COMPUTATIONAL INVESTIGATION OF CURVATURE EFFECTS ON JET IMPINGEMENT HEAT TRANSFER AT INTERNALLY COOLED TURBINE VANE LEADING EDGE REGIONS

2020 ◽  
Vol 51 (4) ◽  
pp. 333-357 ◽  
Author(s):  
Lei Luo ◽  
Yifeng Zhang ◽  
Bengt Sunden ◽  
Dandan Qiu ◽  
Songtao Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Leading Edge ◽  
Jet Impingement ◽  
Computational Investigation ◽  
Curvature Effects ◽  
Impingement Heat Transfer ◽  
Turbine Vane ◽  
Internally Cooled

scholarly journals Experimental study of curvature effects on jet impingement heat transfer on concave surfaces

2017 ◽  
Vol 30 (2) ◽  
pp. 586-594 ◽  
Author(s):  
Ying Zhou ◽  
Guiping Lin ◽  
Xueqin Bu ◽  
Lizhan Bai ◽  
Dongsheng Wen
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Jet Impingement ◽  
Curvature Effects ◽  
Impingement Heat Transfer

scholarly journals Micro scale jet impingement cooling and its efficacy on turbine vanes : a numerical study

2021 ◽  
Author(s):  
Santhiya Jayaraman
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Leading Edge ◽  
Jet Impingement ◽  
3D Analysis ◽  
Transfer Rates ◽  
Impingement Cooling ◽  
Micro Scale ◽  
Turbine Vane ◽  
Nozzle Configuration

A numerical analysis of effectiveness of micro-jet impingement cooling on leading edge of a turbine vane is presented. An axisymmetric single round jet was assessed for its ability and consistency as a preliminary study including the investigation of parameters influencing the heat transfer distribution. The analysis revealed that an increase in Nusselt number was attributed to increase in Reynolds number, decrease in jet diameter and H/D < 3. Significant improvement in heat transfer was observed for tapering nozzle configuration. The study was then further expanded to 3D analysis of leading edge cooling of turbine vane. Effect of nozzle diameter to micro-scale was studied, which showed 65% enhancement in the heat transfer rates.

Parametric Study on Micro-Roughness Shapes for Enhanced Jet Impingement Heat Transfer

2020 ◽  
Author(s):  
Ramaswamy Devakottai ◽  
Srivatsan Madhavan ◽  
Prashant Singh ◽  
Srinath V. Ekkad
Keyword(s):  
Heat Transfer ◽  
Turbine Blades ◽  
Leading Edge ◽  
Jet Impingement ◽  
Diameter Ratio ◽  
External Diameter ◽  
Concentric Cylinder ◽  
Pin Fin ◽  
Plate Spacing ◽  
Impingement Heat Transfer

Abstract Development of efficient cooling technologies are imperative to support the constant push for higher turbine inlet temperatures to achieve increased overall turbine efficiency. High-pressure stage turbine blades are subjected to hostile environment involving high temperature turbulent flow exiting from the combustor section. The blade leading edge is subjected to flow stagnation and hence requires special attention in terms of both, internal and external cooling. This study is focused on improving the internal side heat transfer coefficient by installing novel micro-roughness elements on the target wall. The study is based on Singh, Prashant, et al. “Effect of micro-roughness shapes on jet impingement heat transfer and fin-effectiveness.” International Journal of Heat and Mass Transfer 132 (2019): 80–95, where different micro-roughness shapes were investigated experimentally and numerically. The authors proposed that the novel concentric-cylinder shaped roughened geometry exhibited highest fin-effectiveness. Present study reports the effect of three micro-roughness shapes, viz. cylindrical, cubic and concentric cylinder. Conjugate heat transfer study was performed, and the heat transfer performance was reported in the form of local Nusselt number and globally averaged fin-effectiveness. An array jet configuration of 5 × 5 jets with a jet-to-jet spacing of X/Djet = Y/Djet = 3 and jet-to-target plate spacing of Z/Djet = 1 was maintained for jet-diameter based Reynolds number (ReDjet) ranging from 3,000 to 12,000. Investigation on the effect of pin-fin shapes shows that the concentric-shaped micro pin-fin element had the highest fin-effectiveness of 2.45 at ReDjet = 12,000. Further, pin-fin optimization studies were performed for the concentric cylinder pin-fin shape, where the effect of pin-fin height and the effect of internal to external diameter ratio was studied. The pin-fin effectiveness increased with increase in height and diameter ratio, and a maximum fin effectiveness was observed for maximum pin-fin height.

