Investigating Heat Transfer in a Straight Cooling Passage Using Transient Infrared Temperature Data and URANS Conjugate Heat Transfer Analysis

2021 ◽  
Author(s):  
Louis Christensen ◽  
Richard Celestina ◽  
Spencer Sperling ◽  
Randall Mathison ◽  
Hakan Aksoy ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Simulations ◽  
Turbulence Model ◽  
Experimental Work ◽  
Conjugate Heat Transfer ◽  
External Surface ◽  
Average Error ◽  
Spatial Accuracy ◽  
Conduction Model ◽  
Cooling Passage

Abstract Experimental work measuring heat transfer due to internal convection on a smooth straight passage is recreated using unsteady Reynolds averaged Navier-Stokes conjugate heat transfer simulations. The experimental work utilizes 1-dimensional and 3-dimensional conduction models to determine internal heat transfer rates from external surface temperature measurements collected with an infrared camera. The numerical simulations recreated these experiments to verify the conduction model and investigate the differences between the k-ω shear stress transport turbulence model, Reynolds stress turbulence model, and the k-ε turbulence model. It is found that the conduction model can accurately predict the heat transfer in the passage within an average error of 6% but with reduced spatial accuracy. The lower spatial accuracy can be accounted for by utilizing both the conduction model to predict the magnitude of the heat transfer and the numerical simulations to capture the spatial distribution. No one turbulence model was found to provide consistently superior heat transfer predictions, but rather each model excelled in some scenarios and underperformed in others. Overall, the k-ε model was found to best match the experimental heat transfer calculations with an average error of 5.9% of the total heat transfer, and it takes a more conservative approach as it can over predict the external surface temperatures by approximately 0.4 K. The end goal of this study is to develop a way to derive heat-flux data from infrared measurements on a range of geometries. A simple and well-understood geometry is investigated here to provide a firm foundation for future work.

scholarly journals Fully Coupled Large Eddy Simulation of Conjugate Heat Transfer in a Ribbed Channel with a 0.1 Blockage Ratio

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2096
Author(s):  
Joon Ahn ◽  
Jeong Chul Song ◽  
Joon Sik Lee
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Conjugate Heat Transfer ◽  
Heat Transfer Analysis ◽  
Scale Model ◽  
Computational Domain ◽  
Blockage Ratio ◽  
Ribbed Channel ◽  
Large Eddy ◽  
Cooling Passage

Large eddy simulations are performed to analyze the conjugate heat transfer of turbulent flow in a ribbed channel with a heat-conducting solid wall. An immersed boundary method (IBM) is used to determine the effect of heat transfer in the solid region on that in the fluid region in a unitary computational domain. To satisfy the continuity of the heat flux at the solid–fluid interface, effective conductivity is introduced. By applying the IBM, it is possible to fully couple the convection on the fluid side and the conduction inside the solid and use a dynamic subgrid scale model in a Cartesian grid. The blockage ratio (e/H) is set at 0.1, which is typical for gas turbine blades. Through conjugate heat transfer analysis, it is confirmed that the heat transfer peak in front of the rib occurs because of the impinging of the reattached flow and not the influence of the thermal boundary condition. When the rib turbulator acts as a fin, its efficiency and effectiveness are predicted to be 98.9% and 8.32, respectively. When considering conjugate heat transfer, the total heat transfer rate is reduced by 3% compared with that of the isothermal wall. The typical Biot number at the internal cooling passage of a gas turbine is <0.1, and the use of the rib height as the characteristic length better represents the heat transfer of the rib.

Conjugate Heat Transfer Analysis of a High Pressure Air-Cooled Gas Turbine Vane

2010 ◽  
Author(s):  
Zhenfeng Wang ◽  
Peigang Yan ◽  
Hongyan Huang ◽  
Wanjin Han
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Boundary Conditions ◽  
Gas Turbine ◽  
Turbulence Model ◽  
Conjugate Heat Transfer ◽  
Suction Side ◽  
Turbulence Characteristic ◽  
Transition Flow ◽  
Characteristic Boundary

