| Counter rotating propeller(CRP)is always a very important propulsion mode for high-speed underwater vehicles.This paper studies the hydrodynamic performance,cavitation and noise performance of CRP.With the demand of high-speed underwater vehicle,the underwater CRP is becoming more and more important It is inevitable that the propeller will produce cavitation,which will reduce the performance of CRP and lead to the surge of pulse force.The existence of cavitation will produce cavitation noise,which will affect the stealth performance of the ship.In recent years,CFD technology is more and more widely used in the field of ship propulsion.In this paper,the hydrodynamic performance,cavitation performance and noise performance of CRP are deeply studied by using the hydrodynamics software.The hydrodynamic law and flow field analysis of the front and rear propeller in the oblique flow condition are carried out,and the CRP in the uniform flow field and non-uniform flow field are analyzed At the same time,the non cavitating noise and cavitating noise of rotor are discussed.The research content of this paper is mainly divided into the following aspectsFirst of all,the research background and significance of the subject are described,and the research progress of propeller hydrodynamic performance at home and abroad,especially the oblique flow condition,is summarized.The research status of cavitation field at home and abroad is summarized,and the research status of underwater propeller noise at home and abroad is summarized Application.Then,the numerical model used in the numerical calculation is introduced,and E779A standard model propeller is selected as the verification example.The hydrodynamic loads of different simulation methods are compared,and the cavitation phenomenon of the blade under specific conditions is calculated;the cavitation radiation noise of a single blade is calculated,and the calculation results and phenomenon are compared with the literature values to verify the rationality of the numerical method.Thirdly,the hydrodynamic characteristics of CRP in oblique flow are calculated by RANS method and sliding grid technology.The independence of grid number is verified.The hydrodynamic characteristics of single blade are analyzed.The pressure fluctuation on blade surface is analyzed.The results show that the larger the oblique flow angle is,the smaller the axial thrust of the rotor is,the interaction of the blades makes the load curve of a single blade produce a local period;the pressure fluctuation on the surface of the blade is affected by the rotation of the blade and the relative position of the blade.Fourth,the cavitation performance of CRP is calculated by using DES.The hydrodynamic performance of CRP under cavitation and non-cavitation conditions is compared.The cavitation performance of CRP under different cavitation numbers is calculated.The influence of cavitation number on cavitation area and volume is analyzed.The influence of advance coefficient on cavitation is also studied.Finally,the influence of the non-uniform flow field on the cavitation performance of the CRP is studied and compared with the uniform flow condition.The results show that the larger the cavitation number and advance coefficient is,the smaller the cavitation area is.Finally,the noise performance of CRP under the conditions of no cavitation and cavitation is calculated,the axial and radial noise attenuation characteristics of CRP are analyzed,and the noise directivity of CRP is analyzed.The influence of inflow velocity and rotating speed on loading noise and thickness noise is considered.The radiated noise of CRP under cavitation condition is studied.The results show that the noise of CRP in axial position is larger than that in radial position;the directivity of loading noise is in shape of "∞"，and the directivity of thickness noise is in shape of "8";the sound pressure level of cavitation noise is much higher than that of non-cavitation noise. |
