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A Review of Heat Transfer Enhancement through Flow Disruption in a Microchannel

Journal of Thermal Science 2015年第3期24卷 203-214页

作者： anupam dewan Pankaj Srivastava Department of Applied Mechanics Indian Institute of Technology Delhi Hauz Khas New Delhi - 110016 India Instruments R & D Establishment Defence R & D Organisation Dehradun (UK) - 248008 India

In this paper a comprehensive review of heat transfer enhancement through microchannels has been presented. Over the past few years due to multifunetion, shrinking package size and high power dissipation, the heat flux per unit area has increased significantly. Microchannels, with their large heat transfer surface to volume ratio and their small volumes, have shown a good thermal performance. Microchannels have been proven to be a high per- formaace cooling technique which is able to dissipate heat flux effectively from localized hot spots over small surface area. A good amount of heat transfer augmentation techniques have been reported on flow disruption through microchannel. These techniques promote free stream separation at the leading edge which results in boundary layer development and enhanced mixing leading to increased heat transfer. Flow disruption can be achieved through passive surface modifications, such as, shape of channel, dimple surfaces, ribs, cavities, groove structures, porous medium, etc. Combined effects of these geometrical configurations in heat transfer augmenta- tion are also reported in the literature. In this paper recent developments in experimental and numerical simula- tions of single-phase liquid cooled microchannel have been discussed to analyze the pressure drop, friction and heat transfer characteristics due to different flow conditions, roughness structure and passive surface modifica- tions. It has been observed that the flow disruption techniques are effective for heat transfer enhancement with lower penalties of increased pressure drop. The review concludes with suggestions for future research in this area.

关键词： Microchannel heat transfer enhancement boundary-layer pressure drop dimple surface cavitiesand ribs

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AN INVESTIGATION OF TURBULENT RECTANGULAR JET DISCHARGED INTO A NARROW CHANNEL WEAK CROSSFLOW

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Journal of Hydrodynamics 2008年第2期20卷 154-163页

作者： PATHAK Manabendra DASS Anoop K. dewan anupam Department of Mechanical Engineering Indian Institute of Technology Guwahati Guwahati - 781039 India

A computational investigation of the mean flow field of turbulent rectangular jets issuing into a narrow channel crossflow is presented. The length of the jet slot spans more than 55% of the crossflow channel bed, leaving a small clearance between the jet edge and sidewalls. A finite volume code employing the standard k-εmodel is used to predict the mean, three-dimensional flow field. The mean flow field is investigated for two velocity ratios （6 and 9）. Important flow features, such as the formation of different vortical structures and their characteristics owing to different values of the velocity ratio, are discussed. Some predicted results are compared with the experimental data reported in the literature. The predicted mean and turbulent flow properties are shown to be in good agreement with the experimental data.

关键词： turbulent jet crossflow narrow charmel velocity ratio vortices

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A MULTIGRID-ACCELERATED THREE-DIMENSIONAL TRANSIENT-FLOW CODE AND ITS APPLICATION TO A NEW TEST PROBLEM

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Journal of Hydrodynamics 2010年第6期22卷 838-846页

作者： KUMAR D.Santhosh DASS Anoop K. dewan anupam School of Mechanical and Building Science Vellore Institute of TechnologyVellore-632014India Department of Mechanical Engineering Indian Institute of Technology GuwahatiGuwahati-781039India Department of Applied Mechanics Indian Institute of Technology Delhi Hauz KhasNew Delhi-110016India

A multigrid-assisted solver tbr the three-dimensional time-dependent incompressible Navier-Stokes equations on graded Cartesian meshes is developed. The spatial accuracy is third-order for the convective terms and fourth-order for the viscous terms, and a fractional-step strategy ensures second-order time accuracy. To achieve good time-wise efficiency a multigrid technique is used to solve the highly time-consuming pressure-Poisson equation that requires to be solved at every time step. The speed-up achieved by multigrid is shown in tabular form. The performance and accuracy of the code are first ascertained by computing the flow in a single-sided lid-driven cubic cavity with good grid-economy and comparing the results available in the literature. The code, thus validated, is then applied to a new test problem we propose and various transient and asymptotically obtained steady-state results are presented. Given the care taken to establish the credibility of the code and the good spatio-temporal accuracy of the discretization, these results are accurate and may be used for ascertaining the performance of any computational algorithm applied to this test problem.

关键词： incompressible flows three-dimensional cavity flow fractional-step method multigrid method Taylor-Gorier-Like (TGL) vortices grid transformation

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Performance Optimization of a Six-Strand Tundish

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World Journal of Mechanics 2013年第3期3卷 184-193页

作者： Siddharth Gupta anupam dewan Department of Applied Mechanics Indian Institute of Technology Delhi New Delhi India

The aims of the present study are to predict and improve inclusion separation capacity of a six strand tundish by employing flow modifiers (dams and weirs) and to assess the influence of inclusion properties (diameter and density) together with velocity of liquid steel at the inlet gate on the inclusion removal efficiency of a six-strand tundish. Computational solutions of the Reynolds-Averaged Navier-Strokes (RANS) equations together with the energy equation are performed to obtain the steady, three-dimensional velocity and temperature fields using the standard k-ε model of turbulence. These flow fields are then used to predict the inclusion sepapration by numerically solving the inclusion transport equation. To account for the effects of turbulence on particle paths a discrete random walk model is employed. It was observed that with the employment of flow modifiers, the inclusion separation capacity of tundish increases without any large variation in the outlet temperatures. It is shown that inclusion properties and velocity are important parameters in defining the operating conditions of a six-strand tundish.

关键词： Tundish Inclusion Removal CFD Euler-Lagrangian Approach Turbulence Modeling

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