Abstract
Vortex pumps have good non-clogging performance and are widely used in the fluid transportation of food, sewage treatment, and mineral and coal slurry transportation. In order to design and manufacture a vortex pump with good performance and establish a method of optimum design, we must master the internal flow rules of the pump. Based on the self-design vortex pump (32WB8-12) experiment, the discharge-pump head (qv-H), discharge-pump shaft power (qv-P), discharge-pump efficiency (qv-η), and discharge-critical net positive suction head (qv-NPSHc) curves are obtained, and the qv-NPSHc curve shows an opposite tendency compared with the centrifugal pump. With the mathematical model selected with respect to the optimal condition, the three-dimensional internal flow within the vortex pump has been numerically simulated by a renormalization group k-ε (RNG k-ε) turbulence model. The static pressure (ps) and velocity distribution of the impeller and the middle section of the volute at 0°, 90°, 180°, and 270° are obtained, and the performance curves have been fitted using a CFX-calculated energy parameter. It was illustrated that the velocity field is relatively disordered and the flow in the impeller region is of a forced vortex character. The flow in the volute is similar to that of the combined vortex with backflow, which is a non-axisymmetric unsteady flow with quite high turbulence intensity. These factors are the main reasons for the relatively low efficiency of the vortex pump. The measurement of flow field in volute with a five-hole probe was conducted, and it is demonstrated that the numerical results are in good agreement with the flow field measurement data. An upward pressure gradient forms in the portal area of the impeller, and it is confirmed that the lowest pressure point is located in the upper position of the impeller hub. It is revealed that for the vortex pump to have advanced suction and anti-cavitation performance, the lowest pressure in the pump should be −4 × 104 Pa and it should be located at the center of the vortex chamber cavity.
Highlights
If we present, if we compare the vortex pump with the centrifugal pump, the biggest disadvantage is the compare the vortex pump with the centrifugal pump, the biggest disadvantage is the low efficiency low efficiency of the vortex pump [4,5]
As long as verification of the numerical calculation of the numerical calculation results the vortex chamber flow field through comparative results of the vortex chamber flowoffield through comparative analysis reaches a certainanalysis level of reaches a certain level of precision, it can be extended to deduce that the numerical calculation precision, it can be extended to deduce that the numerical calculation of the internal flow fieldof ofthe the internal flow field of the whole vortex pump gives realistic results
In a small flow state, the qv -NPSHc curve of vortex pump is the opposite to the qv -NPSHc of the centrifugal pump, and NPSHc value is large, that is, the vortex pump has poor anti-cavitation
Summary
Ping Tan 1 , Yi Sha 1, *, Xiaobang Bai 2 , Dongming Tu 1 , Jien Ma 3,4,5, *, Wenjun Huang 3,4,5 and Youtong Fang 3,4,5. China Academy of West Region Development, Zhejiang University, Hangzhou 310027, China. Received: 17 September 2017; Accepted: 1 December 2017; Published: 7 December 2017
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