Research On The Key Problems Of Magnetic Fluid Sealing Water

Compared with traditional sealing forms such as mechanical seal and packing seal,magnetic fluid seal has the advantages of low leakage rate and low energy consumption.At present,the technology of magnetic fluid seal for sealing gas has became mature.In contrast,Using magnetic fluid to seal water or other liquids still has problems such as unstable two-phase interface,unclear pressure transmission process of multi-pole tooth seal,and weak pressure resistance.This paper aim at the problems of magnetic fluid sealing water,design the sealing structure of the front baffle to reduce the interface instability caused by the relative speed of the two phases and increase the effective sealing time;design the combined sealing structure of the front back impeller to improve the pressure value of the sealing water;use computational fluid dynamics method to simulate the leakage process of the multi-pole tooth seal structure when sealing water,analyze the pressure transmission characteristics of the sealing water and air,and evaluate the sealing performance of combined sealing structure with water baffle and back impeller.The main work of this thesis is as follows:(1)Derive the pressure resistance formula of monopolar tooth magnetic fluid sealing water,calculate the relative speed of magnetic fluid and water,and give the unstable condition of the two-phase interface.(2)According to the Kuet flow model under the condition of coaxial rotation,a symmetrical single-stage magnetic fluid seal structure with a front baffle type is used to study the effect of different inner diameter baffles on the two-phase interface of sealed water,and a front back impeller seal Combined with magnetic fluid sealing combined sealing scheme to improve the overall pressure resistance of the sealing structure.(3)A magnetic fluid sealing structure is designed to seal water,including the selection of magnetic liquids,the design of pole shoes,permanent magnets,water baffles and back impellers.Use ANSYS to simulate the static magnetic field of the seal structure,and analyze the rationality of the magnetic circuit structure in the seal structure.the influence of the seal gap and the pole tooth width on the theoretical pressure resistance are analyzed,and the theoretical pressure value of the seal structure is calculated.(4)Combined with FLUENT and ANSYS,a unidirectional magnetic flow coupling method for simulating the flow of magnetic fluid in the sealing gap is designed.The multiphase flow model in computational fluid dynamics is used to simulate the leakage process of multi-pole tooth sealing water.The pressure transfer characteristics of the sealing water,the status of the two-phase interface when the water baffle is installed and the effect of the front back impeller on the sealing pressure are analyzed.Figure 61,table 8,reference 71.