涡流发生器对超临界CO_2传热和流阻性能影响的数值模拟研究

采用数值模拟方法,对布置有不同结构参数小尺度涡流发生器的矩形槽道内超临界流体的传热特性进行了研究。分析了涡流发生器所诱导的纵向涡对超临界流体传热影响的内在机理。结果表明,斜截半椭圆柱涡流发生器对超临界CO_2传热恶化现象具有明显的抑制效果,而对于超临界CO_2非传热恶化现象的影响并不明显。超临界CO_2发生传热恶化现象时,涡流发生器下游的局部壁面剪切应力与传热系数的变化趋势相同,传热恶化现象会造成壁面剪切应力显著增大。研究还发现,涡流发生器的结构参数对于超临界流体传热现象存在明显影响。

Numerical Simulation on Effect of Vortex Generator on Heat Transfer and Flow of Supercritical CO2

The heat transfer characteristics of supercritical fluid in a rectangular channel with small scale vortex generator of different parameters were numerically investigated.The effects of span-wise vortices produced by vortex generator on heat transfer of supercritical fluid were analyzed.The results show that the angle-cut elliptical column vortex generator can suppress the heat transfer deterioration of supercritical fluid,while it has little effect on the no-deteriorated heat transfer of supercritical fluid.The local wall shear stress and heat transfer coefficient at the downstream of the vortex generator exhibit similar tendencies when heat transfer deterioration occurs.However,heat transfer deterioration phenomenon would intensify the wall shear stress.It could also be observed that the configurations of vortex generator could greatly influence the characteristics of heat transfer of supercritical fluid.