Aerothermal Investigations on Mixing Flow Field of Film Cooling With Swirling Coolant Flow

2013 ◽  
Vol 136 (5) ◽  
Author(s):  
Kenichiro Takeishi ◽  
Masaharu Komiyama ◽  
Yutaka Oda ◽  
Yuta Egawa
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Film Cooling ◽  
Vertical Direction ◽  
Coolant Flow ◽  
Bottom Surface ◽  
Cooling Effectiveness ◽  
Slant Angle ◽  
Film Cooling Effectiveness ◽  
Cooling Hole

This paper describes the experimental results of a new film cooling method that utilizes swirling coolant flow through circular and shaped film cooling holes. The experiments were conducted by using a scale-up model of a film-cooling hole installed on the bottom surface of a low-speed wind tunnel. Swirling motion of the film coolant was induced inside a hexagonal plenum using two diagonal impingement jets, which were inclined at an angle of α toward the vertical direction and installed in staggered positions. These two impingement jets generated a swirling flow inside the plenum, which entered the film-cooling hole and maintained its angular momentum until exiting the film-cooling hole. The slant angle of the impingement jets was changed to α = 0 deg, 10 deg, 20 deg, and 30 deg in the wind tunnel tests. The film cooling effectiveness on a flat wall was measured by a pressure sensitive paint (PSP) technique. In addition, the spatial distributions of the nondimensional concentration (or temperature) and flow field were measured by laser-induced fluorescence (LIF) and particle image velocimetry (PIV), respectively. In the case of a circular film-cooling hole, the penetration of the coolant jet into the mainstream was suppressed by the swirling motion of the coolant. As a result, although the coolant jet was deflected in the pitch direction, the film cooling effectiveness on the wall maintained a higher value behind the cooling hole over a long range. Additionally, the kidney vortex structure disappeared. For the shaped cooling hole, the coolant jet spread wider in the spanwise direction downstream. Thus, the pitch-averaged film cooling effectiveness downstream was 50% higher than that in the nonswirling case.

Aerothermal Investigations on Mixing Flow Field of Film Cooling With Swirling Coolant Flow

2011 ◽  
Author(s):  
K. Takeishi ◽  
M. Komiyama ◽  
Y. Oda ◽  
Y. Egawa ◽  
T. Kitamura
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Film Cooling ◽  
Vertical Direction ◽  
Coolant Flow ◽  
Bottom Surface ◽  
Cooling Effectiveness ◽  
Slant Angle ◽  
Film Cooling Effectiveness ◽  
Cooling Hole

This paper describes the experimental results of a new film cooling method blowing through circular and shaped film cooling holes with swirling coolant flow. The experiments have been conducted by using a scale-up model of a film cooling hole installed on the bottom surface of a low-speed wind tunnel. Swirling motion of film coolant was induced inside a hexagonal plenum by two slant impingement jets, which are inclined at α degree toward the vertical direction and installed in a staggered position. The two impingement jets generate swirling flows inside the plenum, and this swirling flow enters into a film cooling hole keeping the angular momentum until the exit of the film cooling hole. The slant angle of the impingement jets was changed as α = 0°, 10°, 20°, 30° in their wind tunnel tests. The film cooling effectiveness on the flat wall was measured by using pressure sensitive paint (PSP) technique. In addition, the spatial distribution of non-dimensional concentration (or temperature) and flow field were measured by laser induced fluorescence (LIF) and particle image velocimetry (PIV), respectively. In case of the circular film cooling hole, the coolant jet penetration into mainstream is suppressed by swirling motion of the coolant. As a result, though the coolant jet is deflected in the pitch direction, the film cooling effectiveness distribution on the wall keeps higher value behind the cooling hole over a long range. Additionally, kidney vortex structure disappeared. For the shaped cooling hole, the coolant jet spreads wider in spanwise direction at the downstream. Thus, the pitch averaged film cooling effectiveness at the downstream was 50% higher than that of the non-swirling case.

Film Cooling With Swirling Coolant Flow Controlled by Impingement Cooling in a Closed Cavity

2011 ◽  
Author(s):  
Kenichiro Takeishi ◽  
Yutaka Oda ◽  
Yuta Egawa ◽  
Satoshi Hada
Keyword(s):  
Wind Tunnel ◽  
Film Cooling ◽  
Vertical Direction ◽  
Coolant Flow ◽  
Swirl Number ◽  
Cooling Effectiveness ◽  
Closed Cavity ◽  
Film Cooling Effectiveness ◽  
Cooling Hole ◽  
Sublimation Method

