Exploring Conjugate CFD Heat Transfer Characteristics for a Film-Cooled Flat Plate and 3-D Turbine Inlet Vane

2012 ◽  
Author(s):  
J. J. Johnson ◽  
P. I. King ◽  
J. P. Clark ◽  
P. J. Koch
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Film Cooling ◽  
Low Cost ◽  
Full Scale ◽  
Design Flow ◽  
Navier Stokes ◽  
Cooling Performance ◽  
Cooling Design ◽  
Computational Fluid Dynamics Cfd

As part of a thorough benchmarking of the baseline cooling design in planned optimization work, Reynolds-Averaged Navier Stokes (RANS) conjugate heat transfer (CHT) computational fluid dynamics (CFD) assessments have been accomplished at RTV design flow conditions to simulate both a cooled flat plate pressure side (PS) model infrared thermography experiment as well as a full-scale, fully-cooled, full-wheel blowdown experiment on the same high pressure turbine (HPT) vane. Numerous past works on turbomachinery film cooling have been conducted using flat plate models because of their simplicity, repeatability, and low cost of experimentation relative to full scale rotating blowdown rigs. Some of these works generated film cooling correlations still in use today in industry for HPT components. The CFD assessments in this work provide insight into the fundamental differences between a flat plate model and a realistic 3-D vane in terms of film cooling performance for the same PS cooling array. The comparisons of results wring out expected differences between the geometries due to aspects such as highly curved surfaces and endwall effects. However, with nearly-matched coolant-to-mainstream temperature and pressure ratios, the cooling performance between the two models is surprisingly similar, especially in the midspan region. The similarities and differences observed herein represent the rigor and accuracy afforded by simulating both the solid and fluid domains as well as the high-density unstructured meshes that take into account all individual cooling passages and internal plenums, on top of the typically-assessed external fluid flow field.

Numerical Approach at Flat Plate for Predicting the Film Cooling Effectiveness Part A: Effect Blowing Ratio

2018 ◽  
Vol 16 ◽  
pp. 30-44 ◽  
Author(s):  
Farouk Kebir ◽  
Azzeddine Khorsi
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Film Cooling ◽  
Thermal Stresses ◽  
Free Stream ◽  
Turbine Blades ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Free Stream Turbulence ◽  
Blowing Ratio

Film cooling is vital for gas turbine blades to protect them from thermal stresses and high temperatures due to the hot gas flow in the blade surface. Film cooling is applied to almost all external surfaces associated with aerodynamic profiles that are exposed to hot combustion gases such as main bodies, end-walls, blade tips and leading edges. In a review of the literature, it was found that there are strong effects of free-stream turbulence, surface curvature and hole shape on film cooling performance also blowing ratio. The performance of the film cooling is difficult to predict due to the inherent complex flow fields along the surfaces of the airfoil components in the turbine engines. From all what we introducing the film cooling is reviewed through a discussion of the analyses methodologies, a physical description, and the various influences on film-cooling performance. Initially Computational analysis was done on a flat plate with hole inclined at 55° to the surface plate. This study focuses on the efficient computation of film cooling flows with three blowing ratio. The numerical results show the effectiveness cooling and heat transfer behavior with increasing injection blowing ratio M (0.5, 1, and 1.5). The influence of increased blade film cooling can be assessed via the values of Nusselt number in terms of reduced heat transfer to the blade. Predictions of film effectiveness are compared with experimental results for a circular jet at blowing ratios ranging from 0.5, 1.0 and 1.5. The present results are obtained at a free stream turbulence of 10%, which are the typical conditions upstream of the effectiveness is generally lower for a large stream-wise angle of 55°.

