Study On Hydrodynamic Noise Source Characteristics Of Underwater High-speed Vehicle

For high-speed underwater vehicles,the size of hydrodynamic noise is an important factor affecting its concealment.Therefore,it is of practical significance to study the hydrodynamic noise of underwater high-speed vehicles.In this thesis,the underwater vehicle is taken as the research object,and the hydrodynamic noise calculation method of underwater high-speed vehicle is studied.In this thesis,the numerical simulation method of flow noise of underwater high-speed vehicle is studied firstly.In order to determine a relatively accurate calculation method of flow noise,this thesis explores three different numerical simulation calculation methods of flow noise based on the Fluent module in Ansys.The comparison with the model test results shows that the initial flow field is calculated by transient calculation combined with RNG k-ε model,and the transient calculation method of large eddy simulation model combined with FW-H acoustic model is used as the initial value,which can better predict the flow noise of underwater high-speed vehicle.Aiming at the flow-induced noise of underwater high-speed vehicle,the simplified equivalent model of the rotating body is first simplified according to the linear characteristics and structural characteristics of the underwater high-speed vehicle.Then,the wavenumberfrequency spectrum of the turbulent fluctuating pressure of the flow excitation force is used as the input.Based on the modal analysis method and the simplified equivalent model of the underwater vehicle,the calculation method of the flow-induced noise of the underwater highspeed vehicle is established.Compared with the flow-induced noise calculation method based on the structural discretization method and the test results,the accuracy of the flow-induced noise calculation method of the underwater high-speed vehicle based on the modal analysis method proposed in this thesis is verified,and it is found that compared with the structural discretization method.The flow-induced noise calculation method based on the modal analysis method can better reflect the specific influence of the structural mode of the underwater high-speed vehicle on its flow-induced noise.Then,the flow-induced noise calculation method based on modal analysis method is used to calculate the flow-induced noise of underwater vehicles with different shell thicknesses.The results show that under the shell thickness studied in this thesis,the flow-induced noise decreases with the increase of shell thickness.The increase of shell thickness reduces the vibration of the shell surface,which further illustrates the superiority of the flow-induced noise calculation method based on modal analysis method in this thesis.Finally,based on the calculation method of flow noise and flow-induced noise of underwater high-speed vehicle proposed in this thesis,the contribution of flow noise and flow-induced noise in the hydrodynamic noise of underwater high-speed vehicle under the same working conditions is explored.Through comparative analysis,it is found that under the near-field conditions,the flow noise of the underwater high-speed vehicle studied in this thesis is greater than the flow-induced noise at each frequency point,and its flow noise occupies the dominant position of hydrodynamic noise.The research work in this thesis can provide reference for hydrodynamic noise prediction and acoustic stealth design of underwater high-speed vehicles.