A new film cooling concept has been developed by managing the swirled film coolant induced inside a hexagonal plenum by two slant impingement jets, which are inclined at α degree toward the vertical direction and installed in a staggered position on the plenum chamber wall. Film cooling tests have been conducted by using a circular film cooling hole model mounted on a low speed wind tunnel. Heat transfer coefficient distributions of inclined jet impingements in a closed cavity was measured by naphthalene sublimation method and the film cooling effectiveness on the surface of the wind tunnel was measured by pressure sensitive paint (PSP). It appeared from experimental results that the swirled film coolant flow deteriorated the film cooling effectiveness at low swirl number but improved it at high swirl number. To investigate the mechanism of the improved film cooling effectiveness by the swirled coolant, the spatial distribution of the film cooling effectiveness and flow field were measured by laser induced fluorescence (LIF) and particle image velocimetry (PIV), respectively. The coolant jet penetration into mainstream is suppressed by the strong swirling motion of the coolant. As a result the film cooling effectiveness distribution on the wall keeps higher value behind the cooling hole over a long range. Additionally, kidney vortex structure was disappeared at high swirl number.

Film Cooling Measurements for a Laidback Fan-Shaped Hole: Effect of Coolant Crossflow on Cooling Effectiveness and Heat Transfer

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Marc Fraas ◽  
Tobias Glasenapp ◽  
Achmed Schulz ◽  
Hans-Jörg Bauer
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Film Cooling ◽  
Gas Flow ◽  
Density Ratio ◽  
Coolant Flow ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Hole ◽  
Film Cooling Holes

Internal coolant passages of gas turbine vanes and blades have various orientations relative to the external hot gas flow. As a consequence, the inflow of film cooling holes varies as well. To further identify the influencing parameters of film cooling under varying inflow conditions, the present paper provides detailed experimental data. The generic study is performed in a novel test rig, which enables compliance with all relevant similarity parameters including density ratio. Film cooling effectiveness as well as heat transfer of a 10–10–10 deg laidback fan-shaped cooling hole is discussed. Data are processed and presented over 50 hole diameters downstream of the cooling hole exit. First, the parallel coolant flow setup is discussed. Subsequently, it is compared to a perpendicular coolant flow setup at a moderate coolant channel Reynolds number. For the perpendicular coolant flow, asymmetric flow separation in the diffuser occurs and leads to a reduction of film cooling effectiveness. For a higher coolant channel Reynolds number and perpendicular coolant flow, asymmetry increases and cooling effectiveness is further decreased. An increase in blowing ratio does not lead to a significant increase in cooling effectiveness. For all cases investigated, heat transfer augmentation due to film cooling is observed. Heat transfer is highest in the near-hole region and decreases further downstream. Results prove that coolant flow orientation has a severe impact on both parameters.

Film-Cooled Turbine Endwall in a Transonic Flow Field: Part I—Aerodynamic Measurements

2001 ◽  
Vol 123 (4) ◽  
pp. 709-719 ◽  
Author(s):  
Friedrich Kost ◽  
Martin Nicklas
Keyword(s):  
Flow Field ◽  
Transonic Flow ◽  
Film Cooling ◽  
Coolant Flow ◽  
Pressure Probe ◽  
Thermal Methods ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Oil Flow ◽  
Oil Flow Visualization

Thermodynamic and aerodynamic measurements were carried out in a linear turbine cascade with transonic flow field. Heat transfer and adiabatic film-cooling effectiveness resulting from the interaction of the flow field and the ejected coolant at the endwall were measured and will be discussed in two parts. The investigations were performed in the Windtunnel for Straight Cascades (EGG) at DLR, Go¨ttingen. The film-cooled NGV endwall was operated at representative dimensionless engine conditions of Mach and Reynolds number Ma2is=1.0 and Re2=850,000 respectively. Part I of the investigation discusses the aerodynamic measurements. Detailed aerodynamic measurements were carried out in the vicinity of a turbine stator endwall using conventional pressure measurements and a Laser-2-Focus (L2F) device. The L2F served as a velocimeter measuring 2D-velocity vectors and turbulence quantities and as a tool to determine the concentration of coolant ejected through a slot and through holes at the endwall. Pressure distribution measurements provided information on the endwall pressure field and its variation with coolant flow rate. Pressure probe measurements delivered cascade performance data. Oil flow visualization and laser velocimetry gave a picture of the near endwall flow field and its interference with the coolant. A strikingly strong interaction of coolant air and secondary flow field could be identified. The measurement of coolant concentration downstream of the ejection locations provided a detailed picture of the coolant flow convection and its mixing with the main flow. The relative coolant concentration in the flow field is directly comparable to the adiabatic film-cooling effectiveness measured by thermal methods at the wall.

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.

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.

