Influence Factors Simulation Study Of The Self-Exicited Oscillation Pulsed Jet Device And Nozzle Structure Optimized Design

In this dissertation,the self-excited oscillation pulsed jet nozzles,used in the cleaning of industrial oil tank bottom sludge,have been studied. In the conditions of low pressure and large flux,a new pulsed jet method of cleaning bottom sludge is firstly proposed. The mechanism of self-excited pulse action is demonstrated and the numerical optimize design theory of the self-excited nozzle therefore is promoted. The unsteady cavitations model is set up and the self-excited oscillation chamber's flow field is simulated. The model experiments of self-excited oscillation nozzle have been conducted to verify the theories.At last,nozzle structure optimized design theory is build,it's useful for dirrecting actually industrial design.In Chapter 1: The technologies of the treatment of bottom oil sludge.and water jet cleaning are introduced, the latest development on them are summarized.In Chapter 2: The frenquency characteristic of self-excited oscillation nozzle is deduced based on small disturb hydro-network theory,all kinds of parameters' influence to frenquency are analysized, wave speed's influence is emphasized especially.In Chapter 3: The numerical theory of steady cavitations has been set up by the studying of the two-fluid model of liquid and vapor. The control equations are put forward and the method of equations segregating, the mesh grid transformation and SIMPLE for two-phase fluid is promoted. The method of sharing pressure by mass fraction is discussed especially.In chapter 4: Unsteady cavitations model is presented and improved too. The mechanism of the self-excited pulse is expatiated through the dividing of the pressure, velocity and volume fraction zone. The outlines on how to form pulse jet are summarized.In chapter 5: The effects of the nozzle configuration and the operating parameters to the self-excited nozzle have been discussed by numerical simulation analysis,the optimal range of structural parameters and operate parameters are summarized.In the chapter 6: The verification has been made from the experiment,and the last optimal range of structural parameters and operate parameters are confirmed.In chapter 7: The summarization of the dissertation is given and the suggestions ofluriher researches are promoted.