小型高速水洞收缩段的优化设计

Optimized design of the contraction in a minitype high-speed water-tunnel

简要介绍了小型高速水洞收缩段设计的原则,收集对比了几种典型的收缩曲线。利用商业化的计算流体动力学软件—Fluent,结合实例,采用二维轴对称模型对收缩段的长度进行了选择,对不同收缩曲线型面的流场品质进行了对比分析:优化的三次曲线(n=7、xm=0.4)或Batchelor-Shaw曲线的出口流场均匀性较好,移轴的Witozinsky曲线出口湍流度较小,五次方曲线进出口损失水头较小;采用三维对称模型简单模拟了矩形截面的情况,结果显示其出口截面上的流速和压力等值线近似呈圆形,沿轴向进口和出口附近壁面会出现流速的降低和过冲,角部附近速度分布严重不均匀。

The principle of the design of the water-tunnel contraction is introduced,several typical contraction curves provided by former researchers are collected and compared.Using commercial Computational Fluid Dynamics （CFD） software-Fluent,the length of contraction is chose, the flied quality of different contraction curves using a 2-D axial symmetric k-ε model is compared and some suggestions on the selection of the curves to different requirement are made. The uniformity of the flow field is a little better of the improved 3-power curve and Batchelor-Shaw curve;the Witozinsky curve has a property of lower turbulent intensity; and the head loss of 5-power curve is lower. Using a 3-D symmetric k-ε model, the rectangular case is considered. The results show that the pressure and velocity isolines are nearly circular on the outlet section, the velocity is lowered and rose on the wall near inlet and outlet along axis, and the velocity distribution on the corners are seriously uneven.