Film Cooling of Compound Angle Upstream Sister Holes

2019 ◽  
Author(s):  
Sana Abd Alsalam ◽  
Bassam Jubran
Keyword(s):  
Film Cooling ◽  
Turbulence Modeling ◽  
Stokes Equations ◽  
Density Ratio ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Simple Strategy ◽  
Compound Angle

Abstract This study introduces a novel and simple strategy; compound angle upstream sister holes (CAUSH) to increase film cooling performance of the cylindrical hole by combining two techniques: Sister holes; (two small round holes placed upstream the primary hole) and compound angle hole. Whereas the upstream sister holes were injected at several compound angles β = 0°, 45°, 75°, and 90°, while the main hole was injected to the streamwise direction at 35° on a flat plate. FLUENT-ANSYS code was used to perform the simulation by solving the 3D Reynolds Averaged Navier-Stokes Equations. The capability of three types of k-ε turbulence modeling combined with the enhanced wall treatment is investigated to predict the film cooling performance of sister holes. A detailed computational analysis of the cooling performance of the (CAUSH) and the flow field was done at a density ratio equal to two (D.R = 2) and four blowing ratios M = 0.25, 0.5, 1.0 and 1.5 to predict the centerline and laterally averaged film cooling performance. The centerline effectiveness results showed that the highest cooling performance from the examined (CAUSH) was obtained at β = 0°, 45°, and 90° for low and high blowing ratio, the highest laterally averaged film cooling performance was captured at β = 0° and 90° for all tested blowing ratios. Also, the results indicated that the upstream sister hole with 90° compound angle holes has the best overall film cooling effectiveness while the worst performance is attained at β = 75°.

Improvement in Film Cooling Effectiveness Using Single and Double Rows of Holes With Adverse Compound Angle Orientations

2018 ◽  
Vol 11 (2) ◽  
Author(s):  
E. Kannan ◽  
Seralathan Sivamani ◽  
D. G. Roychowdhury ◽  
T. Micha Premkumar ◽  
V. Hariram
Keyword(s):  
Film Cooling ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Cylindrical Hole ◽  
Navier Stokes ◽  
Cooling Effectiveness ◽  
Navier Stokes Equations ◽  
Film Cooling Effectiveness ◽  
Turbine Blade Cooling ◽  
Compound Angle

Abstract Three-dimensional Reynolds-averaged Navier–Stokes equations with shear stress transport turbulence model are used to analyze the film cooling effectiveness on a flat plate having single row of film hole involving cylindrical hole (CH) and laidback hole (LBH). The CH and LBH are inclined at 35 deg to the surface with a compound angle (β) orientation ranging from favorable to adverse inclination (i.e., β = 0–180 deg) and examined at high and low blowing ratios (M = 1.25 and 0.60). CH with an adverse compound angle of 135 deg gives the highest area-averaged film cooling effectiveness in comparison with LBH configuration. Also, CH β = 135 deg film hole shows a higher lateral coolant spread. Later, double jet film cooling (DJFC) concept is studied for this CH. In all the cases, the first hole compound angle is fixed as 135 deg, and the second hole angle is varied from 135 deg to 315 deg. At high blowing ratio, the dual jet cylindrical hole (DJCH) with β = 135 deg, 315 deg gives a higher area-averaged film cooling effectiveness by around 66.50% compared to baseline CH β = 0 deg. On comparing all CH, LBH, and DJCH cases, the highest area-averaged film cooling effectiveness is obtained by CH configuration with β = 135 deg. Hence, the CH with its adverse compound angle (β = 135 deg) orientation could be an appropriate film cooling configuration for gas turbine blade cooling.

Influence of Jet Impingement Configurations and Aerothermal Variables on Film Cooling

2016 ◽  
Author(s):  
Xing Yang ◽  
Zhao Liu ◽  
Zhansheng Liu ◽  
Bin Wu ◽  
Zhenping Feng
Keyword(s):  
Film Cooling ◽  
Stokes Equations ◽  
Density Ratio ◽  
Jet Impingement ◽  
Target Surface ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Baseline Case ◽  
Target Wall

