Anti-Cavitation Design of the Symmetric Leading-Edge Shape of Mixed-Flow Pump Impeller Blades

Abstract

Mixed-flow pumps compromise large flow rate and high head in fluid transferring. Long-axis mixed-flow pumps with radial–axial “spacing” guide vanes are usually installed deeply under water and suffer strong cavitation due to strong environmental pressure drops. In this case, a strategy combining the Diffusion-Angle Integral Design method, the Genetic Algorithm, and the Computational Fluid Dynamics method was used for optimizing the mixed-flow pump impeller. The Diffusion-Angle Integral Design method was used to parameterize the leading-edge geometry. The Genetic Algorithm was used to search for the optimal sample. The Computational Fluid Dynamics method was used for predicting the cavitation performance and head–efficiency performance of all the samples. The optimization designs quickly converged and got an optimal sample. This had an increased value for the minimum pressure coefficient, especially under off-design conditions. The sudden pressure drop around the leading-edge was weakened. The cavitation performance within the 0.5–1.2 Qd flow rate range, especially within the 0.62–0.78 Qd and 1.08–1.20 Qd ranges, was improved. The head and hydraulic efficiency was numerically checked without obvious change. This provided a good reference for optimizing the cavitation or other performances of bladed pumps.

Flow Characteristic Analysis of the Impeller Inlet Diameter in a Double-Suction Pump

“…In this paper, the outer diameter (d 2 ) and width (b 2 ) of the impeller's outlet, as well as the exit blade angle, were kept constant across all cases. The impeller inlet has the most influence on the stability of the pump and cavitation [22][23][24][25][26][27]. Therefore, this study fixed the diameter of the impeller's hub (d 1i ) and varied the shroud size (d 1a ) at the inlet as described earlier, aiming to understand how the ratio of the diameter of the hub to the diameter of the shroud at the impeller inlet affects the pump's performance and stability.…”

“…There are numerous preliminary studies investigating the recirculation phenomenon at the impeller inlet and pump cavitation. D. Zhu [22], Sano [23], Balasubramanian [24], and Dönmez, A. H. [25] mainly researched cavitation based on the leading edge shape of the impeller inlet using CFD and experimental methods. Luo [26] conducted research on the effects of the starting point and the size of the impeller's leading edge, and Shukla [27] carried out both experimental and numerical studies on the cavitation performance related to variations in the inlet diameter.…”

The Cavitation-Induced Pressure Fluctuations in a Mixed-Flow Pump under Impeller Inflow Distortion

“…Compared with bell-shaped and elbow-shaped inlet conduits, dustpan-shaped inlet conduits can ensure the flow pattern of impeller inflow under low excavation depth [4,5] (which can reduce civil costs); therefore, its application is becoming more and more extensive. However, cavitationinduced pressure fluctuation has always restricted improvement in the operation stability of mixed-flow pumps [6][7][8]. In addition, the particularity of the dustpan-shaped inlet conduit could cause impeller inflow distortion, which would further strengthen the cavitationinduced pressure fluctuation of mixed flow pump.…”

Multi-objective optimization of a high efficiency and suction performance for mixed-flow pump impeller

“…The common numerical optimization in pumps suppressed the cavitation phenomenon by controlling main rotating components, especially at the meridional plane and blade angles (Liu et al, 2013;Visser, Dijkers, de Woerd, & H, 2000). Moreover, pump head and efficiency were also sensitive to shape parameters (Tao, Xiao, & Wang, 2018;Zhu, Tao, & Xiao, 2019). Therefore, when designing a high-performance impeller, both the suction performance and the hydraulic performance must be considered, thereby increasing the complexity of work.…”