Study On The Regression Analysis Of Hydrodynamic Characteristics Around The Underwater Vehicle

Compared with conventional launched missile,submarine launched missile has obvious advantages in maneuverability,concealment and attack ability,then a lot of research work from different aspects begin to be carried out.Similarly,the process of an underwater vehicle with ventilated cavity involves launching from the emitter,underwater motion and water-exit.Clound cavitation usually appears surrounding the vehicle surface before exiting water,with the characteristics of the break-off,shedding and quasi-periodic variation.Subsequently,these oscillation characteristics affect maneuvering stability.And pressure plulses caused by cavitation collapse when vehicles going through the free surface will form the key governing the strength of structures.Thus analysis on pressure fluctuation charactiristics of the vehicle surface is important to applications in engineering.The pressure charactiristics of the process of underwater motion and water-exit are achieved with the simulation method.Based on this,a mathematical model of the pressure is developed by using the linear regression mathematical statistics.The main contents and conclusions are as follows:The application of the numerical calculation of the underwater motion and water exit hydrodynamics of an underwater vehicle and the mathematical statistics method are evaluated in the project.Based on layering dynamic mesh method,the numerical simulation with Level Set method and FBM turbulent model is adopted to study the unsteady flow structure of ventilated cavitation to obtain the pressure data for the linear regression mathematical statistics.The simulation results are validated by experimental results.Based on the pressure data achieved with the numerical simulation,the feasibility and reliability of the regression method of the pressure characteristic of the vehicle are verified with statistical analysis and neural network method.Firstly,descriptive analysis is applied to discuss the characteristics of pressure distribution surrounding the vehicle surface.The distributions of mean and variance of the pressure show that the pressure decreases with the discreasing of the depth of water.Median distribution of the pressure and envelope line explain the growth and the trend of ventilated cavitation,respectively.Secondly,correlation analysis of pressure coefficient shows that the depth of water,sailing time and monitoring point are the biggest influence factor.Finally,the application of neural network method verificates the feasibility of the regression analysis of pressure coefficient.Comparisons of the development of the ventilated cavitation of the numerical simulation with the linear regression mathematical results show reliability of the regression method.Based on the analysis of the characteristic of the underwater-launched,segmenting data and the effective selection of the monitoring point are determined to discuss the analysis method of the pressure characteristic of the vehicle.The results show that the pressure surrounding the vehicle surface keeps high and increases in the form of curve with the decreasing of the depth of the water in the stage of the evolution of the ventilated cavitation.And in the stage of the relatively stable,the pressure decreases with the decreasing of the depth of the water.The analysis of the data from three monitoring points shows that the accuracy of the model is more reliable and the depth of the water is the biggest factor.