The ANSYS-CFX software is used to simulate NASA-Mark II high pressure air-cooled gas turbine. The work condition is Run 5411 which have transition flow characteristics. The different turbulence models are adopted to solve conjugate heat transfer problem of this three-dimensional turbine blade. Comparing to the experimental results, k-ω-SST-γ-θ turbulence model results are more accurate and can simulate accurately the flow and heat transfer characteristics of turbine with transition flow characteristics. But k-ω-SST-γ-θ turbulence model overestimates the turbulence kinetic energy of blade local region and makes the heat transfer coefficient higher. It causes that local region temperature of suction side is higher. In this paper, the compiled code adopts the B-L algebra model and simulates the same computation model. The results show that the results of B-L model are accurate besides it has 4% temperature error in the suction side transition region. In addition, different turbulence characteristic boundary conditions of turbine inner-cooling passages are given and K-ω-SST-γ-θ turbulence model is adopted in order to obtain the effect of turbulence characteristic boundary conditions for the conjugate heat transfer computation results. The results show that the turbulence characteristic boundary conditions of turbine inner-cooling passages have a great effect on the conjugate heat transfer results of high pressure gas turbine. ANSYS is applied to analysis the thermal stress of Mark II blade which has ten radial cooled passages and the results of Von Mises stress show that the temperature gradient results have a great effect on the results of blade thermal stress.

The Simulation Study of Turbulence Models for Conjugate Heat Transfer Analysis of a High Pressure Air-Cooled Gas Turbine

2010 ◽  
Author(s):  
Zhenfeng Wang ◽  
Peigang Yan ◽  
Hongfei Tang ◽  
Hongyan Huang ◽  
Wanjin Han
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Turbulence Model ◽  
Conjugate Heat Transfer ◽  
Turbulence Models ◽  
Turbulence Characteristic ◽  
The Heat Transfer Coefficient

The different turbulence models are adopted to simulate NASA-MarkII high pressure air-cooled gas turbine. The experimental work condition is Run 5411. The paper researches that the effect of different turbulence models for the flow and heat transfer characteristics of turbine. The turbulence models include: the laminar turbulence model, high Reynolds number k-ε turbulence model, low Reynolds number turbulence model (k-ω standard format, k-ω-SST and k-ω-SST-γ-θ) and B-L algebra turbulence model which is adopted by the compiled code. The results show that the different turbulence models can give good flow characteristics results of turbine, but the heat transfer characteristics results are different. Comparing to the experimental results, k-ω-SST-θ-γ turbulence model results are more accurate and can simulate accurately the flow and heat transfer characteristics of turbine with transition flow characteristics. But k-ω-SST-γ-θ turbulence model overestimates the turbulence kinetic energy of blade local region and makes the heat transfer coefficient higher. It causes that local region temperature is higher. The results of B-L algebra turbulence model show that the results of B-L model are accurate besides it has 4% temperature error in the transition region. As to the other turbulence models, the results show that all turbulence models can simulate the temperature distribution on the blade pressure surface except the laminar turbulence model underestimates the heat transfer coefficient of turbulence flow region. On the blade suction surface with transition flow characteristics, high Reynolds number k-ε turbulence model overestimates the heat transfer coefficient and causes the blade surface temperature is high about 90K than the experimental result. Low Reynolds number k-ω standard format and k-ω-SST turbulence models also overestimate the blade surface temperature value. So it can draw a conclusion that the unreasonable choice of turbulence models can cause biggish errors for conjugate heat transfer problem of turbine. The combination of k-ω-SST-γ-θ model and B-L algebra model can get more accurate turbine thermal environment results. In addition, in order to obtain the affect of different turbulence models for gas turbine conjugate heat transfer problem. The different turbulence models are adopted to simulate the different computation mesh domains (First case and Second case). As to each cooling passages, the first case gives the wall heat transfer coefficient of each cooling passages and the second case considers the conjugate heat transfer course between the cooling passages and blade. It can draw a conclusion that the application of heat transfer coefficient on the wall of each cooling passages avoids the accumulative error. So, for the turbine vane geometry models with complex cooling passages or holes, the choice of turbulence models and the analysis of different mesh domains are important. At last, different turbulence characteristic boundary conditions of turbine inner-cooling passages are given and K-ω-SST-γ-θ turbulence model is adopted in order to obtain the effect of turbulence characteristic boundary conditions for the conjugate heat transfer computation results. The results show that the turbulence characteristic boundary conditions of turbine inner-cooling passages have a great effect on the conjugate heat transfer results of high pressure gas turbine.

