Effects of turbulator shape,inclined magnetic field,and mixed convection nanofluid flow on thermal performance of micro-scale inclined forward-facing step  

湍流器形状、倾斜磁场和混合对流纳米流体流动对微尺度倾斜前向台阶热性能的影响

作　　者：E.JALIL G.R.MOLAEIMANESH 

机构地区：[1]Research Laboratory of Automotive Fluids and Structures Analysis,School of Automotive Engineering,Iran University of Science and Technology,Tehran 16846-13114,Iran

出　　处：《Journal of Central South University》2021年第11期3310-3326,共17页中南大学学报（英文版）

摘　　要：This investigation numerically examined the combined impacts of different turbulator shapes,Al_(2)O_(3)/water nanofluid,and inclined magnetic field on the thermal behavior of micro-scale inclined forward-facing step(MSIFFS).The length and height for all turbulators were considered 0.0979 and 0.5 mm,respectively,and the Reynolds number varied from 5000 to 10000.In order to compare the skin friction coefficient(SFC) and the heat transfer rate(HTR)simultaneously,the thermal performance factor parameter(TPF) was selected.The results show that all considered cases equipped with turbulators were thermodynamically more advantageous over the simple MSIFFS.Besides,using Al_(2)O_(3)/water nanofluid with different nanoparticles volume fractions(NVF) in the presence of inclined magnetic field(IMF)increased HTR.With an increment of NVF from 1% to 4% and magnetic field density(MFD) from 0.002 to 0.008 T,HTR and subsequently TPF improved.The best result was observed for MSIFFS equipped with a trapezoidal-shaped turbulator with 4% Al_(2)O_(3) in the presence of IMF(B=0.008 T).The TPF increased with the augmentation of Re,and the maximum value of it was 5.2366 for MSIFFS equipped with a trapezoidal-shaped turbulator with 4% Al_(2)O_(3),B=0.008 T,and Re=10000.本研究数值研究了不同湍流器形状、Al_(2)O_(3)/水纳米流体和倾斜磁场对微尺度倾斜前向台阶(MSIFFS)热行为的综合影响。湍流器的长度和高度分别为0.0979和0.5 mm,雷诺数为5000到10000。为了同时比较表面摩擦因数(SFC)和传热率(HTR),选择热性能因子(TPF)为评估参数。结果表明,配备湍流器的MSIFFS比简单的MSIFFS在热力学上更有优势。此外,在加载倾斜磁场(IMF)情况下,使用具有不同纳米粒子体积分数(NVF)的Al_(2)O_(3)/水纳米流体增加了HTR,当NVF从1%增加到4%,磁场密度(MFD)从0.002 T增加到0.008 T时,HTR和TPF均有所提高。在加载IMF(B=0.008 T)的情况下,含有4%Al_(2)O_(3)纳米流体的梯形湍流器可得到最佳性能。TPF随着Re的增加而增加,对于含有4%Al_(2)O_(3)纳米流体,在B=0.008 T,Re=10000的梯形湍流器的MSIFFS,其最大值为5.2366。

关 键 词：microchannel forward-facing step TURBULATOR inclined magnetic field heat transfer enhancement 

分 类 号：O357.5[理学—流体力学] TB383.1[理学—力学]