3D Heat Transfer Assessment of Full-Scale Inlet Vanes With Surface-Optimized Film Cooling: Part 2 — Conjugate CFD Simulations

2019 ◽  
Author(s):  
J. J. Johnson ◽  
J. P. Clark ◽  
R. A. Anthony ◽  
M. K. Ooten ◽  
R. H. Ni ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Side Surface ◽  
Full Scale ◽  
Pressure Side ◽  
Computationally Efficient ◽  
Cfd Simulations ◽  
Experimental Heat ◽  
Cooling Hole ◽  
Cooling Design

Abstract An investigation of the experimental heat transfer and cooling effectiveness for a modern fully-cooled high-pressure turbine (HPT) inlet vane is presented. Conjugate Heat Transfer (CHT) Computational Fluid Dynamics (CFD) is conducted to simulate experiments using thin-film heat-flux gauges on full-scale 3D vanes at engine-representative conditions from Part 1 of this paper. Pressure side (PS) film cooling performance is compared for a baseline and optimized configuration, in which the latter was previously developed using genetic algorithm (GA) optimization. The optimized vane was iterated using hundreds of computationally efficient 3D Reynolds Averaged Navier Stokes (RANS) CFD simulations with a transpiration boundary condition to simulate film cooling. This combination of CFD and GAs determined surface-optimized cooling hole orientations and placement. Steady-state flat plate infrared thermography experiments that followed also determined the best cooling hole shapes to use on different sections of the vane pressure side surface. This ultimately generated the cooling design to be fabricated using realistic materials and experimentally tested in Part 1 and simulated using CHT CFD in the current work (Part 2). Here, spanwise and streamwise heat transfer distributions for the baseline and optimized cooling design are validated against experimental data. 3D CHT CFD results are then assessed at the same conditions, providing relevance and credence to the overall cooling design methods. Ultimately, surface-optimized film cooling designs can be used to reduce the adverse effects of sub-optimal heat distribution on critical high temperature engine parts, increasing the life of the part. Alternatively, such a design could lead to increases in engine efficiency since less cooling air is required from the mainstream per part.

scholarly journals Analysis of Heat Transfer on film cooling performance in a flat plate

2019 ◽  
Vol 158 ◽  
pp. 4154-4159
Author(s):  
Xiaoming Tan ◽  
Xiaoming Zhou ◽  
Yong Shan ◽  
Jingzhou Zhang
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Film Cooling ◽  
Cooling Performance

Numerical investigations of endwall film cooling design of a turbine vane using four-holes pattern

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jian Liu ◽  
Xi Wenxiong ◽  
Mengyao Xu ◽  
Jiawen Song ◽  
Shibin Luo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Leading Edge ◽  
Full Scale ◽  
Junction Region ◽  
Content Type ◽  
Mesh Independence ◽  
Cooling Design ◽  
Endwall Film Cooling ◽  
Film Cooling Holes

Purpose Endwall film cooling protects vane endwall by coolant coverage, especially at the leading edge (LE) region and vane-pressure side (PS) junction region. Strong flow impingement and complex vortexaa structures on the vane endwall cause difficulties for coolant flows to cover properly. This work aims at a full-scale arrangement of film cooling holes on the endwall which improves coolant efficiency in the LE region and vane-PS junction region. Design/methodology/approach The endwall film holes are grouped in four-holes constructal patterns. Three ways of arranging the groups are studied: based on the pressure field, the streamlines or the heat transfer field. The computational analysis is done with the k-ω SST model after validating the turbulence model properly. Findings By clustering the film cooling holes in four-holes patterns, the ejection of the coolant flow is stronger. The four-holes constructal patterns also improve the local coolant coverage in the “tough” regions, such as the junction region of the PS and the endwall. The arrangement based on streamlines distribution can effectively improve the coolant coverage and the arrangement based on the heat transfer distribution (HTD) has benefits by reducing high-temperature regions on the endwall. Originality/value A full-scale endwall film cooling design is presented considering interactions of different film cooling holes. A comprehensive model validation and mesh independence study are provided. The cooling holes pattern on the endwall is designed as four-holes constructal patterns combined with several arrangement choices, i.e. by pressure, by heat transfer and by streamline distributions.

