Reaseach On Design And Flow Field Characteristic Of The Pumpjet Propulsor

Compared with conventional propeller,the pumpjet propulsor has the advantages of low noise,high efficiency,great reliability and good maneuverability.However,due to the complexity and the strong military application background of the pumpjet propulsor,the present literature review suggests the relevant research for a pumpjet propulsor is few and far between,and it is difficult to obtain a detailed research data of the pumpjet propulsor.The domestic research about the pumpjet propulsor is still in the initial stage.Especially the research of the design of pumpjet propulsor,hydrodynamic performance,cavitation characteristics and tip clearance flow is few and few.The in-depth and systemic research on the tip clearance flow has not been carried out yet.The systemic and detailed research for the pumpjet propulsor is good for the improvement of the performance of the Underwater Water Vehicle(UUV)and has a great influence on the progress of related research fields.In addition,there is a remarkable significance to enhance the combat concealment and high efficiency of our water weapons,such as water submarine and torpedo.Thus,this paper is mainly focused on the design technique and field flow characteristic of the pumpjet propulsor.The systemic research and analyze of the design theory,general scheme design,numerical calculation of 3D field flow,the prediction of cavitation performance and the tip clearance flow for the pumpjet propulsor is carried out.The mainly research contents and achievements is concluded as follows:(1)Research on structure design and modeling method of pumpjet populsor1)The general structure of pump jet propuslor system is given.The research theory of the propulsor,including the theory of the rotor,the stator,the duct and other components,is studied.2)Based on the lifting method,the resolving method of optimal circulation of the rotor is established according to the lifting line method and variation method.The stator blade has been designed based on correction factor method.The accelerating duct has been applied.The scheme determination and structure design of the pumpjet propulsor is carried out.3)Three dimensional modeling method of propeller blade is established by using the conversion between the foil shape point and the point of view point.Meanwhile,the Siemens UG NX software is applied for the modeling and virtual assembly of the pumpjet propulsor.(2)Calculation and analyze of 3D flow field of the pumpjet propulsor1)The numerical calculation model of 3D flow field of the pumpjet propulsor is established.The Reynolds averaged Navier-Stokes(RANS)equations is used to solve the 3D flow field,and the SST k-? turbulence model is applied for the close of numerical simulation.The finite volume method is used to discrete the governing equations and the turbulence model.The SIMPLEC algorithm is applied for the coupling of pressure and velocity.2)According to the relative complex structure of the pumpjet propulsor,the re processing software ANSYS ICEM is used,and based on the block idea,the method of structured grid of calculation domain that adapts the connection of internal interface is applied.3)The numerical simulations and analyze of hydrodynamic performance of E779 A propeller is carried out with different working conditions,and the numerical calculation method and model is verified.4)The numerical simulations and analyze of 3D flow field of pumpjet propulsor with different advance ratios,the hydrodynamic performance of pumpjet propulsor is achieved.When the advance ratio J is 1.23,the maximum of efficiency is 67.99%.The balance performance of pumpjet propulsor is ideal.Besides,the feature and regularity of the distribution of pressure and velocity of the internal flow field is carried out.(3)Prediction and research on the cavitation performance of the pumpjet propulsor1)According to the characteristic of the cavitating flow field of the pumpjet propulsor,the turbulence model is modified,the cavitation model is selected very reasonably.The calculation model and method of cavitating flow field of the pumpjet propulsor is established.The NACA66 and E779 A propeller is selected to verify the numerical simulation method.2)The numerical simulations of cavitating flow of pumpjet propulsor with different working conditions,the hydrodynamic performance of pumpjet propulsor is achieved.After the occurrence of cavitation,the efficiency reaches the maximum 59% at J=1.23.Compared with the condition of non-cavitation,the efficiency drops sharply,up to 19.38%(J=0.98).3)The analyze of the variation of cavitating pressure filed of the pumpjet propulsor is studied.The stator blade can delay and reduce the effect of cavitation.The influence regularity of the rotation speed of rotor blade,inflow velocity and cavitation number for the cavitation characteristic is carried out.(4)Research on the tip clearance flow field of the pumpjet propulsor1)The 3D model and structured gird of the pumpjet propulsor with different tip clearance size is generated.The post processing of the tip clearance flow field of the pumpjet propulsor is emphasized.2)According to the post processing of the tip clearance flow field,the characteristic of the tip clearance flow field is described.The working mechanism and structure of the tip clearance flow field is given.The formation principle and main components of tip clearance vortex is studied.The transportation and development of the tip clearance flow field is descried and analyzed.The research on tip clearance impact on the velocity and pressure field inside the pumpjet propulsor duct is adapted.3)According to the comparison of hydrodynamic performance of pumpjet propulsor with different tip clearance size,the effect regularity of tip clearance size on the hydrodynamic performance of pumpjet propulsor is achieved.The distribution regularity of the velocity and pressure with different tip clearance size is given.4)According to the extraction data of cavitation contours and axial area,the cavitation characteristic of the pumpjet propulsor is given.The effect regularity of tip clearance size on the cavitation characteristic of pumpjet propulsor is studied.The variation of cavitation area of rotor blade with different tip clearance size is studied.Based on the cavitating hydrodynamic calculation,the comprehensive influence of tip clearance size on the cavitation performance is given.