CFD Numerical Simulation Of Hydrodynamic Cavitation On Nozzle Flow

Cavitation is a process of vapor bubble's generation,growth and breakdown because of the abrupt change of pressure inside the liquid.At the moment of bubble breakdown,instantaneous high temperature and pressure will be produced in the subminiature area around the bubble,and the violence shock wave and high speed jet flow will also be induced.Using extreme condition arosed by hydrodynamic cavitation could strengthen many technologic processe.It possesses of the advantage of low energy consumption,high efficiency,and less pollution,which has broad economic and social benefits.So,hydrodynamic cavitation is widely applied in many fields.Along with the development of the computer technology and calculation method,the computational fluid dynamics (CFD) has become a strong numerical experiment and design method.This dissertation is aimed at finding out the mechanism of hydrodynamic cavitational enhancement and the evolution of bubble dynamics.Then the relationship between enhancement effeet and influcing factors can be built to guide the optimization of hydrodynamic cavitation.It provides the theoretical basis and practical application guidance for hydrodynamic cavitation engineering.Researches are mainly developed into such directions as follow.The many kinds of prevalent general CFD are detailedly introduced in this paper, especially FLUENT fluid calculation software are expounded.Using the software, choosing the standard k ?εturbulence model,the Mixture multiphase flow model and cavitation model with FLUENT to simulate the flow fields of cavitation in nozzle and venturi which obtained pressure field,velocity field,turbulent kinetic energy and volume fraction of vapor characteristics.Analysis of the inlet pressure,the diameter ratio,length ratio effecting on the strength of nozzle cavitation and the cavity flow generation,development and disappearance process of venturi and the inlet pressure,outlet pressure,throat diameter,diffusion length effecting on the strength of venturi cavitation.The results of this dissertation provide a basis for optimal design of nozzle and venturi.