Analysis and Comparison of Two Kinds of Design Approaches for Volutes of Centrifugal Pump

Abstract

It is a commonly used method to design volutes for centrifugal pumps by applying statistical data. Different statistical analyses were performed by various pump technicians based on different pump samples and data-processing methodologies. When the performance parameters at the design point of a pump w given, differences in the geometrical parameters and hydraulic characteristics of the finalized volute may exist if different statistical data are applied in the volute design procedure. Two types of typical statistical data extensively used by engineers for volute design were described systematically. As the wetted perimeters of volute sections and volute inlet width are considered two key parameters that have a considerable impact on the hydraulic performance of pumps, one type of statistical data introduced a new shape of volute sections to reduce the wetted perimeter and friction area. In the second type of statistical data, the volute inlet width could be governed by designers to improve flow behavior at the volute entrance. To compare the energy-saving effects of the two types of volute design guidelines, the models of the wet parts of three pumps with different design flows and heads were established. Then, two-volute models were designed and manufactured for each impeller using two-volute statistical data, and the internal flow field of the three pumps under multiple working conditions was simulated using computational fluid dynamics (CFD) technology. The numerical results show that the head and efficiency can be improved using a shorter cross-section wet volute under the same impeller conditions. The influence of the wetted perimeters of the volute sections on the pump performances is more remarkable than that originating from the volute inlet width. The results of this research also show that the statistical data containing the above design principles should be promoted.