Experimental and numerical investigations of overall cooling effectiveness on a vane endwall with jet impingement and film cooling

2019 ◽  
Vol 148 ◽  
pp. 1148-1163 ◽  
Author(s):  
Xing Yang ◽  
Zhansheng Liu ◽  
Qiang Zhao ◽  
Zhao Liu ◽  
Zhenping Feng ◽  
...  
Keyword(s):  
Film Cooling ◽  
Jet Impingement ◽  
Cooling Effectiveness ◽  
Numerical Investigations

Effects of Jetting Orifice Geometry Parameters and Channel Reynolds Number on Bended Channel Cooling for a Novel Internal Cooling Structure

2019 ◽  
Author(s):  
Wei He ◽  
Qinghua Deng ◽  
Juan He ◽  
Tieyu Gao ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Film Cooling ◽  
Leading Edge ◽  
Jet Impingement ◽  
Suction Side ◽  
Outer Wall ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
Blade Leading Edge

Abstract A novel internal cooling structure has been raised recently to enhance internal cooling effectiveness and reduce coolant requirement without using film cooling. This study mainly focuses on verifying the actual cooling performance of the structure and investigating the heat transfer mechanism of the leading edge part of the structure, named bended channel cooling. The cooling performances of the first stage of GE-E3 turbine with three different blade leading edge cooling structures (impingement cooling, swirl cooling and bended channel cooling) were simulated using the conjugate heat transfer method. Furthermore, the effects of jetting orifice geometry and channel Reynolds number were studied with simplified models to illustrate the flow and heat transfer characteristics of the bended channel cooling. The results show that the novel internal cooling structure has obvious advantages on the blade leading edge and suction side under operating condition. The vortex core structure in the bended channel depends on orifice width, but not channel Reynolds number. With the ratio of orifice width to outer wall thickness smaller than a critical value of 0.5, the coolant flows along the external surface of the channel in the pattern of “inner film cooling”, which is pushed by centrifugal force and minimizes the mixing with spent cooling air. Namely, the greatly organized coolant flow generates higher cooling effectiveness and lower coolant demand. Both the Nusselt number on the channel surfaces and total pressure loss increase significantly when the orifice width falls or channel Reynolds increases, but the wall jet impingement distance appears to be less influential.

Effects of Cooling Configurations on the Aerothermal Performance of a Turbine Endwall With Jet Impingement and Film Cooling

2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Hongyan Bu ◽  
Zhendong Guo ◽  
Liming Song ◽  
Jun Li
Keyword(s):  
Film Cooling ◽  
Design Space ◽  
Cooling System ◽  
Uniform Design ◽  
Jet Impingement ◽  
Hole Diameter ◽  
Performance Criteria ◽  
Channel Height ◽  
Inlet Temperature ◽  
Cooling Effectiveness

Abstract With the increase of turbine inlet temperature and the application of premixed combustion, turbine components, particularly the turbine endwall, work in a harsh environment and must be effectively cooled to ensure the component durability. Recently, new cooling schemes that employ both external film cooling and internal jet impingement cooling have drawn much attention due to their extraordinary performance. In this study, a numerical model of turbine endwall with jet impingement and film cooling was established and validated against the experiment. To investigate the effects of geometric parameters related to this cooling scheme, four parameters including impingement hole-to-hole pitch Pi, impingement hole diameter Di, impingement channel height H, and film hole diameter Df were selected to adjust within a reasonable range. The uniform design method was used to collect a database that represented the design space formed by the four parameters. Performance criteria including area-averaged overall cooling effectiveness, standard deviation of overall cooling effectiveness, and total pressure drop coefficient of the cooling system were evaluated through computational fluid dynamics (CFD) calculations. To explore and exploit the design space, a Kriging model was built from the database. Analysis of variance (ANOVA) was conducted afterward to investigate the main effect of each parameter and the correlation between parameters. Finally, based upon the knowledge obtained from ANOVA, typical designs were selected which yielded either best or poorest performances. Through detailed analysis of flow and heat transfer mechanisms of these designs, the influence of each parameter was illustrated clearly and suggestions for the design of similar cooling schemes were drawn.

Effects of Cooling Configurations on the Aerothermal Performance of a Turbine Endwall With Jet Impingement and Film Cooling

2020 ◽  
Author(s):  
Hongyan Bu ◽  
Zhendong Guo ◽  
Liming Song ◽  
Jun Li
Keyword(s):  
Surrogate Model ◽  
Film Cooling ◽  
Design Space ◽  
Cooling System ◽  
Design Method ◽  
Uniform Design ◽  
Jet Impingement ◽  
Channel Height ◽  
Inlet Temperature ◽  
Cooling Effectiveness

