The Improve Of Mathematic Model For Spray Caused By Jet From Flip Bucket And Study On Affecting Factor

This paper studies the spray from the jet due to the use of flip buckets in the hydraulicand hydroelectric engineering. Based on the study of spray mechanism, amathematical model for it is established, and furthermore, factors affecting the resultsof the model are evaluated, too. The followings are studied in the paper: (1) A study of the characteristic of the jet including initial parameters, trajectories,and impinging is conducted. Using energy equation, an equation for initial parametersis founded. Considering gravity, resistance, buoyancy, and wind power, anexpression is used for developing tracks of trajectories. Hydraulic parameters afterimpinging of two jets are also given according to momentum equation. (2) The shape and spray flux of the jet are studied in the region where the jetplunges into the tailwater. Distribution functions of stochastic variables includinginitial spray velocities, spray angles, deviation angles and diameters of droplets areestablished in the paper. Considering gravity, resistance, buoyancy, and wind power,the spray behaviors of droplets are studied, and a differential equation of randommotion is put forward. (3) Based on analyzing movement of mist flow in the diffusion zone, three mode ofmotions — transport, relative motion and turbulent motion, are deep studied.According to the law of mass conservation, a differential equation describing 3Ddiffuse of mist flow is brought up. Supposing 2D constant mist flow, a method tocompute the intensity of rainfall in the diffusion zone is founded. (4) In the computation for the range of spray and intensity of rainfall, consideringwind power and terrain respectively, the results from the mathematic model indicate agood adaptation. (5) Using the mathematic model, the feedback and verifying analysis of spray forManwan, Lijiaxia, Wujiangdu and Ertan hydropower station is carried out, and theresults meet the prototype data well. (6) Using the mathematic model, the prediction of spray for Hongkou and Baihetanhydropower station is carried out, and advice for reducing hazard of spray isproposed.