scholarly journals Experimental Study and Conjugate Heat Transfer Simulation of Turbulent Flow in a 90° Curved Square Pipe

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 94
Author(s):  
Guanming Guo ◽  
Masaya Kamigaki ◽  
Qiwei Zhang ◽  
Yuuya Inoue ◽  
Keiya Nishida ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Turbulent Flow ◽  
Cross Section ◽  
Conjugate Heat Transfer ◽  
Air Flow ◽  
Temperature Fields ◽  
Spatial Average ◽  
Flow And Heat Transfer ◽  
Curved Pipes

This paper discusses the turbulent flow and heat transfer from a uniform air flow with high temperature to the outside through a 90° curved square pipe. Both conjugate heat transfer (CHT) simulation and experiments of temperature field measurements at cross sections of the pipe are performed. A straight pipe is investigated and compared with the 90° curved pipe. The temperature of the air flow at the inlet of the pipe is set at 402 K, and the corresponding Reynolds number is approximately 6 × 104. To obtain the spatial average temperature at each cross section, the temperature fields are measured along the streamwise of the pipes and in the circumferential direction using thermocouples at each cross section from the inlet to the outlet of both the straight and curved pipes. Furthermore, the simulation is performed for turbulent flow and heat transfer inside the pipe wall using the Re-normalization group (RNG) k-ε turbulence model and CHT method. Both the experimental and numerical results show that the curvature of the pipe result in a deviation and impingement in the high-temperature core and a separation between the wall and air, resulting in a secondary flow pattern of the temperature distribution.

Influence Of Relative Size Of The U-Shaped Silicon Rod On Conjugate Heat Transfer In The Regime Of Gas Buayancy Induced Convection

2015 ◽  
Vol 10 (3) ◽  
pp. 76-88
Author(s):  
Vladimir Berdnikov ◽  
Konstantin Mitin ◽  
Alina Mitina
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Solid Body ◽  
Conjugate Heat Transfer ◽  
Relative Size ◽  
Three Dimensional ◽  
Boussinesq Approximation ◽  
Temperature Fields ◽  
Spatial Form ◽  
Section Size

The influence of relative cross-section size of an electrically heated U-shaped silicon rod which is placed in a gas-filled rectangle container with isothermal cold walls on conjugate heat transfer in the regime of buoyancy induced convection was numerically studied in three-dimensional formulation. The natural convection equations in the Boussinesq approximation in term temperature, velocity vortex and velocity vector potential were solved by the finite element method. The spatial form of convective flow and temperature fields in liquid and solid body were studied. It was show that spatial form and intensity of convective flows is significantly depends on the cross-section size of U-shaped silicon rod. This is has strong influence on the temperature field in a solid body.

scholarly journals Numerical Computation of Turbulent Flow and Heat Transfer in a Radially Rotating Channel with Wall Conduction

2001 ◽  
Vol 7 (3) ◽  
pp. 209-222
Author(s):  
Frank K. T. Lin ◽  
G. J. Hwang ◽  
S.-C. Wong ◽  
C. Y. Soong
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Numerical Computation ◽  
Experimental Models ◽  
Temperature Fields ◽  
Navier Stokes ◽  
Turbine Blade Cooling ◽  
Flow And Heat Transfer ◽  
Energy Equations ◽  
Rotating Channel

This work is concerned with numerical computation of turbulent flow and heat transfer in experimental models of a radially rotating channel used for turbine blade cooling. Reynolds-averaged Navier-Stokes and energy equations with a two-layer turbulence model are employed as the computational model of the flow and temperature fields. The computations are carried out by the software package of “CFX-TASCflow”. Heat loss from the channel walls through heat conduction is considered. Results at various rotational conditions are obtained and compared with the baseline stationary cases. The influences of the channel rotation, through-flow, wall conduction and the channel extension on flow and heat transfer characteristics are explored. Comparisons of the present predictions and available experimental data are also presented.