Effect of Hole Shape on Film Cooling Effectiveness Over a Flat Plate

2013 ◽  
Author(s):  
J. Felix ◽  
N. Harshavardhana ◽  
Y. Giridhara Babu ◽  
D. Rajanna ◽  
N. Vinod Kumar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Film Cooling ◽  
Thermal Image ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
The Heat Transfer Coefficient

Film cooling method of hot section components in the gas turbine engines is under continuous optimization for the enhanced cooling performance. In the present study, film cooling performance for a row of different shaped holes like triangular, circular and extended triangular have been considered. The adiabatic film effectiveness and the convective heat transfer coefficients are found experimentally on a flat plate. All the three test models are having holes of 5 mm diameter drilled at 20 mm pitch and inclined at an angle of 22 degrees. At the immediate downstream of these models, a flat plate is attached for finding the effect of these hole configurations. This flat plate is made with the low conductivity substrate and the stainless sheet of 0.2 mm thick is pasted over it in the flow path. The test model along with the flat plate is placed to the side wall of the rectangular duct where the mainstream air is supplied. The setup is made in such a way that the coolant air passed through the holes will create a film over the flat plate downstream. Infra Red camera is used to capture the thermal image of the entire test plate. The flat plate is connected with six thermocouples to have the reference surface temperature to correct the IR thermal image data. K-type thermocouples are used to measure the coolant and mainstream air temperatures. In both the heat transfer coefficient and adiabatic film cooling effectiveness experiments the blowing ratio is varied by 0.5 to 2.0, by keeping the constant mainstream air velocity of 20 m/s at ambient temperature. In the heat transfer coefficient experiments, the flat plate is heated with the constant heat flux conditions. In the adiabatic film cooling experiments, the coolant air is maintained at the temperature of −50°C with the help of liquid nitrogen heat exchanger bath. Results are plotted by taking the adiabatic film cooling effectiveness and convective heat transfer coefficient values from the centerline of holes downstream along the flow direction. From the results, the triangular and extended triangular hole models shown higher heat transfer coefficient and adiabatic film cooling effectiveness than the circular hole model.

Experimental Evaluation of Heat Transfer in a High Temperature High Pressure Test Facility

2019 ◽  
Author(s):  
S. Ramesh ◽  
E. Robey ◽  
D. Straub ◽  
J. Black
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flat Plate ◽  
Film Cooling ◽  
Test Facility ◽  
Cooling Performance ◽  
Plate Test ◽  
Test Article ◽  
Pressure Test ◽  
High Temperature High Pressure

Abstract Performance of film cooling holes is generally evaluated near ambient conditions, so scaling the film cooling performance from ambient to engine conditions is important. These performance metrics can be reported in terms of net heat flux reduction, heat transfer enhancement, and effectiveness. There are several challenges and penalties in conducting experiments on a real engine or even on a stationary flat plate test article at near engine conditions. In this study, an experimental methodology capable of delivering film cooling performance for the experiments conducted in the high-temperature high-pressure test facility at NETL will be explored. More specifically, this study focuses on various challenges that are present and how these concerns are addressed to evaluate the heat transfer coefficient on the test article. Steady state experiments were conducted on a flat plate test article whose surface temperature distribution was obtained using an IR camera calibrated with a combination of bench top experiments and in-situ calibrations based on embedded thermocouple measurements. A detailed radiation analysis is conducted to enable differentiation of heat transfer by convection from heat transfer by radiation. The estimated surface heat flux and heat transfer coefficient were found to be higher than the one obtained from flat plate correlation.

