Research On Numerical Method Of Flow-Induced Noise Of Ship Structure

Underwater radiated noise,as an important index in the comprehensive performance of ship structures,has high research value.Underwater radiated noise includes three types of mechanical vibration noise,propeller noise,and hydrodynamic noise generated by the structure under the action of the flow field.Among them,hydrodynamic noise accounts for a large proportion at high speeds.The main components,if not effectively controlled,will seriously restrict the comprehensive performance of ships and underwater vehicles.The flow-induced noise is caused by the interaction of the flow field and the structure.Its formation mechanism and distribution law are not only related to the navigation conditions,hull profile,and appendage structure,but also affected by the internal structure and material properties of the ship.The formation mechanism of flow-induced noise is complex and the influencing factors are many.It is of great research value to carry out effective numerical calculation and discussion of its laws.In this paper,the flow-induced noise of ship structure is taken as the research object,and the numerical calculation method research and engineering application are combined to carry out a numerical calculation method of ship structure flow-induced noise and hydrodynamic noise experimental research.Firstly,this paper summarizes the domestic and foreign research progress of numerical simulation of flow field and numerical calculation of pulsating pressure on the structure surface in detail.The large eddy simulation method is selected as the first method to obtain pulsating pressure load of flow-induced noise in this paper.Then analyze the theoretical basis and commonly used numerical calculation methods of flow-induced noise calculation,consider the characteristics of each method and their respective scope of application,select the acoustic FEM-AML method to calculate the low-frequency current-induced line spectral noise,and select the SEA method to calculate the high-frequency current-induced noise Frequency band noise,thus pointing out the direction for the research methods and technical support of this article.In order to obtain effective pulsating pressure load of flow-induced noise,this paper uses a large eddy simulation method to numerically simulate the turbulent field of a cone-cylinder shell model,and analyzes some key parameters involved in the large eddy simulation method,including the selection of a sub-lattice stress model.The influence of parameters such as the height of the near-wall grid on the validity of the calculation results.The optimal parameters were selected to perform steady-state and transient calculations on the cone-cylinder shell model,and a model verification test based on a gravity water tunnel was performed to verify the large eddy Effectiveness of simulation calculations.Provides a reliable load input for the following flow-induced noise calculations.The pulsating pressure on the surface of the structure obtained by the large eddy simulation method was used as the load input.The acoustic mid-and low-frequency flow-induced line noise of the cone-cylinder shell was calculated using the acoustic FEM-AML technique.For the calculation process of frequency band shock band noise,the differences of two different input methods are compared respectively for the input problem of turbulent boundary layer load in the statistical energy methodA hydrodynamic noise test based on gravity water tunnels was carried out,and the validity of the above numerical methods was verified through comparison,and the laws of hydrodynamic noise testing of gravity water tunnels were discussed.Based on this,this paper proposes a fitting function method,combining acoustic finite element method and statistical energy method,to obtain a numerical calculation method of full-band current-shock band noise,and based on the actual engineering needs based on VAOne and C#language development a full-band current-shock frequency band noise fitting program is provided,which effectively improves the prediction efficiency of underwater structure-induced radiation noise of ship structures.Summarizing the above work,this paper proposes a full-frequency flow-induced noise calculation process,which can provide some reference and practical significance for practical engineering applicationsFinally,this paper applies the above-mentioned calculation method of the full-frequency flow-induced band noise to the SUBOFF standard model.The spatial and frequency distribution of flow-induced noise at different speeds is analyzed qualitatively and quantitatively,and the effects of different damping forms on the flow-induced band noise are discusse.