In this study, the effects of impingement with various configurations at different aerothermal conditions on film cooling are investigated. The detailed adiabatic film cooling effectiveness distributions are obtained by solving steady three dimensional Reynolds-averaged Navier-Stokes equations with SST k-ω turbulence model closure. The influence of impingement on film cooling effectiveness is revealed by comparing the results from two cases: one where coolant is directly fed from a plenum (baseline case) and the other where the film coolant is extracted from the post-impingement flow on spherical dimples. For the latter case with post-impingement flow, the variations of the jet impingement configurations are considered at separation distances (H/Dj) from jet plate to target surface of 1, 2, 4 and 6, and eccentricities (F/Dj) between dimple center and film hole center of 0, 2, and 4. Besides, the effects of target wall heating the post-impingement flow on the external adiabatic film cooling performance are examined. The temperature ratios of the target surface to main flow at the inlet are set at 0.6, 0.7 and 0.8. The results are presented for four various averaged jet Reynolds numbers, which correspond to blowing ratios ranging from 0.5 to 2.0. It is observed that the impingement through the jet plate brings out pressure re-distributions on the target plate with film holes, and the dominant effect is on the flow structures in the supply chamber and near the entrance of the film hole. At the lowest blowing ratio of 0.5, film cooling with post-impingement air on dimples is reduced in comparison with the baseline case, while at higher blowing ratios, the effect of the impingement configuration on film cooling all depends on the flow conditions. In addition, the heating effect of target wall on the post-impingement flow could lower the coolant-to-mainstream density ratio, and then reduces the adiabatic film cooling performance.

Increasing Adiabatic Film-Cooling Effectiveness by Using an Upstream Ramp

2006 ◽  
Vol 129 (4) ◽  
pp. 464-471 ◽  
Author(s):  
Sangkwon Na ◽  
Tom I-P. Shih
Keyword(s):  
Film Cooling ◽  
Stokes Equations ◽  
Lateral Spreading ◽  
Navier Stokes ◽  
Backward Facing Step ◽  
Navier Stokes Equations ◽  
Film Cooling Effectiveness ◽  
Adiabatic Effectiveness ◽  
Layer Flow ◽  
Film Cooling Holes

A new design concept is presented to increase the adiabatic effectiveness of film cooling from a row of film-cooling holes. Instead of shaping the geometry of each hole; placing tabs, struts, or vortex generators in each hole; or creating a trench about a row of holes, this study proposes a geometry modification upstream of the holes to modify the approaching boundary-layer flow and its interaction with the film-cooling jets. Computations, based on the ensemble-averaged Navier–Stokes equations closed by the realizable k‐ε turbulence model, were used to examine the usefulness of making the surface just upstream of a row of film-cooling holes into a ramp with a backward-facing step. The effects of the following parameters were investigated: angle of the ramp (8.5deg, 10deg, 14deg), distance between the backward-facing step and the row of film-cooling holes (0.5D,D), blowing ratio (0.36, 0.49, 0.56, 0.98), and “sharpness” of the ramp at the corners. Results obtained show that an upstream ramp with a backward-facing step can greatly increase surface adiabatic effectiveness. The laterally averaged adiabatic effectiveness with a ramp can be two or more times higher than without the ramp by increasing upstream and lateral spreading of the coolant.

Film Cooling Performance of Sharp Edged Diffuser Holes With Lateral Inclination

2011 ◽  
Vol 134 (4) ◽  
Author(s):  
Christian Heneka ◽  
Achmed Schulz ◽  
Hans-Jörg Bauer ◽  
Andreas Heselhaus ◽  
Michael E. Crawford
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Area Ratio ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Hot Gas ◽  
Wide Range ◽  
Contour Plots ◽  
Compound Angle

An experimental study on film cooling performance of laterally inclined diffuser shaped cooling holes is presented. The measurements have been conducted on a flat plate with coolant ejected from a plenum. The film cooling effectiveness downstream of a row of four laidback fanshaped holes with sharp edged diffusers has been determined by means of infrared (IR) thermography. A variety of geometric parameters has been tested, including the inclination angle, the compound angle, the area ratio, and the pitch to diameter ratio. All tests have been performed over a wide range of engine typical blowing ratios (M=0.5–3.0). The hot gas Reynolds number and the coolant to hot gas density ratio have been kept constant close to engine realistic conditions. The results, presented in terms of contour plots of related adiabatic film cooling effectiveness as well as laterally averaged related values, clearly show the influences of the cooling hole geometry. Increasing the area ratio and the compound angle, in general, leads to higher values of the effectiveness, whereas steeper injection causes a reduction of the effectiveness.

Massively-Parallel Compressible Discontinuous Galerkin Spectral Element LES of Film Cooling

2015 ◽  
Author(s):  
Joshua L. Camp ◽  
Andrew Duggleby
Keyword(s):  
Discontinuous Galerkin ◽  
Film Cooling ◽  
Stokes Equations ◽  
Density Ratio ◽  
Spectral Element ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Blowing Ratio ◽  
Cooling Hole ◽  
Lift Off

There are many gas turbine flows that are subsonic but still at speeds where gas compresses and the assumptions made in a low-Mach formulation are inadequate. In particular, a low-Mach spectral element solver, NEK5000, was used to perform a LES study of a film cooling hole at a blowing ratio and density ratio of 1.0 and 1.5, respectively. Due to a lack of real compressibility effects in the formulation, the simulation over-predicted the velocity in the hole, leading to large coolant lift-off and poorer film cooling performance than expected. Recently, the capabilities of NEK5000 have been extended to solve the compressible Navier-Stokes equations using the discontinuous Galerkin spectral element method (DGSEM). In this paper, details of the new algorithm are given, and results of the new simulation show vast improvements over the low-Mach code and compare well to previous experimental results.

