三角形通道内对称三角翼的脉动传热特性

Heat Transfer Enhancement of Pulsating Flow in Triangular Ducts Fitted with Symmetrical Delta Wings

该文研究了三角形管道内加入对称三角翼扰流元件在脉动流作用下的对流换热特性,工质是体积分数为1%的Water-SiO2纳米流体,雷诺数为500~1 600,利用CFD软件进行数值仿真。结果表明,当雷诺数和振幅定常时,即当雷诺数为1 500,振幅为0.75时,脉动流作用下存在强化与弱化换热的临界频率约为1 Hz。当临界频率大于1 Hz时,强化换热,反之则会弱化换热。当频率为10 Hz时,换热最大增强了3%;当频率为0.001 Hz时,换热最大弱化了5%。同时利用场协同原理研究了传热机理,结果表明场协同角越小,换热效果越好,并且距离三角翼片下游越近,场协同角越小。当振幅为0.75,频率为10 Hz,雷诺数为1 500时在一个周期内的平均场协同角最小,换热效果最好。

The heat transfer in the triangular ducts fitted with symmetric delta wings disturbance flow components is studied in pulsating flow using CFD software. The refrigerant is Water-SiO2 nanofluid. The range of Reynolds number is 500~1 600. The results show that when the Reynolds number is 1 500 and amplitude is 0.75, there exists a critical frequency which is the flex spot between enhanced and weakened heat transfer with the pulsating conditions. The critical frequency is about 1 Hz. When the frequency is higher than 1 Hz, heat transfer is enhanced. However, when the frequency is lower than 1 Hz, which the heat transfer weakend. When the frequency is 10 Hz, the maximum heat transfer enhancement is 4%.When the frequency is 0.001 Hz, the maximum weakening of the heat transfer is 3%. The heat transfer mechanism is studied by using the field synergy principle. The smaller the field synergy angle is, the better the heat transfer effect is. The closer the distance from the delta wing is, the smaller the field synergy angle is. It can be observed that the average field synergy angle for Re=1 500, Au=0.75 and f=10 is the smallest, and the enhanced heat transfer is the best.