Conjugate Heat Transfer Analysis for Gas Turbine Film-Cooled Blade

Author(s):  
Kuo-San Ho ◽  
Jong S. Liu ◽  
Thomas Elliott ◽  
Bruno Aguilar

This paper presents results of a study of the conjugate heat transfer (CHT) to calculate the metal temperature for a film-cooled gas turbine blade. ANSYS CFX14.0 code was selected as the computational fluid dynamic (CFD) tool to perform the CHT simulation. The two-equation SST turbulence model with automatic wall treatment was employed. The main flow inlet and exit boundary conditions were deduced from a multi-blade-row CFD code, Fine/Turbo by NUMECA. A core engine test operated at the maximum power condition. Thermocouples were used to validate the blade metal temperature calculations. The blade temperature comparison between test data and CHT predictions was in good agreement except at the suction side near the leading edge region. The pressure, temperature and Mach number distributions for blade internal and external flows were presented and examined. The streamline contours of the film flows on the pressure side and suction side were plotted and used to visualize the cooling effectiveness. In order to evaluate the influence of the turbulence model, the thermal results of four additional turbulence models (SA, RNG, K-ε, and SST with transition control) were compared to the test data. The SST model is suggested to be the appropriate turbulence model for the film-cooled blade temperature calculation in this study.

Author(s):  
Kuo-San Ho ◽  
Christopher Urwiller ◽  
S. Murthy Konan ◽  
Jong S. Liu ◽  
Bruno Aguilar

This paper explores the conjugate heat transfer (CHT) numerical simulation approach to calculate the metal temperature for the gas turbine cooled stator. ANSYS CFX12.1 code was selected to be the computational fluid dynamic (CFD) tool to perform the CHT simulation. The 2-equation RNG k-ε turbulence model with scalable modified wall function was employed. A full engine test with thermocouple measurement was performed and used to validate the CHT results. Metal temperatures calculated with the CHT model were compared to engine test data. The results demonstrated good agreement between test data and airfoil metal temperatures and cooling flow temperatures using the CHT model. However, the CHT calculations in the outer end wall had a discrepancy compared to the measured temperatures, which was due to the fact that the CHT model assumed an adiabatic wall as a boundary condition. This paper presents a process to calculate convection heat transfer coefficient (HTC) for cooling passages and airfoil surfaces using CHT results. This process is possible because local wall heat flux and fluid temperatures are known. This approach assists in calibrating an in-house conduction thermal model for steady state and transient thermal analyses.


Author(s):  
Zhenfeng Wang ◽  
Peigang Yan ◽  
Hongyan Huang ◽  
Wanjin Han

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.


Author(s):  
Takeshi Horiuchi ◽  
Tomoki Taniguchi ◽  
Ryozo Tanaka ◽  
Masanori Ryu ◽  
Masahide Kazari

In this paper, the Conjugate Heat Transfer (CHT) analysis, which utilizes commercial software STAR-CCM+ with detailed models and practical mesh size, was performed to the first stage cooled turbine airfoils for an industrial gas turbine produced by Kawasaki Heavy Industries, Ltd. (KHI). First its estimation accuracy was evaluated by comparing with the measurement results obtained with thermal index paint (TIP) and a pyrometer. After the validation of the CHT analysis, the metal temperature distribution was understood with the flow phenomena associated with it from the analysis results. To the parts where the metal temperature is locally high, then, the improvements of the cooling performance were considered with the CHT analysis and their effects were finally confirmed by measuring the metal temperature in the actual engine. The investigation reveals that the CHT analysis, which is validated with measurement results, makes it possible for cooling designers to efficiently improve the cooling performance of turbine airfoils with the adequate estimation accuracy, thus enhancing their durability for the reliability of gas turbines.


