Design And Multi-Field Coupling Analysis Of Embedded Tri-Screw Pump

As a precision rotor type displacement pump,the tri-screw pump has the advantages of high flow rate,high working pressure,low-pressure pulsation,and low noise,and is widely used in ships,marine engineering,petrochemicals,food,drainage,and sewage.The traditional three-stage tri-screw pump hydraulic power unit has a large axial dimension and high vibration noise,which cannot meet the needs of submarines,aircraft carriers,and other hydraulic power units with restricted installation space and high silence requirements.Therefore,a new structure of the embedded tri-screw pump is proposed,which is directly embedded in the heart of the servo motor to form a new tri-screw motor pump,which can significantly reduce the volume of the installation space and has the outstanding effect of vibration isolation and noise reduction.Numerical analysis of the structure,internal flow field,and performance of the main components of the embedded tri-screw pump,combined with fluid calculations,fluid-structure coupling,thermo-fluid-structure coupling,and other analytical methods to obtain the distribution of fluid pressure,temperature,flow velocity,and the working conditions of the driving and driven screws in the embedded tri-screw pump.The main research work is as follows.(1)Based on the design theory of the driving and driven screw end profiles of conventional tri-screw pumps,the driving and driven screw end profiles of the embedded tri-screw pump were derived and the rounded tip angle chamfering was carried out.A parametric design procedure for the driving and driven screw end profiles was written using Matlab software.A prototype model of the embedded tri-screw pump was constructed with the target parameters of 20 MPa working pressure and 101 ml/r displacements,and the three-dimensional numerical models of the driving and driven screws were determined.(2)The flow field model of the internal flow channel of an embedded tri-screw pump is constructed,and the variation of pressure,temperature and flow velocity in the internal flow field of the embedded tri-screw pump is studied based on CFD analysis.By varying the center distance of the driving and driven screws to obtain different screw inter-teeth clearance and top clearance,the relationship between the different clearances and the flow field pressure inside the pump is simulated and analyzed,and the distribution patterns between different screw angles and the corresponding flow field velocities.(3)Based on the internal flow field of the embedded tri-screw pump and the structural analysis of the driving and driven screws,the pressure,temperature and screw deformation,and equivalent forces in the flow field of the pump under different operating conditions were obtained using the multi-field coupling analysis method.The deformation and equivalent forces of the driving and driven screws are not directly superimposed on those of the separate loads.(4)Modal analysis of the embedded tri-screw pump and its driving and driven screws was carried out to investigate the vibration patterns of the driving and driven screws in dry,wet,and pre-stressed modes,as well as comparing the first six orders of inherent frequencies in each state.The results of the thermo-hydrodynamic-solid coupling were converted into a rain-flow load matrix,and damage superposition was carried out to calculate the fatigue life,predicting that the damage areas of the d and driven screws were concentrated at the root of the helical groove.