Structural Design And Flow-induced Vibration Noise Characteristics Of New Pump-jet Thruster

Pump-jet thruster radiates fluid noise and structural noise when it works.Therefore,the study and control of flow-induced vibration noise help a lot to improve the acoustic concealment performance of naval vessels.In this paper,proto pump-jet thruster and new pump-jet thruster are taken as research objects.Flow field,vibration field and noise field are studied comprehensively.The main contents are summarized as follows:The design methods of components of prototype and new pump-jet thruster are introduced.Stator Blades are designed by Streamline method,rotor blades are designed by lift method and duct section design method are described.Exploratory mind is proposed to design the rotor blade crown sectionally.Flow field performance is calculated to verify the rationality of design method.In addition,three-dimensional modeling of prototype and new pump-jet thruster with crown are completed.Based on numerical method,unsteady hydrodynamic calculations of prototype and new pump-jet thruster are carried out.On one hand,hydrodynamic characteristics of the new type pump-jet thruster are discussed from the aspects of open water characteristics,blade excitation force characteristics and velocity and pressure distribution at observation points;On the other hand,flow field characteristics of the prototype and the new pump-jet thruster are compared from the aspects of open water characteristic parameters,blade excitation force,internal flow field fluctuating pressure and gap flow fluctuating pressure in order to analyze the Uniform effect of the new type of pump-jet thruster with rotor blades’ crown.A finite element model of prototype and new pump-jet is developed to carry out the dry and wet modes.And the law of modal frequency are summarized.Combining with the results of flow field calculation,the one-way fluid-solid coupling calculation is carried out for the new type of pump-jet thruster.The deformation characteristics and stress distribution of rotor blades,stator blades and duct in all directions are analyzed.Besides,the spectrum characteristics of blades deformation are compared.Based on Virtual Lab software,the fluid radiated noise and structure radiated noise of prototype and new pump-jet thruster are calculated.According to the fluid field results,the sound field characteristics of stationary and rotating parts as well as the whole parts are analyzed respectively.Finally,the sound propagation phenomenon and directivity of new pump-jet thruster are studied and differences between prototype and new pump-jet thruster are compared.The structural radiated noise calculation is based on the fluid-structure coupling calculation results in Chapter IV.The sound power of the structure surface and the sound pressure distribution of new pump-jet thruster are analyzed.After analyzing acoustic-vibration coupling response,the structural radiated noise of characteristic points of prototype and new pump-jet thruster are compared.