| With the social progress and technical development, pumps are expected to have higher efficiency, wider range of stable operation and lower noise. Meanwhile, with fast development of computer technology and mature of CFD methods, CFD plays an increasing important role in the design and research of advanced pumps. The researches in this dissertation were accordingly carried out on the development of a CFD solver, the 3D numerical simulation of unsteady turbulent flow in double-channle pump and the PIV measurement of the unsteady flow in the double-channel pump impeller. The main work and achievements include:1. Based on differential equation method, a grid generation code was developed for the 3-D body-fitted structured grids. Poisson equation with additional source terms was employed, and sourc terms P,Q,R were built according to Thompson and Sorenson's thought by interpolation of exponential function. With this code, grids were generated for the double-channel impeller and volute, which had great quality to satisfy the precision request of inner flow calculation within pumps. The grids' size would be personally controlled, the grid lines were orthogonal to boundary walls and it was convenient to feed in turbulent wall boundary conditions. After appropriate adjustment, the code can also be used to generate the mesh of other irregular flow channel conveniently.2. A CFD solve package based on the solution of Reynolds-averaged Navier-Stokes equations was developed for the numerical simulation of laminar or turbulent, compressible or imcompressible three-dimensional flow fields with or without rotating. User-friend operation interface was also developed based on Visual FORTRAN platform. The pressure-correction technique on a non-staggered grid arrangement was employed with the Rhie and Chow scheme to remove the related pressure oscillations. For the simulation of the turbulence effects the standard two-equation k-εmodel and k-εmodel modified by rotation and curvature were available for choice. Using this solver package, three flows were calculated, i.e., the flow in a 90°bend, the flow in the double-channel pump impeller and the flow in the double-channel pump volute. The reliability, accuracy, and flexibility of the developed solver was validated through these calculations.3. By FLUENT, the three dimensional unsteady turbulent flow was simulated within the double-channel pump using different flow models. The distributions of absolute velocity, relative velocity, static pressure, total pressure, turbulence kinetic energy and volume fraction of solid phase within the pump were obtained, which preliminary revealed the flow mechanism in double-channel pump. The solid-liquid two-phase flow field was comprehensively analyzed with different particle diameter and sandy volume fraction. The unsteady flow characteristics were discussed considering the interaction between the impeller and volute. It was mainly concluded that:(1) Under identical operating condition, the velocity distribution was different on different cross sections in the pump. The cross section near to the hub was affected more by the inlet whirlpool, thus the flow here was more turbulent and the velocity distribution was more disordered at the outlet. The cross section near to the shroud was affected less, thus the flow on this plane was more regular and the volcity distributed more uniformly at the outlet.(2) Under different operating conditions, the velocity and pressure distribution exhibited similar characteristics. However, with the increasing of flow rate, the relative velocity increased, the absolute velocity decreased and the total pressure difference between the inlet and outlet decreased. Under the design operating condition, the flow status was optimal for the double-channel pump.(3) In the solid-liquid two-phase flow field, the particle distribution was non-uniform. At the impeller inlet, the particles distributed uniformly, later solid particles tended to accumulate on pressure side and the shroud of the impeller. After entering the volute, few solid particles would directly go out of the volute, and a large number of solid particles collided with volute wall and exited after circling around the volute for several times. The inlet sandy volume fraction had less influence on the solid segregation effect, however, particles tended towards suction side at the condition of low sandy volume fraction. The particle diameter had more influence on the solid segregation effect, with the increasing of particle diameter, the particle distributed more non-uniformly, and the segregation became amplified. In the range of particle diameter and sandy volume fraction studied in this article, it could be concluded that pump head declined with the increase of sandy volume fraction, and particle diameter had less effect on pump head.(4) Due to the interaction between the impeller and volute, the flow in double-channel pump displayed different characteristics at different time. When the studied flow channel was near to the volute outlet, the velocity and pressure distribution was more regular. When the studied flow channel was far from the volute outlet, the flow discharged from impeller was blocked and backflow occurred. The static and total pressure distribution in the volute exhibited periodic variation according to the relative position of the flow channel to the tongue. Blade tails left obvious wake area on the total pressure contour.4. According to the special requirements for centrifugal pump PIV measurement, a PIV testing platform was established to measure the instantaneous velocity in the double-channel pump with different impeller design, i.e., the double-channel impeller and the two-blade impeller, under different working conditions. The measured absolute velocity fields were transfered to relative velocity fields by specially developed code. It was found that at design condition, the double-channel impeller had better flow pattern, smaller separation and vortex area than that of the two-blade impeller. It was also proved that the measured results showed great agreement with the calculated ones.
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