Study On The Effect Of Clearance On Flow Mechanism Of Liquid Oxygen Tubine Pump

In recent years,the rapid development of aerospace technology promotes the rapid improvement of liquid rocket engine technology.As the core component of liquid rocket engine,the safety and reliability of liquid oxygen turbo pump are particularly important.In the actual working conditions of liquid oxygen turbine pump,the rotor moves in the axial direction between the front and rear cover plates,and also has radial vibration in high-speed operation.The clearance between the front and rear cover plates of liquid oxygen turbine pump plays an important role in its operation.In this paper,the liquid oxygen turbine pump is taken as the research object to explore the change of flow field in the liquid oxygen turbine pump under the condition of different coaxial and radial clearance changes,and to reveal its influencing factors and action mechanism.This paper makes an in-depth exploration of the following aspects:1.Provided by using the commercial software CFX,the SST turbulence model is selected for foundation clearance structure grew up under the covers seven different point of each traffic conditions to carry on the numerical simulation,and the calculation of the turbine pump lift and efficiency change with flow situation analysis,to explore the changing flow mechanism of the change of the liquid oxygen turbine pump external characteristic.2.For axial gap and radial clearance structure of liquid oxygen pump turbine model under different flow conditions constant simulation calculation,the flow characteristics of and from two aspects:energy and stability characteristics,study the flow field in the external characteristic,axial force and the changing rule of the change with clearance,clearance structure change on the inner mechanism of the liquid oxygen turbine pump flow influence.3.Of lox turbopump coaxial structure to the clearance of the same calculation of unsteady flow conditions in the basin,and the diffusion cascade turbopump rotor river flow and circumferential monitoring stations,and USES the fast Fourier transform?FFT?,the analysis of measuring point of pressure pulsation in the basin and its change rule along the flow direction and circumferential and axial clearance under unsteady flow change on the influence of the pressure pulsation.The research results show that"hump"phenomenon is found in the external characteristic curves of each gap structure,and the"hump"region appears in the region where Q/Q_BEP is 0.74 to 0.87.In the different coaxial clearance structure,the hydraulic loss in the induced and centrifugal wheel basin and the front and rear cover plate basin is the main factor affecting the change of the external characteristics of the liquid oxygen turbine pump.In each radial clearance structure,the contribution of front cover clearance watershed to hydraulic loss increases obviously with the increase of radial clearance.In the study of axial force,axial gap and radial gap structure,clearance down wall stress is liquid oxygen turbine pump is always the size of the axial force and the direction of the dominant factor,and rotor axial movement influenced the X1 and X2clearance,the size of the change in the cavity between the fluid flow and distribution,and change the pressure distribution in the cavity,led to the change of the axial force together.The radial movement of the rotor changes the flow and vortex distribution in the cavity,and thus influences the axial force.In the analysis of unsteady pressure pulsation,it is found that the pressure pulsation is mainly generated by the unstable flow at the interface between the induction wheel and the centrifugal wheel,and the axial balance movement of the rotor mainly changes the flow at the interface between the induction wheel and the centrifugal wheel,thus influencing the pulsation characteristics of the whole basin.