Research On The Influence Of Water Nuclei On Water-exit Cavitation And Hydrodynamic Load Of Underwater Vehicle

The cavitation flow of underwater vehicle is related to gas-vapor-liquid multiphase flow,including a variety of cavitation dynamic behaviors such as bubble initiation,development,shedding and collapse.It plays an important role in structural stability,ballistic stability,vibration reduction and noise reduction of underwater vehicle.There are rich nuclei in real rivers and lakes.However,at present,most of the cavitation flow tests of underwater vehicles ignore the influence of nuclei,which is easy to cause scale effect and reduce the engineering application value of the results of model tests.Therefore,it is urgent to study the effect of nuclei on the underwater vehicle attached cavitation.Based on the vertical constrained underwater launch platform of Harbin Engineering University,this paper studies the effect of nuclei on the effluent of underwater vehicle attached cavitation.The cavitation shape,cavitation pressure fluctuation and resistance characteristics under different nuclei concentrations are studied in detail.The main contents of this paper are as follows:A vertically constrained underwater launch platform is built based on decompression system,motion control system,data acquisition system,nuclei seeding system and nuclei testing system.The visualization of cavitation flow and the synchronization of load data acquisition are realized.Cavitation flow visualization and load data acquisition are carried out simultaneously.the test condition is designed based on the test platform.And the accuracy of the test data is verified by sensor calibration and test repeatability verification.The study on the effect of nuclei concentration on cavitation flow characteristics was carried out,including cavitation development process and water-exit collapse.According to the different growth mode of cavitation,the attached cavitation of streamline head body,cone head body and head body is divided into natural separation type cavitation and forced separation type cavitation.The effect of nuclei concentration on cavitation development and water-exit collapse has been obtained.Based on the pressure load measurement system,the study on the effect of nuclei concentration on the pressure fluctuation of the underwater vehicle has been carried out.According to the law of pressure change,the pressure section of the navigation body is divided into cavitation primary zone and cavitation development zone.Under different nuclei concentrations,the effects of natural separation cavitation and forced separation cavitation on the cavitation primary zone and cavitation development zone of the underwater vehicle are obtained.Based on the axial force measurement system,the study on the resistance characteristics of the underwater vehicle attached cavitation is carried out.The effect of cavitation coverage ratio and type of cavitation on the resistance characteristics of underwater vehicle under different nuclei concentration is obtained.