Leading-Edge Film-Cooling Physics—Part III: Diffused Hole Effectiveness

2003 ◽  
Vol 125 (2) ◽  
pp. 252-259 ◽  
Author(s):  
William D. York ◽  
James H. Leylek
Keyword(s):  
Film Cooling ◽  
Stokes Equations ◽  
Density Ratio ◽  
Leading Edge ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Stagnation Line ◽  
Half Angle ◽  
Edge Surface ◽  
And Performance

A proven computational methodology was applied to investigate film cooling from diffused holes on the simulated leading edge of a turbine airfoil. The short film-hole diffuser section was conical in shape with a shallow half-angle, and was joined to a plenum by a cylindrical metering section. The diffusion resulted in a film-hole breakout area of 2.5 times that of a cylindrical hole. In the present paper, predictions of adiabatic effectiveness for the cases with diffused holes are compared to results for standard cylindrical holes, and performance is analyzed in the context of extensive flowfield data. The leading edge surface was elliptic in shape to accurately model a turbine airfoil. The geometry consisted of one row of holes centered on the stagnation line, and two additional rows located 3.5 hole (metering section) diameters downstream on either side of the stagnation line. Film holes in the downstream rows were centered laterally between holes in the stagnation row. All holes were angled at 20 deg with the leading edge surface, and were turned 90 deg with respect to the streamwise direction (radial injection). The average blowing ratio was varied from 1.0 to 2.5, and the coolant-to-mainstream density ratio was equal to 1.8. The steady Reynolds-averaged Navier-Stokes equations were solved with a pressure-correction algorithm on an unstructured, multi-block grid containing 4.6 million finite-volumes. A realizable k-ε turbulence model was employed to close the equations. Convergence and grid-independence was verified using strict criteria. Based on the laterally averaged effectiveness over the leading edge, the diffused holes showed a marked advantage over standard holes through the range of blowing ratios. However, ingestion of hot crossflow and thermal diffusion into the second row of film holes was observed to cause significant, and potentially detrimental, heating of the film-hole walls.

Film Cooling From Shaped Holes

1999 ◽  
Vol 122 (2) ◽  
pp. 224-232 ◽  
Author(s):  
C. M. Bell ◽  
H. Hamakawa ◽  
P. M. Ligrani
Keyword(s):  
Film Cooling ◽  
Momentum Flux ◽  
Density Ratio ◽  
Performance Parameter ◽  
Stanton Number ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Density Ratios ◽  
Compound Angle

Local and spatially averaged magnitudes of the adiabatic film cooling effectiveness, the iso-energetic Stanton number ratio, and film cooling performance parameter are measured downstream of (i) cylindrical round, simple angle (CYSA) holes, (ii) laterally diffused, simple angle (LDSA) holes, (iii) laterally diffused, compound angle (LDCA) holes, (iv) forward diffused, simple angle (FDSA) holes, and (v) forward diffused, compound angle (FDCA) holes. Data are presented for length-to-inlet metering diameter ratio of 3, blowing ratios from 0.4 to 1.8, momentum flux ratios from 0.17 to 3.5, and density ratios from 0.9 to 1.4. The LDCA and FDCA arrangements produce higher effectiveness magnitudes over much wider ranges of blowing ratio and momentum flux ratio compared to the three simple angle configurations tested. All three simple angle hole geometries, CYSA, FDSA, and LDSA, show increases of spanwise-averaged adiabatic effectiveness as the density ratio increases from 0.9 to 1.4, which are larger than changes measured downstream of FDCA and LDCA holes. Iso-energetic Stanton number ratios downstream of LDCA and FDCA holes (measured with unity density ratios) are generally increased relative to simple angle geometries for m⩾1.0 when compared at particular normalized streamwise locations, x/D, and blowing ratios, m. Even though this contributes to higher performance parameters and lower protection, overall film cooling performance parameter q˙″/q˙o″ variations with x/D and m are qualitatively similar to variations of adiabatic film cooling effectiveness with x/D and m. Consequently, the best overall protection over the widest ranges of blowing ratios, momentum flux ratios, and streamwise locations is provided by LDCA holes, followed by FDCA holes. Such improvements in protection are partly due to film diffusion from expanded hole shapes, as well as increased lateral spreading of injectant from compound angles. [S0022-1481(00)02202-7]