Impingement Heat Transfer on a Cylindrical, Concave Surface With Varying Jet Geometries

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
C. Neil Jordan ◽  
Lesley M. Wright ◽  
Daniel C. Crites
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Leading Edge ◽  
Jet Impingement ◽  
Reynolds Numbers ◽  
Hydraulic Diameter ◽  
Hole Shape ◽  
Impingement Heat Transfer ◽  
Cylindrical Holes

Jet impingement is often employed within the leading edge of turbine airfoils to combat the heat loads incurred within this region. This experimental investigation employs a transient liquid crystal technique to obtain detailed Nusselt number distributions on a concave, cylindrical surface that models the leading edge of a turbine airfoil. The effect of hole shape and differing hole inlet and exit conditions are investigated. Two hole shapes are studied: cylindrical and racetrack-shaped holes; for each hole shape, the hydraulic diameter and mass flow rate into the array of jets is conserved. As a result, the jet's Reynolds number varies between the two jet arrays. Reynolds numbers of 13,600, 27,200, and 40,700 are investigated for the cylindrical holes, and Reynolds numbers of 11,500, 23,000, and 34,600 are investigated for the racetrack holes. Three inlet and exit conditions are investigated for each hole shape: a square edged, a partially filleted, and a fully filleted hole. The ratio of the fillet radius to hole hydraulic diameter is set at 0.25 and 0.667 for the partially and fully filleted holes, respectively, while all other geometrical features remain constant. Results show the Nusselt number is directly related to the Reynolds number for both cylindrical and racetrack-shaped holes. The racetrack holes are shown to provide enhanced heat transfer compared to the cylindrical holes. The degree of filleting at the inlet and outlet of the holes affects whether the heat transfer on the leading edge model is further enhanced or degraded.

scholarly journals Micro scale jet impingement cooling and its efficacy on turbine vanes : a numerical study

2021 ◽  
Author(s):  
Santhiya Jayaraman
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Leading Edge ◽  
Jet Impingement ◽  
3D Analysis ◽  
Transfer Rates ◽  
Impingement Cooling ◽  
Micro Scale ◽  
Turbine Vane ◽  
Nozzle Configuration

A numerical analysis of effectiveness of micro-jet impingement cooling on leading edge of a turbine vane is presented. An axisymmetric single round jet was assessed for its ability and consistency as a preliminary study including the investigation of parameters influencing the heat transfer distribution. The analysis revealed that an increase in Nusselt number was attributed to increase in Reynolds number, decrease in jet diameter and H/D < 3. Significant improvement in heat transfer was observed for tapering nozzle configuration. The study was then further expanded to 3D analysis of leading edge cooling of turbine vane. Effect of nozzle diameter to micro-scale was studied, which showed 65% enhancement in the heat transfer rates.

Impingement Heat Transfer Enhancement on a Cylindrical, Leading Edge Model With Varying Jet Temperatures

2012 ◽  
Author(s):  
Evan L. Martin ◽  
Lesley M. Wright ◽  
Daniel C. Crites
Keyword(s):  
Heat Transfer ◽  
Experimental Technique ◽  
Leading Edge ◽  
Jet Impingement ◽  
Target Surface ◽  
Large Temperature ◽  
Transfer Coefficients ◽  
Stagnation Region ◽  
Heat Transfer Coefficients ◽  
Impingement Heat Transfer

Stagnation region heat transfer coefficients are obtained from jet impingement onto a concave surface in this experimental investigation. A single row of round jets impinge on the cylindrical target surface to replicate leading edge cooling in a gas turbine airfoil. A modified, transient lumped capacitance experimental technique was developed (and validated) to obtain stagnation region Nusselt numbers with jet-to-target surface temperature differences ranging from 60°F (33.3°C) to 400°F (222.2°C). In addition to varying jet temperatures, the jet Reynolds number (5000–20000), jet-to-jet spacing (s/d = 2–8), jet-to-target surface spacing (ℓ/d = 2–8), and impingement surface diameter-to-jet diameter (D/d = 3.6, 5.5) were independently varied. This parametric investigation has served to develop and validate a new experimental technique which can be used for investigations involving large temperature differences between the surface and fluid. Furthermore, the study has broadened the range of existing correlations currently used to predict heat transfer coefficients for leading edge, jet impingement.