Author(s):  
Kuo-San Ho ◽  
Christopher Urwiller ◽  
S. Murthy Konan ◽  
Jong S. Liu ◽  
Bruno Aguilar

This paper explores the conjugate heat transfer (CHT) numerical simulation approach to calculate the metal temperature for a cooled gas turbine blade. ANSYS CFX14.0 code was selected as the computational fluid dynamic (CFD) tool to perform the CHT simulation. The two-equation SST turbulence model with automatic wall treatment was employed. A full engine test with Silicon Carbide (SiC) chip measurements was performed and used to validate the CHT results. Metal temperatures calculated with the CHT model were compared to engine test data. The results demonstrated good agreement between predicted and measured airfoil metal temperatures. The blade cooling flow prediction was matched to the flow network analysis. This paper describes a process to calculate convection heat transfer coefficients (HTC) for cooling passages and airfoil surfaces using CHT results. This process was made possible because local wall heat flux and fluid temperatures were known. This approach assisted in calibrating an in-house conduction thermal model for steady state thermal analyses.


2006 ◽  
Vol 129 (4) ◽  
pp. 773-781 ◽  
Author(s):  
Jiang Luo ◽  
Eli H. Razinsky

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.


Author(s):  
Jiang Luo ◽  
Eli H. Razinsky

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 10 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 three 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 mid-span 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 non-linear 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.


Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2096
Author(s):  
Joon Ahn ◽  
Jeong Chul Song ◽  
Joon Sik Lee

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.


Author(s):  
Duccio Griffini ◽  
Massimiliano Insinna ◽  
Simone Salvadori ◽  
Francesco Martelli

A high-pressure vane equipped with a realistic film-cooling configuration has been studied. The vane is characterized by the presence of multiple rows of fan-shaped holes along pressure and suction side while the leading edge is protected by a showerhead system of cylindrical holes. Steady three-dimensional Reynolds-Averaged Navier-Stokes (RANS) simulations have been performed. A preliminary grid sensitivity analysis with uniform inlet flow has been used to quantify the effect of spatial discretization. Turbulence model has been assessed in comparison with available experimental data. The effects of the relative alignment between combustion chamber and high-pressure vanes are then investigated considering realistic inflow conditions in terms of hot spot and swirl. The inlet profiles used are derived from the EU-funded project TATEF2. Two different clocking positions are considered: the first one where hot spot and swirl core are aligned with passage and the second one where they are aligned with the leading edge. Comparisons between metal temperature distributions obtained from conjugate heat transfer simulations are performed evidencing the role of swirl in determining both the hot streak trajectory within the passage and the coolant redistribution. The leading edge aligned configuration is resulted to be the most problematic in terms of thermal load, leading to increased average and local vane temperature peaks on both suction side and pressure side with respect to the passage aligned case. A strong sensitivity of both injected coolant mass flow and heat removed by heat sink effect has also been highlighted for the showerhead cooling system.


Author(s):  
Zhenfeng Wang ◽  
Peigang Yan ◽  
Hongfei Tang ◽  
Hongyan Huang ◽  
Wanjin Han

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.


Author(s):  
Ron-Ho Ni ◽  
William Humber ◽  
George Fan ◽  
John P. Clark ◽  
Richard J. Anthony ◽  
...  

Conjugate heat transfer analysis was conducted on a 648 hole film cooled turbine vane using Code Leo and compared to experimental results obtained at the Air Force Research Laboratory Turbine Research Facility. An unstructured mesh with fully resolved film holes for both fluid and solid domains was used to conduct the conjugate heat transfer simulation on a desktop PC with eight cores. Initial heat flux and surface metal temperature predictions showed reasonable agreement with heat flux measurements but under prediction of surface metal temperature values. Root cause analysis was performed, leading to two refinements. First, a thermal barrier coating layer was introduced into the analysis to account for the insulating properties of the Kapton layer used for the heat flux gauges. Second, inlet boundary conditions were updated to more accurately reflect rig measurement conditions. The resulting surface metal temperature predictions showed excellent agreement relative to measured results (+/− 5 degrees K).


Sign in / Sign up

Export Citation Format

Share Document