Numerical Study of Pyrolysis Effects on Supercritical-Pressure Flow and Conjugate Heat Transfer of N-Decane in the Square Channel

2017 ◽  
Author(s):  
Xizhuo Hu ◽  
Zhi Tao ◽  
Jianqin Zhu ◽  
Haiwang Li
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Conjugate Heat Transfer ◽  
Supercritical Pressure ◽  
Operating Conditions ◽  
Strong Impact ◽  
Heat Absorption ◽  
Regenerative Cooling ◽  
Flow And Heat Transfer ◽  
Bottom Interface

Regenerative cooling has become the most effective and practical method of thermal protection to the high temperature structures of scramjet engines. Pyrolytic reactions of endothermic hydrocarbon fuel have significant influence on the regenerative cooling process at high temperature due to a large amount of heat absorption and fluid components change. In this paper, a three-dimensional (3D) model is developed for numerically investigating the flow and heat transfer of pyrolytic reacted n-decane in the square engine cooling channel under supercritical pressure with asymmetrical heating imposed on the bottom channel surface. The one-step global pyrolytic reaction mechanism consisting of 18 species is adopted to simulate the pyrolysis process of n-decane. The governing equations for species continuum, momentum, energy and the k-ω turbulence equation are properly solved, with accurate computations of the thermophysical and transport properties of fluid mixture, which undergo drastic variations and exert strong impact on fluid flow and heat transfer process in the channel. The numerical method is validated based on the good agreement between the current predictions and the experimental data. Numerical studies of the pyrolysis effects on the characteristics of flow resistance and conjugate heat transfer under various operating conditions have been conducted. Results reveal that pyrolysis intensively takes place in high temperature regions. The pressure drop along the channel steeply rise due to the further fluid acceleration caused by pyrolysis. It is found that the variations of heat flux at the bottom, top and side fluid-solid-interface walls are totally different. Pyrolysis could lead to greater heat transfer enhancement at the bottom interface, consequently, more heat is transferred into the fluid region through the bottom interface. The dual effects of heat absorption and enhanced heat transfer caused by pyrolysis produce strong influence on the wall temperature. The mechanism of these physicochemical phenomena are also analyzed in detail, which is conducive to fundamentally understand the complicated physicochemical process of regenerative cooling. The present work has profound significance for the development of regenerative cooling technology.

scholarly journals Flow and Heat Transfer Performances of Liquid Metal Based Microchannel Heat Sinks under High Temperature Conditions

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 95
Author(s):  
Tao Wu ◽  
Lizhi Wang ◽  
Yicun Tang ◽  
Chao Yin ◽  
Xiankai Li
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Liquid Metal ◽  
Cross Section ◽  
Great Influence ◽  
Heat Sinks ◽  
Working Fluid ◽  
Transfer Model ◽  
Flow And Heat Transfer ◽  
Microchannel Heat Sinks

Developments in applications such as rocket nozzles, miniature nuclear reactors and solar thermal generation pose high-density heat dissipation challenges. In these applications, a large amount heat must be removed in a limited space under high temperature. In order to handle this kind of cooling problem, this paper proposes liquid metal-based microchannel heat sinks. Using a numerical method, the flow and heat transfer performances of liquid metal-based heat sinks with different working fluid types, diverse microchannel cross-section shapes and various inlet velocities were studied. By solving the 3-D steady and conjugate heat transfer model, we found that among all the investigated cases, lithium and circle were the most appropriate choices for the working fluid and microchannel cross-section shape, respectively. Moreover, inlet velocity had a great influence on the flow and heat transfer performances. From 1 m/s to 9 m/s, the pressure drop increased as much as 65 times, and the heat transfer coefficient was enhanced by about 74.35%.

Turbulent Flow and Heat Transfer in a Symmetric Expansion Plane Channel

2005 ◽  
Author(s):  
Terukazu Ota ◽  
Takuma Suzuki ◽  
Hiroyuki Yoshikawa
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Large Scale ◽  
Plane Channel ◽  
Flow Region ◽  
Expansion Ratio ◽  
Open Circuit ◽  
Temperature Fields ◽  
Flow And Heat Transfer ◽  
Separated And Reattached Flow

Experimental results of turbulent flow and heat transfer in the separated and reattached flow in a symmetric expansion plane channel are presented. Experiments were conducted using a low speed open circuit wind tunnel, the expansion ratio of channel was 2.0 and the Reynolds number 15000, respectively. The flow and temperature fields were measured using split film probes and a cold wire. The conditional sampling techniques were employed in order to investigate the large scale vortex structure shed from the reattachment flow region and its correlation with the heat transfer behavior. It is found that the local Nusselt number profile is considerably different on the upper and lower walls due to the Coanda effect. Two large scale vortices shed from the reattachment regions on two walls are combined into one large vortex in the redeveloping region, whose configuration is estimated to be an ellipse inclined to the main flow.

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