挑流水舌空中运动扩散特性研究

水利工程100米级以上高坝中挑流消能占比80%以上，但容易引起下游冲刷和雾化，在挑流消能设计中，为了防止冲刷和雾化，需准确估算水舌挑距等技术参数。然而，由于对挑坎出口断面的流速分布及不同速度量级水舌空中运动扩散特性认识不清，导致现有挑距等技术参数的计算理论公式虽多，但计算结果差异极大，严重制约了挑流消能设计水平。本项目拟采用系列模型试验和原型观测，结合数值模拟和理论分析的方法，通过对连续坎、窄缝坎、扩散坎三种典型挑坎挑流水舌运动扩散特性的对比分析，揭示挑坎出口断面流速分布规律并建立其理论计算公式，查明挑流水舌运动扩散特性参数的缩尺影响及其定量关系，获取挑流水舌运动扩散特性参数与挑坎段体型参数、坎前来流条件之间的关系和变化规律，建立一套挑流水舌形态、纵横向扩散、挑距、入水范围、入水角等运动扩散特性参数的高精度计算方法，为挑流消能工的设计提供理论支撑，为深入研究射流冲刷、雾化等提供科学依据。

In the water conservancy project, ski-jump energy dissipation is applied in the 100-meter-level high dam more than 80%, however, it could easily cause scour and atomization in the downstream. In the design of ski-jump energy dissipation, in order to prevent the scouring and atomization, it is necessary to accurately estimate the technical parameters such as the nappe trajectory length and the range of nappe plunging into the pool. However, due to the unclear understanding of the velocity distribution at the exit section of the flip bucket and motion diffusion characteristics of the nappe with different velocity orders, there are many theoretical formulas for calculating the technical parameters such as the nappe trajectory length and the range of nappe plunging into the pool, yet with greatly varied results, which seriously restricts the design level and application effect.This project is intended to conduct a series of model tests and prototype observations combined with numerical simulation and theoretical analysis to comparatively analyze the hydraulic characteristics of three (continuous, silt-type and diffusion) typical flip buckets. The goals of this study are 1) to learn flow velocity distribution of the exit section of the flip bucket and establish the theoretical calculation formula; 2) to reveal the scale effect and quantitative relationship of the hydraulic characteristics of the flip bucket at the model scale; 3) to find out the relationship between the hydraulic characteristics of the nappe and the conditions of the incoming flow and the shape parameters of the bucket section; and to establish a set of high precision calculation methods for nappe diffusion in the longitudinal and horizontal direction, nappe trajectory length, the range and angle of nappe plunging into the pool and distributions of velocity in different sections under different conditions of ski-jump types and outlet's shape parameters. This study would be able to provide theoretical support for ski-jump energy dissipation structure design, and to provide scientific basis for in-depth study of jet scouring and atomization.