Research on the Law of Head Loss of Jet Pumps in the Cavitation State

Abstract

Liquid flow is subject to head loss because of viscous force, surface tension, friction force, and so on. Part of the energy is irreversibly converted into heat, which then dissipates into the environment. Head loss intensifies in the turbulent state. At present, few studies explore the law of head loss caused by secondary flow, cavitation intensity, and turbulence intensity. In this study, the head losses in different sections of a jet pump were studied by controlling the cavitation number σ, the secondary flow rate Q s , and the inlet pressure p i . The experimental results were analyzed with the aid of computational fluid dynamics. The results show that an increase in Q s can weaken the variations of Q s and suction pressure p s in the transitional stage of cavitation. Besides, σ, Q s , and p i influence head loss to varying extents. Cavitation intensity and turbulence intensity are the main factors for head loss and jet temperature difference. In particular, the influence of Q s on head loss provides guidance both for reducing the energy loss of the quantitative adding device and jet aerator and for expanding the stable adding range of the jet. More importantly, the main factors of energy loss caused by jet cavitation were analyzed in detail, which can effectively facilitate the pipeline design to reduce the local and frictional head loss.

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“…However, it also leads to a great head loss in the capillary network. 47,48 In this study, the change in microcirculation perfusion was more apparent in hypertensive patients during the diastolic period. Metabolic abnormalities and metabolic syndrome are closely associated with hypertension severity.…”

Study on the Unsteady Characteristics and Radial Force of a Single-Channel Centrifugal Pump

“…The results showed that the CFD calculation of the flow in a single-channel centrifugal pump should adopt the unsteady method, and the low-pressure area of the outlet annulus of the impeller is located upstream of the outlet edge of the blade and close to the outlet edge. Gan et al 11 (secondary flow rate) can weaken the variations of Qs and suction pressure ps in the transitional stage of cavitation. Pei et al 12,13 studied the pressure pulsation phenomenon of a single-channel centrifugal pump under different working conditions.…”

“…The results showed that the CFD calculation of the flow in a single-channel centrifugal pump should adopt the unsteady method, and the low-pressure area of the outlet annulus of the impeller is located upstream of the outlet edge of the blade and close to the outlet edge. Gan et al 11 studied the head losses in different parts of a jet pump. The results show that an increase in Qs (secondary flow rate) can weaken the variations of Qs and suction pressure ps in the transitional stage of cavitation.…”