脉动流与波纹壁通道耦合强化换热及优化研究

Research on Coupling of Pulsating Flow and Corrugated Channels for Heat Transfer Enhancement and Genetic Algorithm Optimization

为获得节能效果良好的散热通道,并进一步提升壁面结构优化设计效率,提出将遗传算法应用于数值计算过程,建立壁面型线的数学模型。对比分析了正弦脉动流作用下弧型、正弦型和贝塞尔曲线型3类波纹壁通道内流动换热现象,实现应用遗传算法调控优化计算流程,完成了通道结构的精确、快速优化。结果表明,弧型通道的流阻最低,正弦型通道的传热增强效果最好,而贝塞尔型通道兼具适度的传热增强和流动阻力提升。当雷诺数为5000和10000时,贝塞尔型通道综合性能显著优于其余两类通道,相对提升均超过20%,而雷诺数增加到20000时,通道综合性能也仅略小于弧型通道。壁面结构的添加在近壁面处激发出高湍动能区域,增强了近壁面流体与主流的传热、传质过程,近壁面高温工质被周期性地输运向主流方向。以贝塞尔型通道为优化对象,以综合性能评价指标为目标函数,建立了结合遗传算法的壁面型线快速精确优化方法。优化后的贝塞尔型结构整体趋向右后方布置,抑制了背流侧次级涡的分裂,涡结构强度得到保证。这一现象改善了背流侧的温度分布,缓解了局部过热问题,并最终实现了综合性能评价指标高达38.7%的提升。

In order to obtain the channel enhanced heat transfer technology with good energy saving effect,the enhanced heat transfer performance mechanism and flow characteristics under the coupling effect of the corrugated channel wall profile and the inlet pulsating flow were studied.The flow and heat transfer phenomena in three kinds of corrugated channels under the sinusoidal pulsating flow were compared and analyzed.The results show that under the studied Reynolds number range,the arc channel has the lowest flow resistance,the sinusoidal channel has the best heat transfer enhancement effect,and the Bezier channel has both moderate heat transfer enhancement and flow resistance improvement.When the Reynolds number is 5000 or 10000,the comprehensive performance of the Bezier channel is significantly better than that of the other two kinds of channels,relatively improved by more than 20%.When the Reynolds number increases to 20000,the comprehensive performance is only slightly smaller than that of the arc channel.The addition of the wall structure excites a high turbulent kinetic energy region near the wall,which enhances the heat and mass transfer between the fluid near the wall and the mainstream,and the high-temperature fluid near the wall is periodically transported to the mainstream.Furthermore,with the Bezier channel featuring excellent comprehensive performance selected and the comprehensive performance evaluation criterion chosen as the objective function,a fast and accurate optimization method of the wall profile based on the genetic algorithm is established.The optimization results show that the Bezier structure tends to be arranged to the right and rear is conducive to the improvement of comprehensive performance,and the improvement of the optimal channel reaches 38.7%.The change of the channel structure affects the distribution position and intensity of the secondary vortex,which further improves the temperature distribution on the downstream side and alleviates the problem of local overheating.