Time-Frequency Feature Analysis Of The Pulsed Liquid Gas Jet Of The Self-Excited Inspiration Nozzle In Deepwater Conditions

In view of the actual demand,which is about the sediment river and reservior sedmientation to be solved.The paper has done a battery of theoretical analysises and experimental researches about the time-frequency characteristic of self-excited pulsed jet.All of these are based on the previous research about the impact performance and erosion performance of self excited pulsed jet and unite the domestic and international research results.Discussing the correlation about time-frequency distribution between cervix cavity pressure pulsation signal and shock pressure pulse signal,the paper has arrived at the time-frequency rule of the pressure pulse signal,especially the inherent characteristic of frequency component.The first chapter has overviewed the research progress and general situation,which includes an overview of the domestic and foreign scholars on the reservior dredging and water jet,cavitating jet,abrasive water jet,pulse jet and so on,and has summarized the application of self-excited pulsed jet.In the second chapter the mechanism of the self excited pulsed jet in the two states,which are aspirated and unaspirated,is analyzed.And in this chapter the characteristics of them are discussed.Then this chapter has also introduced the method,theory and the advantage of the time frequency analysis of the pressure pulsation signal.The third chapter has carried out the experimental research on the jet performence of the nozzle,which used time-frequency analysis technique to extract the time-frequency characteristics of the jet impact signal and pressure signal.And put the band energy percentage as the indicator,this chapter has analisised and comparied each frequency component energy and frequency distribution,which is about that the nozzle do not breathe and breathe in band energy percentage.According to the time-frequency characteristics of the signal distribution,the paper has discussed the correlation about time-frequency distribution between cervix cavity pressure pulsation signal and shock pressure pulse signal.Under the different operation parameters and structure parameters,what is reached is that the time-frequency rule of the pressure pulse signal,especially the inherent characteristic of frequency component.The research result of this paper has provided the foundation for the theory that is about further study of breathe in self-excited pulsed jet nozzle virbration occurs.And in actual application,it also has afforded the base to carrying out the pulse jet impact frequency modulation.