Research On Wear-rings Of Centrifugal Pump Based On CFD Code

Wear-rings of impeller have great influence to the performance of centrifugal pumps. The existence of the clearance of wear-rings not only produces the capacity lose, but also changes the internal flowing structure of the pump, thus has an important influence to the performance of the whole machine, axial-force and radial-force. Because of its smaller size, and complicated inner flow, studies on wear-rings is difficult, former flow analysis considers the influence according to the experiment method mostly; but numerical simulation based on CFD code usually neglect the existence of the wear-rings, so the research on centrifugal pump including the wear-rings adopting numerical method has great significance..In this thesis, finite volume method solving three-dimensional Reynolds-averaged Navier-Stokes viscous partial differential equations is employed to study the internal flow field of whole system, which including different wear-rings, by using the commercial CFD code FLUENT. The hybrid structure/unstructured grid is adopted to mesh the complex computational domain. Standard two-equation k ?εturbulent model with standard wall functions is used to evaluate the turbulent diffusivity. The pressure-velocity coupling is solved using SIMPLE algorithm. The variety of the wear-rings is divided into three kinds: both front and back wear-ring change; only the front wear-ring changes while the back keeping constant; only the back wear-ring changes while the front keeping constant.Outer characteristic curves and inner flow structure under the three kinds of circumstances were compared, and the influence of the variety of the wear-rings to the whole machine's function, inner flow, axial-force and radial-force was analyzed. Studies show that, the function of the pump all descend by the accretion of the clearance of the wear-rings, among them, the biggest influence to the function of the pump is from both front and back wear-ring change, only the front wear-ring changes is the second and only the back wear-ring changes has a least influence. Axial-force enlarges with the clearances increase, analysis shows that the major influence to the axial-forcer is from the front wear-ring; radial-force changes little with the clearance of the wear-rings change.