Flow Characteristic And Numerical Simulation Of Narrow Slit Contraction

With the rapid development of construction of high dam of our country, it is also more and more outstanding that the energy dissipation problem of hydropower station. Practice verifies, slitting energy dissipation training can break through convention traditional mode such as nose ridge energy dissipation, utilizing the contractility of selects the ridge and spandrel wall make the rivers longitudinal and spreading, aggravate the rivers to move disorderlily, fully mix gas, having improved the rate of energy dissipation, reduced to the river bed washout At present, slitting energy dissipation have been used in high flood peak hydropower station widely, becoming one high-efficiently energy dissipation training.Because of the rapid shrink of the side wall, enable Current of water of slitting contraction section production steep shock-wave, the existence of the shock-wave makes the characteristic of the current of water of contraction section complicated, mostly test various water conservancy parameters by model test at present, the computing technologies of water conservancy mostly sew and choose the straight line slits selects the ridge, the achievement made is limited, but has offered the method to study to us.This text catches and sews and chooses the main characteristic that something shaped like a tongue fully spreads on the longitudinal space of flowing water narrowly, consider the longitudinal velocity of flow of the rivers is far greater than the horizontal velocity of flow while shrinking section, pressure is far greater than the longitudinal change along the horizontal change, thus neglected the influence on shrinking one section of rivers characteristics of the horizontal change, press the change law along the longitudinal level of rivers characteristic of two-dimentional case study. Employ N-S equation, continuous equation, consider flood peak lost energy equation, set up, calculate symmetrical straight line flat type narrow to sew, choose bank shrink section water conservancy mathematical model of key element, adopt method that dispersed difference divide carry on numerical simulation calculate, result of calculation indicate model and exactness of computing technology accuracy compared with experimental result, can be used for calculating the baseplate pressure and analysis contraction section fluent change characteristic.Obtaining from equation of continuity of slits selects the ridge contraction section current of water and energy equation, analyse and research Fluent angle of departure of slits selects the ridge, obtained the computation to slit selects the ridge current of water angle of departure the formula, result of calculation indicate exactness of formula, can used for, confirm the Angle of departure of Slits selects the ridge.To slits the jet flow collide to disappear the efficiency research, has not studied yet at present. In order to choose distance most large particle to produce firing angle as boundary point, will slit exports the cross section current of water to divide into two parts, and regards as these two parts of current of water two particles, neglect air drag, stave, mixes the gas and so on the influences, particle path regarding as has certain initial velocity and the angle of departure free projectile motion, the particle collides in this course. This text has derived and can subdue the rate formula to disappears the efficiency of collision, and has calculated an example.