涡旋核心分布对斜置肋片蒸汽冷却通道换热特性的影响

Effect of Vortex Core Distribution on Heat Transfer Performance in Steam-Cooled Channels with Inclined Ribs

数值计算了宽高比为2∶1,雷诺数为1×10^4~6×10^4,肋角度分别为30°、60°、90°时蒸汽冷却带肋通道,采用流场涡旋核心显示技术分析了各肋角度下带肋通道涡旋的产生、演变过程、形态变化以及分布规律,研究了涡旋分布规律对通道换热系数的影响。结果表明：肋角度对带肋通道涡旋形态和分布规律有较大影响,90°通道主要由横向涡组成,30°、60°通道主要由纵向涡和主涡组成;纵向涡的换热特性比横向涡更好,30°、60°通道平均换热系数比90°通道高;30°通道纵向涡的分支以及流体的黏性耗散会导致纵向涡涡旋强度和尺度减小、纵向涡的换热性能削弱,这使得30°通道平均换热系数比未发生纵向涡分支的60°通道低;相对于边界层的距离、涡旋半径,涡旋强度、涡旋核心是影响涡旋强化换热的更重要的参数。该结果可为主动控制带肋通道涡旋强化换热研究提供参考。

The steam-cooled channels with rib angles of 30°,60°and 90°,ducts aspect ratio 2∶1and Reynolds number ranging from 1×10^4 to 6×10^4 are numerically simulated.The vortex generation,evolution,morphological changes and its distribution are numerically analyzed with flow field vortex core technology and the effect of vortex distribution of ribbed channels on heat transfer performance are also investigated.The result indicates that morphology and distribution of vortex in ribbed channels strongly depend upon the rib angles.In 90°channels transverse vortex dominates,and in 30°and 60°channels longitudinal vortex and main vortex do;the average heat transfer coefficient in 30°and 60°channels is higher than that in 90°channel because of better heat transfer performance of longitudinal vortex than that of transverse vortex;the average heat transfer coefficient in 30°channel is lower than in 60°channel without bifurcated longitudinal vortex because the bifurcated longitudinal vortex in 30° channel and viscousdissipation of fluid result in the decreased strength and scale of the longitudinal vortex to weaken the heat transfer performance;the vortex strength,vortex core location relative to boundary layer and radius of vortex are all the important parameters for vortex heat transfer performance.