Non-linear Non-Iterative transient inverse conjugate heat transfer method applied to microelectronics

Recent development in commercial CFD codes offers possibilities to include the solid body in order to perform conjugate heat transfer computations for complex geometries. The current paper aims to analyse the differences between a conjugate heat transfer computation and conventional uncoupled approaches where a heat transfer coefficient is first derived from a flow solution and then taken as boundary condition for a thermal conduction analysis of the solid part. Whereas the thermal analyses are done with a Rolls-Royce in-house finite element code, the CFD as well as the conjugate heat transfer computation are done using the new version 8 of the commercial code Fine Turbo from Numeca International. The analysed geometry is a turbine cascade that was tested by VKI in Brussels within the European FP6 project AITEB 2. First, the paper presents the aerodynamic results. The pure flow solutions are validated against pressure measurements of the cascade test. Then, the heat transfer from flow computations with wall temperature boundary conditions is compared to the measured heat transfer. Once validated, the heat transfer coefficients are used as boundary condition for three uncoupled thermal analyses of the blade to predict its surface temperatures in a steady state. The results are then compared to a conjugate heat transfer method. Therefore, a mesh of the solid blade was added to the validated flow computation. The paper will present and compare the results of conventional uncoupled thermal analyses with different strategies for the wall boundary condition to results of a conjugate heat transfer computation. As it turns out, the global results are similar but especially the over-tip region with its complex geometry and flow structure and where effective cooling is crucial shows remarkable differences because the conjugate heat transfer solution predicts lower blade tip temperatures. This will be explained by the missing coupling between the fluid and the solid domain.

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Conjugate Heat Transfer Simulation of the Intercooled Compressor Vanes Based on Discontinuous Galerkin Method

Volume 5A: Heat Transfer ◽

10.1115/gt2016-56930 ◽

2016 ◽

Author(s):

Long-gang Liu ◽

Chun-wei Gu ◽

Xiao-dong Ren

Keyword(s):

Heat Transfer ◽

Discontinuous Galerkin ◽

Gas Turbines ◽

Conjugate Heat Transfer ◽

Main Stream ◽

Two Dimensional ◽

Convective Cooling ◽

Cooling Channels ◽

Transfer Method ◽

Aero Engines

Convective cooling channels are applied in a two-dimensional compressor vane to use the intercooling method to improve the efficiency of Brayton cycle and reduce the temperature of the vane. In this paper, we analyze the effect of coolant to the aerodynamic performance and heat transfer performance of the main stream and the vane. For the case of a two-dimensional compressor vane NACA65-(12A2I8b)10, the vane which has five convective cooling channels has been numerically simulated in different test conditions by discontinuous Galerkin (DG) method. The coolant is supercritical carbon dioxide whose pressure is 10MPa. Conjugate heat transfer method has been used in this paper. The numerical simulation result is similar to the experiment data and has been compared with the result of the vane without cooling channels to prove the effect of cooling channels. Cooling channels have large effect on the distribution of temperature and heat transfer coefficient. In addition, the relationship between Nu and Re on the fluid-solid interface has been analyzed and a suitable empirical equation has been obtained. This work analyzes the effect of intercooling system in the compressor and give several advice on future engineering applications in aero engines and gas turbines.

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Non-linear drag induced entropy generation analysis in a microporous channel: The effect of conjugate heat transfer

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2017.01.041 ◽

2017 ◽

Vol 108 ◽

pp. 2217-2228 ◽

Cited By ~ 9

Author(s):

Harshad Sanjay Gaikwad ◽

Pranab Kumar Mondal ◽

Somchai Wongwises

Keyword(s):

Heat Transfer ◽

Entropy Generation ◽

Conjugate Heat Transfer ◽

Non Linear ◽

Linear Drag

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Research on Aerodynamic Characteristics of Air-Cooled Turbine Blade with Conjugate Heat Transfer Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.732-733.270 ◽

2013 ◽

Vol 732-733 ◽

pp. 270-275

Author(s):

Jing Jing Zhang ◽

Lian Fu Wang ◽

Xiang Jun Fang

Keyword(s):

