圆弧鼻坎射流水舌起挑角的试验研究

Experimental Investigation of the Takeoff Angle of Free Jet from the Circular-shaped Flip Bucket

基于圆弧鼻坎挑射流物理模型试验,考虑脉动流速对水舌上缘挑角的影响,研究上缘起挑角的理论公式;通过引入两个系数同时考虑脉动流速和断面水深对下缘起挑角的影响,选用49组试验数据,采用误差分析方法,提出下缘挑角的半经验半理论公式。与前人的公式相比,上缘挑角的理论公式形式简单,下缘挑角公式考虑因素较多。两公式误差均小于13%,用于计算进口水平和倾斜渠道后接圆弧鼻坎挑射流水舌上、下缘起挑角是有效的,进而确定射流冲击点位置和冲击区范围也是有效的。

Free jet is considered a major element in the design of flood discharging and energy dissipation installations of high dams. The hydraulic characteristics of the jet that jumps through a flip bucket is an important research subject in the dissipation design. Based on the physical model test, the theoretical equation of the upper takeoff angle was discussed considering the influence of the fluctuating velocity, and then the lower takeoff angle was analyzed through two introduced parameters considering the fluctuating velocity and flow depth of the cross section. In the study of the lower takeoff angle, 49 units of test data were analyzed with error analysis method, and then a semi-empirical and semi-theoretical equation of the lower takeoff angle was put forward. The formula of upper takeoff angle has a simple form and that of the lower angle includes more affecting factors comparing to previous expressions. The formulas have the errors smaller than 13%, so they are applicable in the calculation of the takeoff angles of free jet from a flip bucket inserted at the end of the outlet, for both the horizontal and the inclined channels, based on which the location of the plunging point and the scope of plunging zones can be determined.