Key Structure Design And Flow Field Analysis Of High-pressure Three-screw Pump

The three-screw pump has the unique advantages of strong self-priming capacity,low pulsation,low noise,wide range of conveying media,and small vibration.It is widely used in various fluid transmission and conveying applications.At present,the load capacity of most three-screw pumps is low,but as the application of three-screw pumps expands,higher demands are placed on their load pressure.Under high-pressure load,due to the rotation of the screw,it causes a radial bounce in the gap between the bushes where the screw is positioned,which will lead to the phenomenon of shaftholding in severe cases,which limits the development of the screw pump to high pressure.On the other hand,when the screw rotates,the stress is concentrated on the end of the discharge screw,which causes the thread to crack or deform.Therefore,it is of great significance to study the radial clearance and screw structure of high-pressure screw pumps.This paper designs a high-pressure three-screw pump with a load pressure of 25 MPa according to the working principle of the three-screw pump.The main research work is: According to the cycloidal meshing theory of the three-screw pump,the tooth curve curve equation of the master-slave screw is obtained,and the tooth curve is modified based on the radial straight line method;Calculate and further get the equation of theoretical flow.The relationship between the performance parameters and influencing factors of the high-pressure three-screw pump is introduced;the structural design parameters are selected according to the characteristics of the high-pressure three-screw pump;the virtual prototype is constructed using Inventor parameterization and interference detection is performed;and the oil film theory is analyzed and derived The theoretical optimal radial clearance expression of the high-pressure three-screw pump.The oil retaining ring is designed to fix the radial clearance between the master and slave screws and the bushing.In order to verify the rationality and feasibility of the radial clearance design,the main screw is applied by the cylindrical division method.The load was analyzed by finite element method;in order to reduce the root stress of the high-pressure end of the active screw,the structure was optimized by using the helix cone angle.Using Fluent numerical analysis method,the influence of radial clearance on screw torque is analyzed,and the actual radial clearance range of the high-pressure three-screw pump is obtained.In order to further evaluate the design scheme,a flow channel model was established and numerical simulation was performed to analyze the high-pressure process of the screw pump.Finally,the simulation results show that the volumetric efficiency of the three-screw pump is 89% at 25 MPa.The calculation and analysis results show that the high-pressure screw pump designed in this paper can theoretically improve the radial runout of the screw,reduce the root stress of the active screw and avoid tooth root cracking.