梯形和矩形通道内短扰流柱排流动与换热计算

Numerical simulation on heat transfer and pressure drop in pin-fin trapezoidal and rectangular duct

关键词:  涡轮叶片  短扰流柱排+  传热  落压比  数值计算

Key words:  Turbine blade  Short pin-fin array~+  Heat transfer  Blow-down ratio  Numerical calculation

摘要:

为了得到逐渐收缩的梯形通道内扰流柱排的流动换热的规律,对梯形通道内扰流柱排的端壁换热和压力损失进行了数值计算,并与矩形通道进行比较。计算结果表明:(1)梯形通道与矩形通道的端壁总平均换热系数相差不大,但是梯形通道内每排扰流柱的Nu数相差较大。(2)相同来流Re数条件下,梯形通道的压力损失系数远大于矩形通道。所以,在实际计算逐渐收缩的梯形通道内扰流柱排的平均换热时,可近似采用矩形通道内扰流柱的实验关联式,并且将每排扰流柱分别计算。在计算压力损失时,不能将梯形通道近似成矩形通道。

Abstract:

A numerical study was performed to investigate the heat transfer and pressure drop characteristics in trapezoidal duct with pin-fin arrays. Comparisons were made between trapezoidal and rectangular ducts. It is found that in the trapezoidal duct, low velocity zone behind each pin is smaller and the endwall heat transfer distribution is different from rectangular duct because of the effect of the accelerating flow through the convergent passage. While the overall heat transfer in the trapezoidal duct is similar to the rectangular duct, the row average heat transfer is gradually increased along the streamwise direction, and the average Nusselt number of the first row is much lower than that of the last row. The results also show that for a fixed Reynolds number the overall pressure drop in the trapezoidal duct is much higher than that in the rectangular duct.