导流片对椭圆肋片通道传热与流动特性的影响

Effect of Deflector on Heat Transfer and Flow Characteristics of Elliptical Ribbed Channel

通过引入椭圆型的肋片作为扰流器,利用可实现的k-ε湍流模型对椭圆肋片通道以及设置导流片后通道内的传热和流动特性进行了数值模拟,并与传统凹槽通道内的传热特性作比较.结果表明:椭圆肋片通道内的传热系数比传统凹槽提高了2～3倍;随着椭圆肋片高度的增加,通道内的传热系数越来越大,同时压降也越来越大;引入导流片能提高椭圆肋片通道内的传热系数;在椭圆肋片最高点的下游位置引入圆弧型导流片后,传热系数比无导流片通道的传热系数提高了33%;导流片从肋片的最高点沿着肋片往下游移动,传热系数呈现先增大后下降的趋势,而压降则不断下降.综合比较发现,圆弧导流片在椭圆肋片下游段的0.9倍弧长位置时,通道的综合性能最好,而传热系数最大的位置是0.7倍弧长位置,导流片位置靠近椭圆肋片通道的流动分离点有利于强化传热.

In order to investigate the effects of turbulators on the heat transfer in ribbed channels,the heat transfer and flow characteristics of elliptical ribbed channels with and without deflector are numerically simulated by using a realizable k-ε turbulence model,and the results are compared with those of the traditional grooved channel.The results show that the heat transfer coefficient of elliptical ribbed channel is about 3-4 times that of the traditional grooved channel,that the heat transfer coefficient and the pressure drop both increase with the rib height,that the adoption of deflector remarkably raises the heat transfer coefficient,that the heat transfer coefficient of the ribbed channel with deflector mounted at the top of rib downstream is 33% higher than that of the channel without curved vanes,and that,with the movement of the deflector along the arc length of ribs,the heat transfer coefficient first increases and then decreases,while the pressure drop continuously decreases.Moreover,it is found from comprehensive comparison that the ribbed channel is of the highest comprehensive performance when the deflector are mounted at the location of 0.9 time arc length of the rib downstream,that the heat transfer coefficient reaches the maximum when the vanes are mounted at the location of 0.7 time arc length of the rib downstream,and that the nearness of the deflector for the flow separation point is favorable for the heat transfer enhancement.