Heat Transfer ◽

Turbine Blade ◽

Conjugate Heat Transfer ◽

Air Flow ◽

Aerodynamic Characteristics ◽

Cooling Effect ◽

Inlet Temperature ◽

Turbine Inlet Temperature ◽

Transfer Method ◽

Aero Engines

In order to improve the performance of aero engines, trying to increase the turbine inlet temperature is an important way. But the turbine inlet temperature of modern aero engines can be more than 2000 K, which is far more than what the materials can bear. So advanced cooling technologies should be introduced to solve this problem. Using the conjugate heat transfer method, this paper researched the aerodynamic characteristics of a certain turbine blade with complex cooling structures. Some conclusions can be drawn: the velocity of the air flow and different distributions of coolant flow for turbine blade with multiple cooling air inlets have great influence on the cooling effect; the cooling effect decreases as the temperature ratio decreases; with the same mass cold gas, the less film cooling holes, the worse cooling effect; therefore, a reasonable air flow distribution plays an important role in obtaining good cooling effect.

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A new conjugate heat transfer method to analyse a 3D steam cooled gas turbine blade with temperature-dependent material properties

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406211418734 ◽

2011 ◽

Vol 226 (5) ◽

pp. 1309-1320 ◽

Cited By ~ 11

Author(s):

M M Jafari ◽

G Atefi ◽

J Khalesi ◽

A Soleymani

Keyword(s):

Heat Transfer ◽

Gas Turbine ◽

Turbine Blade ◽

Power Plants ◽

Conjugate Heat Transfer ◽

Three Dimensional ◽

Computer Code ◽

Gas Turbine Blade ◽

Temperature Dependent ◽

Transfer Method

The erosion of the hot regions in a gas turbine is one of the most important challenges encountered by the power plants. Though several numerical simulations of the problem have been reported so far, little is known to give accurate results. In this article, the thermoelastic behaviour of a gas turbine blade with internal steam-cooled channels positioned within a three-dimensional cascade configuration has been studied. A computer code based on the conjugate heat transfer method using the simultaneous solution of Navier–Stokes and heat transfer equations has been developed. From this study, the temperature distribution along with the stress values at high temperatures has been obtained. The blade parameters such as E, α, and K were considered to be a function of the temperature. In the previous works, usually only one or two of these parameters was considered as temperature dependent and the others constant. In this article, all the blade parameters, though making the equations highly non-linear, were considered as a function of temperature. The results have been compared with the available experimental data and a good agreement is observed. According to these findings, taking the temperature dependency of materials into account increases the estimations accuracy and brings the results closer to the reality.

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Application of Non-Linear Krylov Solvers for Conjugate Heat Transfer Simulations of Electrical Battery Packs

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4051372 ◽

2021 ◽

pp. 1-33

Author(s):

Parvez Sukheswalla ◽

Raju Mandhapati ◽

Chu Wang ◽

Nitesh Attal ◽

Kislaya Srivastava

Keyword(s):

Heat Transfer ◽

Fixed Point ◽

Lithium Ion Battery ◽

Conjugate Heat Transfer ◽

Energy Equation ◽

Computational Cost ◽

Lithium Ion ◽

Battery Pack ◽

Anisotropic Thermal Conductivity ◽

Non Linear

Abstract Krylov-based methods are an attractive alternative to traditional fixed-point iterative schemes, being much more robust and accurate when solving elliptic equations (e.g., the energy equation in the solid domain). This study assesses the performance of a Krylov-based accelerator, when used for Conjugate Heat Transfer (CHT) simulations of an electrical battery-pack. The non-linear nature of CHT simulations (due to spatial & temporal changes in boundary conditions) necessitates the use of the non-linear form of the Krylov-based accelerator (termed NKA). NKA is used while performing steady-state CHT simulations of an air-cooled Lithium-ion battery-pack, specifically to help accelerate the solution of the solid-domain energy equation. The effect of using either isotropic or anisotropic thermal conductivity within the cylindrical Lithium-ion battery cells is also evaluated. Results obtained using the NKA accelerator are compared, in terms of accuracy and speed, to those obtained from a traditional non-linear fixed-point iterative scheme based on Successive Over-Relaxation (SOR). The NKA accelerator is found to perform quite well for the problem at hand, providing results with the specified accuracy, while also being between 5 and 20 times faster than SOR (while solving the solid energy equation). The robust nature of NKA also leads to better global heat-balance within the battery-pack at all times during the simulation. Overall, computational cost reductions of 30% to 40% are observed when using NKA for the battery-pack simulations.

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