矩形与收敛通道内高实度扰流柱换热特性研究

Study on heat transfer characteristics of high solidity pin fin arrays in constant and converging channels

采用SST k-ω湍流模型,对矩形与收敛两种通道内高实度(45%)圆形扰流柱的传热与流动特性进行数值模拟。通过比较两种通道内的流场结构,分析其内部冷却气体的流动机理,进而探求扰流柱阵列的传热性能与压降变化。结果表明:通道类型对内部流场结构有很大影响。收敛通道内流体的速度相比矩形通道的呈现沿程增加的趋势,其对自身的流动损失及换热效果影响加大;两种通道内扰流柱的平均换热水平随进口雷诺数的增大均呈指数上升趋势,相比较收敛通道的更高,但差距逐渐缩小;两种通道的整体压力损失系数均呈指数下降趋势。同一进口雷诺数下,矩形通道在中游出现换热峰值,收敛通道的换热效果沿流向持续提升,两者虽在相同排列产生换热波动点,但单排换热差距逐渐增大。矩形通道内单排扰流柱压力损失系数沿流向先降低后升高,收敛通道内则持续上升。

To investigate the heat transfer and flow characteristics in constant and converging channels,nu.merical simulation of the high solidity pin-fin arrays with SST k-ω turbulence model was carried out. The heattransfer and pressure drop performance in pin-fin arrays were explored through the analysis of the flow mecha.nism in two kinds of channels according to the comparison of the flow structure. The result shows that the typeof channel changing will impact a lot on internal cooling gas flow field structure. The flow velocity of constantchannel becomes faster along the channel, and affects more on pressure loss coefficient and the heat transfer.The heat transfer effect is exponentially enhanced with the increasing of the inlet Reynolds number in two kindsof cooling channel, while for converging channel is even higher, but the gap gradually gets narrow, and the pres.sure loss coefficient decreases exponentially in both channels. Under the same inlet Reynolds number, the peakvalue of heat transfer occurs in the middle region of the constant channel, the heat transfer of convergent chan.nel increases continuously along the flow direction. Although there is the same waved point about heat transfer,the gap between the two channels increases gradually. The pressure loss coefficient in the constant channel de.creases first and then increases, while in the converging channel it shows a continuously upward trend.