Abstract
Like any other turbomachinery, it is essential that the hydraulic behavior and performance of mixed-flow pumps are evaluated way in advance prior to manufacturing. Pump performance relies heavily on the proper design of the intake structure. Intake structures should be accurately designed in order to minimize and avoid unnecessary swirl and vortex formations. Ensuring the optimum performance condition as well as predicting how a particular intake structure affects the efficiency of the pump often requires either physical model studies or theoretical evaluations. Unfortunately, physical models are costly, time-consuming, and site-specific. Conversely, design and performance predictions using a theoretical approach merely gives performance values or parameters, which are usually unable to determine the root cause of poor pump performance. This study evaluates the viability of using Computational Fluid Dynamics (CFD) as an alternative tool for pump designers and engineers in evaluating pump performance. A procedure for conducting CFD simulations to verify pump characteristics such as head, efficiency, and flow as an aid for preliminary pump design is presented. Afterwards, a multiphase simulation using the VOF approach is applied to compare the fluid dynamics between four different pump intake structures. A full-sized CFD model of the pump sump complete with the pump’s active components was used for the intake structure analysis in order to avoid scaling issues encountered during the reduced-scale physical model test. The results provided a clear illustration of the hydraulic phenomena and characteristic curves of the pump. A performance drop in terms of reduction in TDH was predicted across the various intake structure designs. The CFD simulation of intake structure provided a clear insight on the varying degree of swirl, flow circulation, and effect on pump efficiency between all four cases.
Highlights
A few of the specific hydraulic conditions that greatly affect the performance of any pump are swirl, vortices, and circulation
This paper presented numerical solutions to investigate the hydraulic performance of mixed flow submersible pumps under varying pump intake geometry and conditions
Afterwards, Computational Fluid Dynamics (CFD) simulations of a full-scale pump and intake structure were conducted to predict the formation of free-surface and submerged vortices during operation
Summary
A few of the specific hydraulic conditions that greatly affect the performance of any pump are swirl, vortices, and circulation. Aside from the numerous geometric parameters involved, the hydraulic conditions present in any pump are complex, and the physics of which are not fully understood It is for this reason that most pump engineers often rely on designs based on rule-of-thumb or standards established from previously proven designs. While there are numerous numerical and experimental studies concerning vortex prediction and flow phenomena in pump intake structures [4,5,6], most do not consider any impeller-induced flow This is because most physical model experiments do not include the impeller geometry in the scale model. No specific code and test procedure are established in conducting a reduced-scale hydraulic model test that incorporates the pump geometry to the model In this regard, this study presents a methodology to evaluate both pump and intake structure performance using CFD. Energies 2021, 14, 5082 focus is on a method that would result in reduced computational efforts in order to merit its use as an engineering design tool
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