Investigation of internal flow characteristics in volute with varying inlet widths for low specific speed centrifugal pumps

As a vital pump component, the inlet width of volute is a key factor affecting the performance of the pump. In this paper, through the combination of numerical calculation and experimental verification, the influence of the volutes with different inlet widths on the pump performance and internal flow field distribution is carefully investigated when the cross-sectional area of volute remains almost the same. To this end, three volutes with different inlet widths are selected and simulated by the computational fluid dynamics software which is based on the Navier–Stoke equation of three-dimensional stable flow. Moreover, the accuracy of the numerical method is verified by comparing with the experimental results. The pump performance of the volutes with three inlet widths is specially compared and analyzed. We find that when the volute is of the similar cross-sectional area, with the increase of the inlet width, both head and efficiency of the pump are enhanced, while the internal pressure and flow field distribution of the pump are improved as well. Furthermore, through the analysis of entropy production rate in different regions, we observe that the entropy production rate with an inlet width of 3 mm is the smallest under the design conditions, and the entropy production rate with an inlet width of 4.25 mm is the largest. Therefore, for properly determining the inlet width, it is necessary to jointly consider several factors (such as entropy production rate and pressure distribution) to obtain the optimal hydraulic performance.