Cavitation is a detrimental phenomenon in hydraulic machinery, adversely impacting its performance, inducing vibration and noise, and leading to corrosion damage of overflow components. Centrifugal pump internal cavitation will lead to severe vibration and noise, and not only will the performance of hydraulic machinery be adversely affected but the impact generated by the collapse of the vacuole will also cause damage to the impeller wall structure, seriously affecting the safety of the equipment’s operation. To prevent the generation and development of internal cavitation in centrifugal pumps, to prevent the hydraulic machinery from being in a state of cavitation for a long time, to avoid the failure of the unit, and to realize the predictive maintenance of centrifugal pumps, therefore, it is of great significance to research the methods for monitoring the cavitation of hydraulic machinery and the methods for suppressing the cavitation. This paper comprehensively describes the centrifugal pump cavitation mechanism and associated hazards. It also discusses the current state of centrifugal pump cavitation monitoring methods, including commonly used approaches such as the flow-head method, high-speed photography, pressure pulsation method, acoustic emission method, and vibration method. A comparative analysis of these methods is presented. Additionally, the paper explores signal characterization methods for centrifugal pump cavitation, including time-domain feature extraction, frequency-domain feature extraction, and time–frequency-domain feature extraction. The current research status is elaborated upon. Moreover, the paper presents methods to mitigate cavitation and prevent its occurrence. Finally, it summarizes the ongoing research on identifying and determining the cavitation state in centrifugal pumps and offers insights into future research directions.

This study utilizes numerical calculations and experimental studies to analyze the cavitation characteristic law and performance of an agricultural irrigation axial flow pump with a specific rotational speed of 735 at 0.2Q_opt–1.2Q_opt operating conditions. The external characteristics and constant cavitation performance of the axial flow pump are simulated by using the $SST k-\omega$ turbulence model and $Zwart$ cavitation model, and the corresponding performance curves are obtained. The results show that the highest efficiency point occurs at the 1.1Q_opt condition, and the efficiency reaches 77.07%; the hump phenomenon occurs in the 0.6Q_opt–0.8Q_opt head curve, which is mainly caused by the fluid leakage due to the clearance at the top of the lobe. The critical cavitation margin (${NPSH}_3$) was determined to be 4.48 m, 4.36 m, and 4.09 m at 0.8Q_opt, 1.0Q_opt, and 1.2Q_opt flow conditions, respectively. These findings suggest that cavitation is more probable at lower flow conditions. In circumstances where the inlet pressure is lower than the critical pressure, the phenomenon of cavitation manifests predominantly within the low-pressure region of the suction surface of the blade. This region encompasses the inlet rim and the area surrounding the maximum thickness. This study provides a theoretical basis and practical reference for solving the cavitation problem of axial flow pumps.

Coating technology, as a common coating method, is widely used in many industrial fields, among which the mattress industry utilizes it to bond sponges to produce foam mattresses. The thickness of the coating on the sponge is crucial to the quality and performance of the mattress. Hence, this study took the CNCHK-10 high-performance intelligent sponge roller coating as a model; simulated the roller coating process under different viscosities and linear speeds using fluid simulation; analyzed the effects of different viscosities of the coating liquid and the linear speeds of the rollers on the thickness of the coating; and derived the relationships between the viscosity of the coating liquid and the linear speed of the rollers and the thickness of the coating. The relationship between the viscosity of the coating liquid and the linear speed of the roller and coating thickness was obtained. The results show that in the viscosity range of the glue, the viscosity is 1.5 Pa·s when the coating thickness is the smallest, and, at this time, the amount of glue is about 74.1927 g/m²; in the adjustment range of the roller linear speed, the linear speed is 20 m/min when the coating thickness is the smallest, and, at this time, the amount of glue is about 74.1931 g/m². The results of the study can be used for determining the coating process parameters for a reasonable selection and control to provide a theoretical basis.