基于降雨分析的窄缝挑坎消能工水翅特性研究

摘要

通过建立窄缝挑坎消能工物理模型，模拟研究出射水流的激溅水翅问题。通过调整窄缝挑坎体型参数(弗氏数Fr、收缩比β、挑角θ)以获得不同出射水流条件，进行对比试验分析水翅的成因及其引起的降雨量区域强度变化趋势，甄别影响水翅形成及其强弱变化的主要水力参数，总结其变化规律。研究表明，窄缝消能工水舌的外缘挑距和入水长度均会随着弗汝德数Fr的增加而增大，挑坎下游典型区域的雨量分布亦随之发生变化；随着窄缝收缩角的增大，急流冲击波波角逐渐变小，水翅向岸边扩散的角度变小，冲击波交汇点距离窄缝出口更近，降雨向岸边扩散的范围也逐渐变小；此外收缩比与水舌外缘挑距和入水长度变化成反比。本研究成果可进一步加深对窄缝挑坎消能工水力特性尤其是水翅形成机理的认知，为工程实践提供优化依据。%A physical model of slit-type energy dissipator was built to study the water wing through adjusting the shape parameters ( Froude number Fr, contraction ratioβ, and pick angleθ) to obtain different jet flow conditions. The changes of precipitation intensity and the causes of water wing were analyzed through comparison, and the hy-draulic factors which affect the water wing formation and its intensity variation were summarized. Results indicate that the peripheral jet trajectory length and dived length of water tongue increased with the increasing of Fr,and the rainfall distribution in typical areas downstream the bucket changed in correspondence. Moreover, with the increase of contraction angle, shock wave angle became small;the diffusion angle of the water wing to shore was also smal-ler;the intersection of shock waves became closer to the outlet of narrow slit;and correspondingly the range of rain-fall diffusion also decreased. In addition, the contraction ratio was inversely proportional to the peripheral jet trajec-tory length and dived length of water tongue. The research couldenrich the understanding of hydraulic characteris-tics, in particular, the water wing formation mechanism of the slit-type energy dissipation and provide basis for the optimization of projects.