Effusion-Cooling Performance at Gas Turbine Combustor Representative Flow Conditions

2012 ◽  
Author(s):  
Vinod U. Kakade ◽  
Steven J. Thorpe ◽  
Miklós Gerendás
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Free Stream ◽  
Flow Conditions ◽  
Cooling Performance ◽  
Free Stream Turbulence ◽  
High Turbulence ◽  
Adiabatic Effectiveness

The thermal management of aero gas turbine engine combustion systems commonly employs effusion-cooling in combination with various cold-side convective cooling schemes. The combustor liner incorporates many small holes which are usually set in staggered arrays and at a shallow angle to the cooled surface; relatively cold compressor delivery air is then allowed to flow through these holes to provide the full-coverage film-cooling effect. The efficient design of such systems requires robust correlations of film-cooling effectiveness and heat transfer coefficient at a range of aero-thermal conditions, and the use of appropriately validated computational models. However, the flow conditions within a combustor are characterised by particularly high turbulence levels and relatively large length scales. The experimental evidence for performance of effusion-cooling under such flow conditions is currently sparse. The work reported here is aimed at quantifying typical effusion-cooling performance at a range of combustor relevant free-stream conditions (high turbulence), and also to assess the importance of modeling the coolant to free-stream density ratio. Details of a new laboratory wind-tunnel facility for the investigation of film-cooling at high turbulence levels are reported. For a typical combustor effusion geometry that uses cylindrical holes, spatially resolved measurements of adiabatic effectiveness, heat transfer coefficient and net heat flux reduction are presented for a range of blowing ratios (0.48 to 2), free-stream turbulence conditions (4 and 22%) and density ratios (0.97 and 1.47). The measurements reveal that elevated free-stream turbulence impacts on both the adiabatic effectiveness and heat transfer coefficient, although this is dependent upon the blowing ratio being employed and particularly the extent to which the coolant jets detach from the surface. At low blowing ratios the presence of high turbulence levels causes increased lateral spreading of the coolant adjacent to the injection points, but more rapid degradation in the downstream direction. At high blowing ratios, high turbulence levels cause a modest increase in effectiveness due to turbulent transport of the detached coolant fluid. Additionally, the augmentation of heat transfer coefficient caused by the coolant injection is seen to be increased at high free-stream turbulence levels.

Experimental and Numerical Study on the Effects of the Relative Position of Film Hole and Orientation Ribs on the Film Cooling With Ribbed Cross-Flow Coolant Channel

2020 ◽  
Author(s):  
Bingran Li ◽  
Cunliang Liu ◽  
Lin Ye ◽  
Huiren Zhu ◽  
Fan Zhang
Keyword(s):  
Heat Transfer ◽  
Relative Position ◽  
Film Cooling ◽  
Numerical Study ◽  
Cross Flow ◽  
Internal Cooling ◽  
Transfer Coefficients ◽  
Cooling Performance ◽  
Heat Transfer Coefficients ◽  
Numerical Studies

Abstract To investigate the application of ribbed cross-flow coolant channels with film hole effusion and the effects of the internal cooling configuration on film cooling, experimental and numerical studies are conducted on the effect of the relative position of the film holes and different orientation ribs on the film cooling performance. Three cases of the relative position of the film holes and different orientation ribs (post-rib, centered, and pre-rib) in two ribbed cross-flow channels (135° and 45° orientation ribs) are investigated. The film cooling performances are measured under three blowing ratios by the transient liquid crystal measurement technique. A RANS simulation with the realizable k-ε turbulence model and enhanced wall treatment is performed. The results show that the cooling effectiveness and the downstream heat transfer coefficient for the 135° rib are basically the same in the three position cases, and the differences between the local effectiveness average values for the three are no more than 0.04. The differences between the heat transfer coefficients are no more than 0.1. The “pre-rib” and “centered” cases are studied for the 45° rib, and the position of the structures has little effect on the film cooling performance. In the different position cases, the outlet velocity distribution of the film holes, the jet pattern and the discharge coefficient are consistent with the variation in the cross flow. The related research previously published by the authors showed that the inclination of the ribs with respect to the holes affects the film cooling performance. This study reveals that the relative positions of the ribs and holes have little effect on the film cooling performance. This paper expands and improves the study of the effect of the internal cooling configuration on film cooling and makes a significant contribution to the design and industrial application of the internal cooling channel of a turbine blade.

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