梯形断面水槽中横向扩散系数的实验

Experimental study on transverse diffusion coefficients in an open trapezoidal channel

为研究南水北调中线工程总干渠梯形断面明渠水流中污染物质混合输移,对斜边边坡分别为2.5:1和4:1的梯形断面水槽中物质的横向扩散系数进行了实验研究。采用粒子图像测速(PIV)技术和平面激光诱导荧光(PLIF)技术测量了水槽中水流的流场和污染物质扩散输移的浓度场,得到了梯形断面水槽中物质的横向扩散系数。研究表明:梯形断面水槽中的横向扩散系数是相应的矩形断面的1.2倍,污染物质进入水槽中所形成的污染带宽是矩形断面的1.1倍。

The transverse diffusion coefficient in an open trapezoidal channel with side gradients of 2.5∶1 or 4.0∶1 was measured experimentally to model pollutant mixing and transport in the open trapezoidal channels of the main canal of the SouthtoNorth Water Transfer Project. The water flow velocity and pollutant concentration distributions were measured by a particle image velocimeter (PIV) and planar laser induced fluorescence (PLIF) to calculate the transverse diffusion coefficient. The results show that the transverse diffusion coefficients in open trapezoidal channels are of 20% larger than the diffusion coefficients in rectanglar sections. The pollutant zone in the trapezoidal channel is of 10% larger than the zone in a rectanglar channel. 