Improvement of a Turbulence Model for Conjugate Heat Transfer Simulation

2012 ◽  
Vol 62 (8) ◽  
pp. 624-638 ◽  
Author(s):  
P. Wang ◽  
Y. Li ◽  
Z. P. Zou ◽  
L. Wang ◽  
S. H. Song
Keyword(s):  
Heat Transfer ◽  
Turbulence Model ◽  
Conjugate Heat Transfer ◽  
Heat Transfer Simulation

Conjugate Heat Transfer Modeling of a Film-Cooled, Flat-Plate Test Specimen in a Gas Turbine Aerothermal Test Facility

2013 ◽  
Author(s):  
T. G. Sidwell ◽  
S. A. Lawson ◽  
D. L. Straub ◽  
K. H. Casleton ◽  
S. Beer
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Gas Turbine ◽  
Turbulence Model ◽  
Film Cooling ◽  
Test Specimen ◽  
Conjugate Heat Transfer ◽  
Test Facility ◽  
Plate Test ◽  
Mesh Density

The aerothermal test facility at the National Energy Technology Laboratory (NETL) provides experimental data at realistic gas turbine conditions to enable the development of advanced film cooling strategies for future gas turbine components. To complement ongoing experimental studies, Fluent computational fluid dynamics (CFD) models have been developed to provide a framework for comparison of cooling strategies and to provide fundamental understanding of the fluid dynamic and conjugate heat transfer (CHT) processes occurring in the experiments. The results of a parametric study of the effects of mesh density, near-wall refinement, wall treatment, turbulence model and gradient discretization order on the CHT predictions are presented, and the simulation results are compared to experimental data. A flat plate test specimen with a single row of laidback fan-shaped film cooling holes was modeled at a process pressure of 3 bar, a process gas flow rate (m) of 0.325 kg/s (Re ≈ 100,000) and a blowing ratio (M) of 2.75. Three polyhedral mesh cases and three turbulence models (Realizable k-ε, SST k-ω and RSM Stress-ω) were implemented with enhanced wall treatment (EWT) and 1st-order and 2nd-order gradient discretization. The results show that the choice of turbulence model will have little effect on the results when utilizing the finest mesh case and 2nd-order discretization. It was also shown that the SST k-ω turbulence model cases showed minimal mesh sensitivity with 2nd-order discretization, while the Re k-ε turbulence model cases were more sensitive to mesh density and near-wall refinement. The results thus indicate that the SST k-ω turbulence model can predict the convective heat transfer adequately with a relatively coarse mesh, which will save computational resources for later inclusion of radiative heat transfer effects to provide comprehensive CHT predictions.

Conjugate Heat Transfer Analysis of a Cooled Turbine Vane Using the V2F Turbulence Model

2006 ◽  
Vol 129 (4) ◽  
pp. 773-781 ◽  
Author(s):  
Jiang Luo ◽  
Eli H. Razinsky
Keyword(s):  
Heat Transfer ◽  
Turbulence Model ◽  
Conjugate Heat Transfer ◽  
Solid Metal ◽  
Operating Conditions ◽  
Metal Temperature ◽  
Heat Transfer Analysis ◽  
Turbulent Heat Transfer ◽  
Internal Cooling ◽  
Turbine Vane

The conjugate heat transfer methodology has been employed to predict the flow and thermal properties including the metal temperature of a NASA turbine vane at three operating conditions. The turbine vane was cooled internally by air flowing through ten round pipes. The conjugate heat transfer methodology allows a simultaneous solution of aerodynamics and heat transfer in the external hot gas and the internal cooling passages and conduction within the solid metal, eliminating the need for multiple/decoupled solutions in a typical industry design process. The model of about 3 million computational meshes includes the gas path and the internal cooling channels, comprising hexa cells, and the solid metal comprising hexa and prism cells. The predicted aerodynamic loadings were found to be in close agreement with the data for all the cases. The predicted metal temperature, external, and internal heat transfer distributions at the midspan compared well with the measurement. The differences in the heat transfer rates and metal temperature under different running conditions were also captured well. The V2F turbulence model has been compared with a low-Reynolds-number k-ε model and a nonlinear quadratic k-ε model. The V2F model is found to provide the closest agreement with the data, though it still has room for improvement in predicting the boundary layer transition and turbulent heat transfer, especially on the suction side. The overall results are quite encouraging and indicate that conjugate heat transfer simulation with proper turbulence closure has the potential to become a viable tool in turbine heat transfer analysis and cooling design.

