Influence of pump rotational speed on novel cavitation dynamics response and hydraulic performance of a centrifugal pump investigation

Centrifugal pumps constitute one of the most extensively utilized hydraulic machines design across industrial, commercial, agricultural, and domestic sectors because of their robust construction, operational reliability, and high hydraulic efficiency. Their primary function is to convert mechanical energy supplied by the driving shaft into hydraulic energy, thereby increasing the pressure and kinetic energy of the working fluid to facilitate its transport throughout a flow system design. Owing to the wide range of operating conditions encountered in practical applications, the geometric configuration, impeller dimensions, rotational speed, and internal hydraulic components of centrifugal pumps are designed to satisfy specific performance requirements. Among the various factors limiting pump performance and service life, cavitation remains one of the most critical hydraulic phenomena. Cavitation is initiated when the local static pressure decreases below the saturation vapor pressure of the liquid, resulting in the formation of vapor cavities within the flow. In centrifugal pumps, this process is predominantly observed in the low-pressure region located at the impeller eye, particularly along the suction side near the leading edges of the impeller blades, where the highest flow acceleration produces the minimum pressure levels. The computational fluid dynamics (CFD) simulations demonstrate that vapor formation first appears at the impeller inlet in the vicinity of the blade leading edge, indicating the onset of cavitation within the eye region. As the fluid progresses through the rotating passages, the vapor structures expand and occupy a larger portion of the blade-to-blade channels, revealing the progressive development of cavitation throughout the impeller. The numerical predictions further indicate that increasing the impeller rotational speed significantly intensifies the cavitation process. Higher rotational speeds generate greater flow acceleration and consequently lower local pressures, promoting increased vapor generation and a corresponding enlargement of the vapor volume-fraction distribution within the impeller passages design. The different errors between the numerical and experimental results were around 7%. The rapid cavitation growth was further increasing the flow rate to 320–350 L/min.