Abstract With the rapid increase of turbine inlet temperature and the application of premixed combustion, turbine components, particularly the turbine endwall, works in extremely harsh environment and must be effectively cooled to ensure the component durability. Recently, new cooling schemes that employ both external film cooling and internal jet impingement cooling have drawn much attention due to their extraordinary performance. In this study, a numerical model of turbine endwall with jet impingement and film cooling was established and validated against the experimental results. To investigate the effects of geometric parameters related with this cooling scheme, four parameters including impingement hole-to-hole pitch Pi, impingement hole diameter Di, impingement channel height H, film hole diamete Df, were selected to adjust within a reasonable range. The uniform design method was used to collect a database that represented the design space formed by the four parameters. Performance criterions including area-averaged overall cooling effectiveness, standard deviation of overall cooling effectiveness, total pressure drop coefficient of the cooling system were evaluated through CFD calculations. To explore and exploit the design space as much as possible, a Kriging surrogate model was built from the database. Analysis of variance (ANOVA) was conducted based upon the surrogate model to investigate the main effect of each parameter and the correlation between parameters. Finally, based upon the knowledge obtained from ANOVA, typical designs were selected from the database which yielded either best or poorest performances. Through detailed analysis of flow and heat transfer mechanisms of these typical designs, the influence of each parameter was illustrated clearly and suggestions for the design of similar cooling schemes were drawn.

Numerical Investigations of Cooling Enhancement With Internal Ribs and External Coolant Film

2012 ◽  
Author(s):  
Zhixin Feng ◽  
Zhongwang Dou ◽  
Jianhua Wang ◽  
Shiyan Ma ◽  
Zhiqiang Zhang
Keyword(s):  
Film Cooling ◽  
Influence Factors ◽  
Numerical Approach ◽  
Cooling Effectiveness ◽  
Numerical Investigations ◽  
Wall Film ◽  
Ansys Cfx ◽  
Cooling Enhancement ◽  
Energy Equations ◽  
Cooling Air

Experimental and numerical investigations were carried out to study the average cooling performance of two different rectangular structures: 1) purely ribbed channel (only ribs were periodically embedded inner the wall of the structure); 2) combined structure of film cooling with the ribs (in the ribbed wall, film holes were periodically drilled). To create a similar environment of gas turbine blade, the experiments were performed at a high temperature mainstream, and the ambient temperature cooling air passed through the channel with the direction normal to the mainstream. In the experimental and numerical investigations, the overall cooling effect contributed by the heat conduction through channel’s wall and convections including internal ribbed wall and external film cooling was considered. In the numerical investigation, 3D conservation equations including mass, momentum, energy, turbulence eddy frequency and turbulence kinetic energy equations were solved with ANSYS-CFX, and the hybrid mesh technique and shear stress transport (SST) k-ω model were adopted. This numerical approach was validated by the experimental data. Using the validated numerical approach, the influence factors on the overall cooling effectiveness are discussed, and the effects of the internal ribs and external film cooling are numerically compared by the two structures. The relationship of the overall cooling effectiveness averaged over the rectangular surface with the mainstream Reynolds number, mass flow ratio and temperature ratio of the mainstream to cooling air, as well as the blowing ratio injected through the film holes was fitted by the numerical results.

scholarly journals Conjugate Heat Transfer Analysis of Flat Plate Subjected to Impingement and Film Cooling

2021 ◽  
Vol 9 (9) ◽  
pp. 1667-1678
Author(s):  
Devaraj K
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Flat Plate ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Jet Impingement ◽  
Heat Transfer Analysis ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness

Abstract: The present computational study involves a flat plate subjected to combined effect of jet impingement and film cooling. A conjugate heat transfer model in conjunction with k-ω SST turbulence model is employed to study the turbulence effects. The effect of Reynolds number varying from 389 to 2140 on static temperature, Nusselt number and film cooling effectiveness has be discussed for the blowing ratios of 0.6, 0.8, 1.0. The variation in the size of vortices formed on the impinging surface with Reynolds number is studied. It has been observed that the local Nusselt number shows a rising trend with the increase in Reynolds number, while the static temperatures follow the downfall in its values. As a result, an enhancement in the effectiveness is observed, which is credited to the capabilities of combined impingement and film cooling. At Reynolds number of 972, the coolant jet is found to be attached to the surface, for this condition the heat transfer phenomena for blowing ratios of 0.6, 0.8, 1.0, 1.2, 1.6, 2.0, 2.4, 2.6 are studied to understand the flow distribution on the plate surface. Keywords: Jet impingement, film cooling, effectiveness, conjugate heat transfer

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.

