| In this thesis,taking a high-pressure centrifugal pump as the research object,considering the effect of impeller clearance on the performance of centrifugal pump,the internal fluid flow control equation of centrifugal pump is established,and the finite element method and CFX software RNG k-ε are used Based on the turbulence model and the pressure-velocity based solver SIMPLE,the internal flow field and external characteristics of the centrifugal pump are simulated.The influence of the size and structure of the impeller ring on the overall performance of the centrifugal pump is explored from the perspective of the influence of the impeller ring on the pump performance.The main contents of this paper are as follows:1.The numerical analysis model of centrifugal pump is established.Firstly,the governing equations of the internal fluid of centrifugal pump are derived in detail,which provides a theoretical basis for the selection of RNG k-ε turbulence model and mechanical model.Solid Works 3D software is used to create the geometric model of the single-stage centrifugal pump to ensure the integrity of the assembly relationship of each flow passage component model;The centrifugal pump is meshed by ICEM CFD,and then imported into CFX software.The reasonable mechanical model and discrete method are selected to simulate the centrifugal pump with single and double volute structure.The internal flow field and external characteristic curves of the centrifugal pump are obtained and analyzed.2.Experimental research and verification.This thesis briefly introduces the test device and test method,and tests the double volute structure centrifugal pump on the test bench,compares the simulation results of single volute structure and double volute structure centrifugal pump with the test results of double volute structure centrifugal pump,and verifies the correctness of the mechanical model and solution setting method used in CFD numerical simulation.3.Research on the gap size of impeller seal ring.In order to study the influence of the gap size on the performance of centrifugal pump,combined with the existing gap value range of this type of centrifugal pump,a variety of gap values were set to study.Combined with relevant standards,this thesis will select the four clearance values of0.15 mm,0.30 mm,0.45 mm and 0.60 mm for modeling analysis,and use the mesh generation software to mesh the impeller ring model,and densify the key parts.After setting reasonable boundary conditions,CFX numerical simulation is carried out.It is found that the head and efficiency are greatly affected when the gap is 0.15 mm ～ 0.3mm,and the front gap is dominant.By comparing and analyzing the relevant results,it is determined that the reasonable gap value is 0.3mm.The gap length of the exit ring is set to be 25 mm,28 mm,30 mm,32 mm,35 mm and 40 mm.The pressure difference between the inlet and outlet sides of the gap and the development of turbulence in the gap are obtained.With the increase of the gap,the head and efficiency first increase and then decrease,and the head and efficiency reach the maximum at 30 mm,the results show that when the gap length is 30 mm,the leakage is the least,and the reasonable gap length is determined as 30 mm.Considering the effect of impeller gap value and gap length on the performance of centrifugal pump,the reasonable gap size is selected.4.Research on new seal ring structure staggered labyrinth ring.In order to get better sealing effect,based on the above research work,the flat ring,straight through labyrinth ring and staggered labyrinth ring are selected for numerical simulation.Through the comparative analysis of the results of three kinds of ring structure,it is concluded that the staggered labyrinth ring structure has a certain role in reducing the gap leakage and improving the volumetric efficiency of centrifugal pump. |
