The Mechanism Of The Flow Control And Noise Reduction Based On The Bionic Technology

The hydrodynamic noise of the underwater vehicle will become the main noise source at high speed,which seriously damages the acoustic stealth performance and combat performance of the underwater vehicle.The mainly method of controlling the hydrodynamic noise of underwater vehicle is linear optimization.The research on reducing the hydrodynamic noise of underwater vehicle through flow control is less.This paper proposes a bionic-based underwater vehicle hydrodynamic noise control method,which simulates birds with silent movement ability such as humpback whales,owls,etc.A serrations structure is applied to the leading edge and trailing of the SUBOFF sail hull to control the flow and reduce the hydrodynamic noise of the underwater vehicle.The noise reduction mechanism and noise reduction effect of the bionic structure are studied.In order to make up for the lack of complicated three-dimensional flow phenomenon in the joint between the sail hull and submarine body of the traditional research.In this paper,the model of the SUBOFF sail hull with part of the submarine body is taken as the research object.The large eddy simulation of the flow field is carried out,the turbulent pulsating pressure is extracted,and the flow-induced noise calculation is completed by the sound analogy and combination of finite element and infinite element.The unstable flow phenomenon such as the horseshoe vortex,the boundary layer separation and the tail vortex shedding caused by the flow through the sail hull is analyzed and their contribution to flow noise is analyzed.On this basis,the mechanism of flow and noise control of leading-edge serrations structure and trailing-edge serrations structure is analyzed.It is found that the leading-edge serrations structure and the trailing-edge serrations structure delay the separation of the boundary layer of the surface of the sail hull.The leading-edge serrations structure weakens the horseshoe vortex,and the trailing-edge serrations structure accelerates the breaking of the vortex structure at the trailing edge of the sail hull,thus reducing the flow-induced noise of the sail hull.The flow-induced noise of serrations structure with different amplitude and different wavelength is calculated.The relationship between their changes and the amount of noise reduction is studied and the serrations structure with the best noise reduction effect is determined.Finally,the original model and the model with leading-edge serrations structure are designed.The hydrodynamic noise measurement test is carried out by applying the reverberation method and turbulent pulsation pressure measurement method in gravity water tunnel.The noise reduction effect of the leading-edge serrations structure is further evaluated,and the accuracy of numerical simulation and analysis is verified.The research results of this paper provide a new idea for the flow control and hydrodynamic noise control of underwater vehicles,and provide a reference for the bionic flow and noise control of underwater vehicles.