Experimental Investigations on Aero-Thermal Interaction of Film Cooling Air Ejected From Multiple Shallow Angle Cooling Holes: Effect of Freestream Turbulence

2013 ◽  
Author(s):  
Kamil Abdullah ◽  
Ken-ichi Funazaki
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Lateral Spreading ◽  
Test Model ◽  
Thermal Interaction ◽  
Freestream Turbulence ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Test Models ◽  
Cooling Hole

The objective of the present study is to investigate the aero-thermal interaction of the secondary air injected from multiple shallow angled film cooling holes. The focus is on the influence of freestream turbulence on the film cooling effectiveness and secondary flow field. For the experiments, infrared thermography and Laser Doppler Velocimetry (LDV) were employed. The experiments were conducted at a Reynolds number based on the hole diameter, ReD = 6200 at blowing ratio, BR = 1.0 and 2.0. Two flat plate test models; TMA and TMG, have been considered, which involved twenty cylindrical holes constituting a matrix composed of four rows with five holes in each row. The cooling holes for both test models were inclined at 20° in the streamwise direction with the lateral pitch, Pz = 6D for TMA and 3D for TMG. Two different freestream turbulence levels have been considered for both the aerodynamic and thermal investigations. The results of LDV show two distinct dynamics for each test model which influence the flow field differently. Consequently, the thermal field produced a distinctive film cooling effectiveness distribution of each test model. Higher freestream turbulence level enhances the mixing in the vicinity of the vortical structure thus deterring the film cooling effectiveness just downstream of the cooling hole but aids to lateral spreading of the coolant further downstream of the cooling hole, providing greater film effectiveness coverage.

Jets in a Crossflow: Effects of Geometry and Blowing Ratio

1999 ◽  
Vol 121 (2) ◽  
pp. 373-378 ◽  
Author(s):  
M. J. Findlay ◽  
M. Salcudean ◽  
I. S. Gartshore
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Film Cooling ◽  
Density Ratio ◽  
Mean Velocity ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Flow Field Characteristics ◽  
Square Jets ◽  
Inlet Conditions

The flow field characteristics of three different geometries of square jets in a crossflow at various blowing ratios are examined. The geometries considered are: perpendicular, streamwise-inclined, and spanwise-inclined jets. The inclined jets are at a 30 deg angle to the wind tunnel floor. Mean velocity and turbulence measurements along with film cooling effectiveness and scalar transport data were obtained. Jet-to-crossflow blowing ratios of 1.5, 1.0 and 0.5 are used with a density ratio of 1. It is shown that the flow field at the jet exit is strongly influenced by the crossflow as well as by the inlet conditions at the entrance to the jet orifice. The strong streamline curvature which is present in the perpendicular and spanwise injection cases appears to result in the greatest turbulence anisotropy. The film cooling effectiveness is best at the lowest blowing ratios as the jet is deflected strongly towards the floor of the wind tunnel, although the improvement is more significant for the streamwise injection case.

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.

Film-Cooled Turbine Endwall in a Transonic Flow Field: Part I — Aerodynamic Measurements

2001 ◽  
Author(s):  
Friedrich Kost ◽  
Martin Nicklas
Keyword(s):  
Flow Field ◽  
Transonic Flow ◽  
Film Cooling ◽  
Coolant Flow ◽  
Pressure Probe ◽  
Thermal Methods ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Oil Flow ◽  
Oil Flow Visualization

Thermodynamic and aerodynamic measurements were carried out in a linear turbine cascade with transonic flow field. Heat transfer and adiabatic film-cooling effectiveness resulting from the interaction of the flow field and the ejected coolant at the endwall were measured and will be discussed in two parts. The investigations were performed in the Windtunnel for Straight Cascades (EGG) at DLR, Göttingen. The film-cooled NGV endwall was operated at representative dimensionless engine conditions of Mach and Reynolds number Ma2is=1.0 and Re2=850,000 respectively. Part I of the investigation discusses the aerodynamic measurements. Detailed aerodynamic measurements were carried out in the vicinity of a turbine stator endwall using conventional pressure measurements and a Laser-2-Focus (L2F) device. The L2F served as a velocimeter measuring 2D-velocity vectors and turbulence quantities and as a tool to determine the concentration of coolant ejected through a slot and through holes at the endwall. Pressure distribution measurements provided information on the endwall pressure field and its variation with coolant flow rate. Pressure probe measurements delivered cascade performance data. Oil flow visualization and laser velocimetry gave a picture of the near endwall flow field and its interference with the coolant. A strikingly strong interaction of coolant air and secondary flow field could be identified. The measurement of coolant concentration downstream of the ejection locations provided a detailed picture of the coolant flow convection and its mixing with the main flow. The relative coolant concentration in the flow field is directly comparable to the adiabatic film-cooling effectiveness measured by thermal methods at the wall.

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