Numerical Simulation And Experimental Study Of Hydrodynamic Cavitation Reactor With Triangular Multi-hole Orifice Plates

Cavitation phenomenon is a complicated phase transition processduring which liquid is changed into gas. The movement and collapse ofcavitation bubbles in the liquid can cause extreme physical conditions suchas high temperature and pressure, shock wave, high speed shooting flow,etc, which would do great harm to equipments. As a result, it is necessaryto avoid cavitation as much as possible for hydraulic machinery. However,this kind of characteristics of cavitation can also help generate largeamounts of energy. It is a brand-new discipline to make use of the energyreleased when cavitation bubbles collapse. For example, it can providespecial environments for some physical and chemical reactions which maynot happen in usual conditions.In order to probe into the mechanism and effect of hydrodynamiccavitation and the basic low of how to enhance it, this thesis is organizedon the basis of a comprehensive analysis of scientific literatures at homeand abroad and all the experiments carried out in the Hydraulics Laboratory at ZheJiang University of Technology. Advanced measuring devices, suchas three-dimensional Particle Image Velocimetry, High-Speed Photography,and Electric Multi-pressure Scanivalve are all adopted.First, an effective equipment of hydrodynamic cavitation was set up.Second, based on computer fluid dynamic theory, the CFD softwareFlow-3D was used to simulate the flow fields of cavitation in order toverify the effect of hydrodynamic cavitation theoretically. Then, we found anew method to capture the free radicals, which was used to measure theamount of hydroxyl free radical. Based on this, the comparing of differentlayout orifice plates on the effect of cavitation was studied to realize theoptimum hydrodynamic cavitation condititions.Through numerical simulation, statistics the orifice plate downstreampressure, cavitation number and flow field can be drawn. It was found thatsuch elements would influence civitation enhancement, the orifice plate oflayout, opening rate and the velocity of flow before orifice. Through theexperiment, it was possible to figure out the relation between flow andimport pressure, flow and cavitation number; the longitudinal velocity andvertical velocity with the change of the flow in the orifice platedownstream. At the same time, the hydroxyl free radical was generatedbetween experiments.