Conjugate Heat Transfer Analysis of Internally Cooled Turbine Blade

2012 ◽  
Author(s):  
Ilhan Gorgulu ◽  
Baris Gumusel ◽  
I. Sinan Akmandor
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Turbulence Model ◽  
Conjugate Heat Transfer ◽  
Turbulence Models ◽  
Heat Transfer Analysis ◽  
Internal Cooling ◽  
Turbine Blade Cooling ◽  
Internally Cooled ◽  
Rib Turbulators

There are different characters of air flow in a conventional gas turbine blade cooling channel. These flow characters; including high streamline curvature caused from 180 degree bends, sequential flow separations caused from rib turbulators and pin-fin structures are analyzed separately with available commercial software for different turbulence models and validated against reliable experimental data from open literature. Also coupled conjugate heat transfer analyses on NASA C3X vane, which has only radial holes through blade span for cooling, are conducted with the same turbulence models. The accuracy information gathered from all these analyses; each interested with a single character of air and coupled conjugate heat transfer are put together and applied to a conjugate numerical analysis of internally cooled (VKI) LS-89 turbine blade. Internal cooling scheme which is applied to (VKI) LS-89 turbine blade encompassed the aforementioned flow characters and analyses are performed under realistic conditions. Because of the high temperature values occurring at realistic conditions, thermal conductivity and specific heat capacity of air and metal (Inconel 718) are modeled as temperature dependent material properties instead of using constant values. Conducted research revealed that 4 eqn. V2-f turbulence model gives similar results compared to the 2 eqn. Realizable k-e, k-w SST turbulence models for 180 degree bend and rib turbulator cases. However, at NASA C3X vane analyses V2-f turbulence model results are far more accurate than other two turbulence models in the manner of heat transfer coefficient and surface temperature distribution.

Application of Conjugate Heat Transfer in Multidisciplinary Design Optimization of Internal-Cooled Turbine Blade

2013 ◽  
Vol 423-426 ◽  
pp. 1693-1699
Author(s):  
Sheng Zhong Xu ◽  
Xiang Jun Fang ◽  
Zhao Yin
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Design Optimization ◽  
Turbulence Model ◽  
Multidisciplinary Design Optimization ◽  
Conjugate Heat Transfer ◽  
Multidisciplinary Design ◽  
Maximum Temperature ◽  
Cooling Effectiveness ◽  
Cooling Flow

The genetic algorithm was employed to Multidisciplinary Design Optimization of transonic internally cooled turbine blades based on the conjugate heat transfer (CHT) method. Firstly, a parametric modeling method was employed to model the internal-cooled blade.Comparison of the SST turbulence model with and withoutγ-θtransition model was conducted, and the influence and reason between turbulent region and heat transfer distribution was analyzed.The result shows that separation appeared after middle region of the suction surface, because of the pressure after shock wave decrease abruptly that reduce adverse pressure gradient resistance capacity of laminar flow, it leads to instability and transition, and then enter a state of turbulence, same to the heat transfer coefficient with the phenomenon of abrupt increase that impact the temperature distribution, consequently SST model with γ-θ transition is better to showcase the change of aerodynamic and heat transfer in the transition region; Then,comparing the cooling effectiveness with different number cooling holes of internal-cooled blade , four cooling channels case was the best choice in consideration of the cooling effectiveness and the manufacturing process and the cost of the blade; In the end, Automatic optimization process was set up ,andseveral optimization frameworks were achieved. With the cooling flow increase in 0.011849 kg/s, average temperature and maximum temperature were reduced by 4.92% and 1.55% respectively in the boundary conditionsoptimization, in addition to optimized the cooling flow and the cooling effectiveness, temperature distribution in the part of contrastive analysis of turbulence model was verifiable, Simultaneously it is important guiding significance for the geometry parameters optimization.

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