A-type Twin-screw Pump Design And Multi-field Coupling Analysis

With the rapid development of the economy,energy demand is growing and the focus of energy extraction is shifting from inland to deep sea areas.Due to the diversity and variability of subsea media,twin-screw pumps have been the core equipment for transporting oil and gas resources from sea to land and the focus of research on fluid drive and control units.The performance of twin-screw pumps is affected by the gas content rate and internal flow field forces,which may threaten the safe operation of twin-screw pumps under critical operating conditions and cause unnecessary losses.This paper takes twin-screw pump as the research object,establishes the flow field model,internal leakage model and master and driven screw model of twin-screw pump,studies the deformation law of the master and driven screw under the action of flow-thermal-solid coupling,reveals the influence law of the speed,differential pressure,flow rate,gas content rate and clearance of twin-screw pump on the flow field and volumetric characteristics of the pump,the main research work is as follows:(1)Using the combination of long-amplitude cycloid-involute and short-amplitude cycloid and the theory of spatial transformation,the end profiles of the master and driven screws of the twin-screw pump were derived,and the parametric program of the master and driven screw end profiles was written in Matlab;the mathematical model of the screw profile with circular arc transition was established,and the radius of the driven screw end profile was optimized;the three-dimensional model of the master and driven screws and the flow field model were established,the location of the leakage was predicted,and the mathematical model of the leakage channels of the top clearance,inter-teeth clearance and tooth side clearance was derived.(2)The pressure and velocity characteristics of the internal flow field of the twin-screw pump were analyzed by the computational fluid dynamics(CFD)method,and the pressure and velocity values in the pump were compared and analyzed by changing the clearance between the top and the teeth of the master and driven screws,and the optimal values of each clearance in the pump were obtained.(3)According to the established shear flow and differential pressure flow gap leakage model of the flow field in the pump,the leakage of the twin-screw pump under different gaps was calculated,and the simulation verified the correctness of the leakage model,revealing the influence law of the speed,differential pressure and GVF of the twin-screw pump on the size of the flow rate and the volumetric efficiency characteristics of the twin-screw pump.(4)The pressure and temperature fields calculated numerically from the flow field of the twin-screw pump were used as the external loads of the master and driven screws,and the flow-solid coupling and flow-thermal-solid coupling analyses were performed on the master and driven screws of the twin-screw pump to reveal the relationship between the deformation and equivalent forces of the master and driven screws and the speed,pressure and temperature of the twin-screw pump.