and then it was continuing decline. Cooling effectiveness of 60° holes presented a marked improvement compared to 45° holes at beyond downstream of the holes. Counter rotating vortex pairs at the exit of big jet angle holes were obvious and strong, but these vortexes have been weakened at the exit of small jet angle holes and results in a better coolant protection than that of the big jet angle holes.

Numerical Study on Cooling Characteristics of Double-Row Cylindrical Holes on Upstream Endwall

2019 ◽  
Author(s):  
Ding Luo ◽  
Ruishan Lu ◽  
Jiang Lei ◽  
Lesley M. Wright
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Leading Edge ◽  
Computational Domain ◽  
Double Row ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Horseshoe Vortices ◽  
Cylindrical Holes ◽  
Endwall Film Cooling

Abstract In this paper film-cooling effectiveness of two rows of cylindrical holes located on the endwall upstream of a vane is investigated numerically. Five different cooling schemes, including three schemes of double rows cylindrical holes (β = −45°, 0°, 45°), and two schemes of Double-jet film cooling (DJFC) holes (β = −45°, 45° and β = 45°, −45°), are arranged on the endwall at four blowing ratios (M = 0.5, 1.0, 1.5, 2.0). Both primary effect (on downstream endwall) and secondary effect (on pressure and suction surfaces) of the endwall film cooling are considered. ICEM is used to mesh the computational domain, and simulation is carried out by ANSYS 14.0. The result shows that cooling jets with compound angles can effectively suppress lifting-off and increase film-cooling effectiveness. In addition, at low blowing ratios, it is difficult for jets no matter what directions to cool the neighborhood of the leading edge and the pressure side due to the effect of horseshoe vortices. However, passage vortices have different effects on the cooling jets with different compound angles which will result in different film coverage on both endwall and airfoil.

Numerical Study on Film-Cooling Effectiveness for Various Film-Cooling Hole Schemes

2011 ◽  
Author(s):  
Sun-min Kim ◽  
Ki-Don Lee ◽  
Kwang-Yong Kim
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Cooling Hole ◽  
Influential Parameters

Film-cooling has been widely used as the important alternative to protect the turbine blade. Since the film-cooling hole geometry is one of the most influential parameters for film-cooling performance, various film-cooling hole schemes have been developed to increase cooling performance for the past few decades. In the present work, numerical analysis has been performed to investigate and to compare the film-cooling performance of various film-cooling hole schemes such as fan-shaped, crescent, louver, and dumbbell holes. For analyzes of the turbulent flow and film-cooling, three-dimensional Reynolds-averaged Navier-Stokes analysis has been performed with shear stress transport turbulence model. The validation of numerical results has been performed in comparison with experimental data. The flow characteristics and film-cooling performance for each hole shape have been investigated and evaluated in terms of local- and averaged film-cooling effectivenesses.

Experimental and Numerical Investigation of Flow Field and Downstream Surface Temperatures of Cylindrical and Diffuser Shaped Film Cooling Holes1

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Tilman auf dem Kampe ◽  
Stefan Völker ◽  
Torsten Sämel ◽  
Christian Heneka ◽  
Helge Ladisch ◽  
...  
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Numerical Study ◽  
Density Ratio ◽  
Quantitative Agreement ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Flow Parameters ◽  
Contour Plots ◽  
Cooling Hole

An experimental and numerical study of the flow field and the downstream film cooling performance of cylindrical and diffuser shaped cooling holes is presented. The measurements were conducted on a flat plate with a single cooling hole with coolant ejected from a plenum. The flow field was investigated by means of 3D-PIV as well as 3D-LDV measurements, the downstream film cooling effectiveness by means of infrared thermography. Cylindrical and diffuser holes without lateral inclination have been examined, varying blowing ratio and density ratio as well as freestream turbulence levels. 3D-CFD simulations have been performed and validated along with the experimental efforts. The results, presented in terms of contour plots of the three normalized velocity components as well as adiabatic film cooling effectiveness, clearly show the flow structure of the film cooling jets and the differences brought about by the variation of hole geometry and flow parameters. The quantitative agreement between experiment and CFD was reasonable, with better agreement for cylindrical holes than for diffuser holes.

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