Film Cooling Performance of Sharp-Edged Diffuser Holes With Lateral Inclination

2010 ◽  
Author(s):  
Christian Heneka ◽  
Achmed Schulz ◽  
Hans-Jo¨rg Bauer ◽  
Andreas Heselhaus ◽  
Michael E. Crawford
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Area Ratio ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Hot Gas ◽  
Wide Range ◽  
Contour Plots ◽  
Compound Angle

An experimental study on film cooling performance of laterally inclined diffuser shaped cooling holes is presented. The measurements have been conducted on a flat plate with coolant ejected from a plenum. The film cooling effectiveness downstream of a row of four laidback fanshaped holes with sharp-edged diffusers has been determined by means of IR thermography. A variety of geometric parameters has been tested, including the inclination angle, the compound angle, the area ratio, and the pitch to diameter ratio. All tests have been performed over a wide range of engine typical blowing ratios (M = 0.5–3.0). The hot gas Reynolds number and the coolant to hot gas density ratio have been kept constant close to engine realistic conditions. The results, presented in terms of contour plots of related adiabatic film cooling effectiveness as well as laterally averaged related values, clearly show the influences of the cooling hole geometry. Increasing the area ratio and the compound angle, in general, leads to higher values of the effectiveness, whereas steeper injection causes a reduction of the effectiveness.

Leading-Edge Film-Cooling Physics: Part III — Diffused Hole Effectiveness

2002 ◽  
Author(s):  
William D. York ◽  
James H. Leylek
Keyword(s):  
Film Cooling ◽  
Stokes Equations ◽  
Density Ratio ◽  
Leading Edge ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Stagnation Line ◽  
Half Angle ◽  
Edge Surface ◽  
And Performance

A proven computational methodology was applied to investigate film cooling from diffused holes on the simulated leading edge of a turbine airfoil. The short film-hole diffuser section was conical in shape with a shallow half-angle, and was joined to a plenum by a cylindrical metering section. The diffusion resulted in a film-hole breakout area of 2.5 times that of a cylindrical hole. In the present paper, predictions of adiabatic effectiveness for the cases with diffused holes are compared to results for standard cylindrical holes, and performance is analyzed in the context of extensive flowfield data. The leading edge surface was elliptic in shape to accurately model a turbine airfoil. The geometry consisted of one row of holes centered on the stagnation line, and two additional rows located 3.5 hole (metering section) diameters downstream on either side of the stagnation line. Film holes in the downstream rows were centered laterally between holes in the stagnation row. All holes were angled at 20° with the leading edge surface, and were turned 90° with respect to the streamwise direction (radial injection). The average blowing ratio was varied from 1.0 to 2.5, and the coolant-to-mainstream density ratio was equal to 1.8. The steady Reynolds-Averaged Navier-Stokes equations were solved with a pressure-correction algorithm on an unstructured, multi-block grid containing 4.6 million finite-volumes. A realizable k-ε turbulence model was employed to close the equations. Convergence and grid-independence was verified using strict criteria. Based on the laterally averaged effectiveness over the leading edge, the diffused holes showed a marked advantage over standard holes through the range of blowing ratios. However, ingestion of hot crossflow and thermal diffusion into the second row of film holes was observed to cause significant, and potentially detrimental, heating of the film-hole walls.

The Effect of Turbulence Intensity on Film Cooling of Gas Turbine Blade From Trenched Shaped Holes

2008 ◽  
Author(s):  
S. Baheri ◽  
B. A. Jubran ◽  
S. P. Alavi Tabrizi
Keyword(s):  
Turbulence Intensity ◽  
Film Cooling ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Computational Results ◽  
Cooling Effectiveness ◽  
Navier Stokes Equations ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Volume Method

This paper reports a computational investigation on the effects of mainstream turbulence intensity on film cooling effectiveness from trenched holes over a symmetrical blade. Computational solutions of the steady, Reynolds-Averaged Navier-Stokes equations are obtained using a finite volume method with k – ε Turbulence model. Whenever possible, computational results are compared with experimental ones from data found in the open literature. Computational results are presented for a row of 25 deg forward-diffused film hole within transverse slot injected at 35 deg to AGTB symmetrical blade. Four blowing ratios, M = 0.3, 0.5, 0.9 and 1.3 are studied together with four mainstream turbulence intensities of Tu = 0.5%, 2%, 4% and 10%. Results indicate that the trenched shaped holes tend to give better film cooling effectiveness than that obtained from discrete shaped holes for all blowing ratios and all turbulence intensities. The trenching of shaped holes has changed the optimum blowing ratio and also the location of re-attachment of separated jet at high blowing ratios. Moreover, it has been found that the effect of mainstream turbulence intensity for trenched shaped holes is similar to that obtained for discrete shaped holes with the exception that the sensitivity of film cooling effectiveness to turbulence intensity has decreased for trenched shaped holes.

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