Numerical Investigations of Wake and Shock Wave Effects on Film Cooling Performance in a Transonic Turbine Stage: Part 1 — Methodology Development and Qualification Over Stationary Stators and Rotors

2013 ◽  
Author(s):  
Huazhao Xu ◽  
Jianhua Wang ◽  
Ting Wang
Keyword(s):  
Experimental Data ◽  
Mach Number ◽  
Film Cooling ◽  
Suction Side ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Numerical Investigations ◽  
Blowing Ratio

To understand the unsteady shock wave and wake effects on the film cooling performance over a transonic 3-D rotating stage, a series of numerical investigations have been conducted and are presented in this two-part paper. Part 1 is focused on the development of the computational model and methodology of the system setup and model qualification; Part 2 is to investigate the unsteady effects of shock waves and wakes on film cooling performance in a transonic rotating stage. In Part 1, the film cooling experimental conditions (non-rotating) and test sections of Kopper et. al. and Hunter are selected for model qualification. The numerical computation is carried out by the commercial software Ansys/Fluent using the pressure based compressible flow governing equations. The effects of four turbulence models are carefully compared with the experimental data. The Realizable k-ε turbulence model is found to match the experimental data better than the other models and is thus used for the rest of the study, including Part 2. The results show that 1) the weak shock emanating from the neighboring stator’s trailing edge results in a temperature rise and a reduction of film cooling effectiveness on the suction side near the trailing edge, 2) cooling ejection from the trailing edge reduces the shock strength in the stator passage, 3) an increase in Mach number from 0.84 to 1.50 can reduce the total pressure losses of fluid flow near the end-walls, 4) the film cooling effectiveness increases with increasing blowing ratio and becomes more even on the stator with a higher blowing ratio, and 5) an increase in Mach number from 0.84 to 1.50 gives rise to a higher cooling effectiveness in the region from the cooling holes to 80% of the chord length of the stator on the pressure side, but becomes lower after this up to the trailing edge. However, on the stator’s suction side, higher Mach number results in a lower cooling effectiveness region around the film holes from 30% to 55% of the chord length, but cooling effectiveness increases downstream.

scholarly journals Parametric Study on Geometrical Arrangement of Sister Hole

2015 ◽  
Vol 773-774 ◽  
pp. 373-377
Author(s):  
Kamil Abdullah ◽  
Firdauz Amon ◽  
Mas Fawzi Mohd Ali
Keyword(s):  
Reynolds Number ◽  
Film Cooling ◽  
Gas Turbines ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Geometrical Arrangement ◽  
Numerical Investigations ◽  
Ansys Cfx ◽  
Cooling Hole ◽  
The Common

Modern gas turbines require a sophisticated cooling scheme to remove the heat from its component to ensure it durability. One of the common techniques applied in the cooling scheme is film cooling The present study focuses numerical investigation of an sister cooling hole design. The investigations make use of commercial CFD software, ANSYS CFX. The numerical investigations have been carried out at Reynolds number, Re = 21,000 involving three differens blowing ratios, BR = 0.5, 1.0, and 1.5. Four different cases have been considered; STA, STB STC and SH. The results show promising improvement in terms of film cooling effectiveness with the implementation of sister holes in certain geometrical arrangements.

Effect of Array Jet on Cooling Effectiveness on Full-Coverage Film Cooled Surface

2009 ◽  
Author(s):  
Dong Hyun Lee ◽  
Sang Hyun Oh ◽  
Eui Yeop Jung ◽  
Kyung Min Kim ◽  
Hyung Hee Cho
Keyword(s):  
Stainless Steel ◽  
Film Cooling ◽  
Steel Plate ◽  
Jet Impingement ◽  
Hole Diameter ◽  
Stainless Steel Plate ◽  
Cooling Effectiveness ◽  
Impingement Jet ◽  
Full Coverage ◽  
Film Cooling Holes

In this study, the cooling effectiveness (Φ) was measured on full-coverage film cooled surface with and without array jet impingement cooing using an infra-red thermographic technique. Measurements were conducted with two test plates of different thermal conductivities. One was made of stainless steel (k = 16.3 W/m·K) and the other was made of polycarbonate (k = 0.2 W/m · K). The measured cooling effectiveness comprises the adiabatic film cooling effectiveness on the film cooled surfaces, the heat conduction through the test plates and convective heat transfer of array jet impingement underneath the test plates. The inclination angles of film cooling holes and impingement jet holes were 35° and 90°, respectively. The diameters of both film cooling and impingement jet cooling holes were 5 mm. The streamwise and spanwise hole spacing-to-hole diameter ratios (p/d) are 3 for both the effusion plate (film cooled plate) and the injection plate (impingement nozzle plate. The holes on each plate were arranged in an inline pattern, while the film cooling holes and jet holes were positioned in a staggered manner. The jet Reynolds number based on the hole diameter was 3,000 and the equivalent blowing ratio (M) was 0.3. The gap distance between the jet plate and the film cooling plate was varied from 1 to 5 times of the hole diameter. In addition, the cooling effectiveness without impingement was tested, too. The stainless steel plate shows relatively higher and uniform cooling effectiveness than the polycarbonate plate. The effect of H/d was not significant for both test plates. However, the cooling effectiveness without the impingement jets decreases significantly for the stainless steel plate, while it changed a little for the cooling effectiveness of the polycarbonate plate.

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