Impingement Heat Transfer Enhancement on a Cylindrical, Leading Edge Model With Varying Jet Temperatures

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Evan L. Martin ◽  
Lesley M. Wright ◽  
Daniel C. Crites
Keyword(s):  
Heat Transfer ◽  
Experimental Technique ◽  
Leading Edge ◽  
Jet Impingement ◽  
Target Surface ◽  
Large Temperature ◽  
Transfer Coefficients ◽  
Stagnation Region ◽  
Heat Transfer Coefficients ◽  
Impingement Heat Transfer

Stagnation region heat transfer coefficients are obtained from jet impingement onto a concave surface in this experimental investigation. A single row of round jets impinge on the cylindrical target surface to replicate leading edge cooling in a gas turbine airfoil. A modified, transient lumped capacitance experimental technique was developed (and validated) to obtain stagnation region Nusselt numbers with jet-to-target surface temperature differences ranging from 60 °F (33.3 °C) to 400 °F (222.2 °C). In addition to varying jet temperatures, the jet Reynolds number (5000–20,000), jet-to-jet spacing (s/d = 2–8), jet-to-target surface spacing (ℓ/d = 2–8), and impingement surface diameter-to-jet diameter (D/d = 3.6, 5.5) were independently varied. This parametric investigation has served to develop and validate a new experimental technique, which can be used for investigations involving large temperature differences between the surface and fluid. Furthermore, the study has broadened the range of existing correlations currently used to predict heat transfer coefficients for leading edge jet impingement.

Experimental Racetrack Shaped Jet Impingement on a Roughened Leading-Edge Wall With Film Holes

2002 ◽  
Author(s):  
M. E. Taslim ◽  
Y. Pan ◽  
K. Bakhtari
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Leading Edge ◽  
Jet Impingement ◽  
Target Surface ◽  
Cross Sectional ◽  
Impingement Heat Transfer ◽  
Circular Jets ◽  
Edge Surface

Compatible with the external contour of the turbine airfoils at their leading edge, the leading-edge cooling cavities have a complex cross-sectional shape. To enhance the heat transfer coefficient on the leading-edge wall of these cavities, the cooling flow in some designs enters the leading-edge cavity from the adjacent cavity through a series of crossover holes on the partition wall between the two cavities. The crossover jets then impinge on the concave leading-edge wall and exit through the showerhead film holes, gill film holes on the pressure and suction sides, and, in some cases, form a crossflow in the leading-edge cavity and move toward the airfoil tip. The main objective of this investigation was to study the effects that racetrack crossover jets, in the presence of film holes on the target surface, have on the impingement heat transfer coefficient. Available data in open literature are mostly for impingement on a flat smooth surface with no representation of the film holes. This investigation covered new features in airfoil leading-edge cooling concept such as impingement with racetrack shaped holes on a roughened target surface with a row of holes representing the leading-edge showerhead film holes. Results of the circular crossover jets impinging on these leading-edge surface geometries with and without showerhead holes were reported by these authors previously. In this paper, however, the experimental results are presented for the impingement of racetrack-shaped crossover jets on a concave surface with showerhead film holes. The investigated target surface geometries were : (1) a smooth wall, (2) a wall roughened with big conical bumps, (3) a wall roughened with smaller conical bumps and (4) a wall roughened with tapered radial ribs. The tests were run for a range of flow arrangements and jet Reynolds numbers and the results were compared with those of round crossover jets. The major conclusions of this study are: (a) for a given jet Reynolds number, the racetrack crossover jets produce a higher impingement heat transfer coefficient than the circular jets, (b) the overall heat transfer performance of 0° racetrack crossover jets is superior to that of 45° racetrack crossover jets and (c) there is a heat transfer enhancement benefit in roughening the target surface. With the presence of showerhead holes, the enhancement is due to both the impingement heat transfer coefficient and the heat transfer area increase.

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