Effect of gas quantity on two-phase flow characteristics of a mixed-flow pump

Fu, Qiang; Zhang, Fan; Wang, Xiuli

doi:10.1177/1687814016644578

Cited by 5 publications

(3 citation statements)

References 32 publications

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“…As a citation in some previous studies, these oscillations of bubbles can have a profound effect on the pressure fluctuations during pump operation. 39,40 From their results, the amplitude and magnitude of pressure fluctuations are sensitively affected by changes of the bubbles. The unsteady condition such as broad-band pressure fluctuation is proportional to the degree of cavitation and vapor volume fraction.…”

Section: Full-passage Analysismentioning

confidence: 99%

Numerical study on the cavitation phenomenon for the head drop and unsteady bubble patterns with a difference in the incidence angle of a mixed-flow pump

Kim

Yang

Suh

et al. 2020

Advances in Mechanical Engineering

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In this study, two types of mixed-flow pump models exhibiting different suction performances were investigated to understand the cavitation characteristics of head drop gradients due to the decrease in inlet pressure. Both models were designed with the same specifications except for the shroud inlet blade angle and inlet radius which directly affect the incidence angle. The steady- and unsteady-state analyses were performed using ANSYS CFX, and the results of both models were compared. Bubble generation and patterns were systemically represented at the design flow rate to observe their influence on suction performance. Furthermore, experimental tests were performed to validate the numerical results. From the results, the head drop gradient can determine the suction performance of mixed-flow pumps. The amount and shape of the bubbles concerning the suction performance of a mixed-flow pump exhibit significant differences with the changes in time and inlet pressure. The patterns of generated bubble are not stable even for each blade.

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Section: Full-passage Analysismentioning

confidence: 99%

Numerical study on the cavitation phenomenon for the head drop and unsteady bubble patterns with a difference in the incidence angle of a mixed-flow pump

Kim

Yang

Suh

et al. 2020

Advances in Mechanical Engineering

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“…However, where the inlet pressure is further reduced, the pressure fluctuation at r ¼ 0.41 is less than that of r ¼ 0.78, whereas the amount of the generated vapor for type B was larger at r ¼ 0.41 than r ¼ 0.78 as shown in Figures 9(d) and (e) and 14. The previous studies 58,59 had confirmed that the amount of vapor increases as the inlet pressure decreases, and the pressure fluctuation occurs gradually with the generated vapor considerably in the cavitation state. Based on the above results of this study, the correlation between the stability of internal flow and pressure fluctuation with the development of vapor seems to be somewhat reasonable, but it is further confirmed that the correlation is not perfectly proportional especially in severe cavitation state.…”

Section: Pressure Fluctuationmentioning

confidence: 82%

Effect of incidence angle on cavity blockage and flow stability in the net positive suction head drop of mixed-flow pumps

Kim

Lee

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part C:

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The cavitation is an inevitable factor in pumps used in the whole industry, which is a major cause of energy loss and mechanical breakdown. In this study, the cavitation phenomena at the design flow rate were numerically analyzed for two pumps with different incidence angles. The design flow rate for both models was located near the best efficiency point (BEP). The incidence angle was determined with the impeller inlet diameter and the blade angle. A pump with a smaller incidence angle consistently showed a stable flow pattern as the inlet pressure decreased, whereas a pump with a larger incidence angle contained non-uniform flow streamlines despite a very small amount of the generated cavities. The flow pattern at the impeller inlet was handled by the shape and thickness of the generated cavities which could act as an additional blockage in the pumps. The inception and growth of the cavity with a decrease of inlet pressure were also inferred, which was specifically quantified as the blockage ratio. A pump with a larger incidence angle performed poor cavitation characteristics and obtained the pressure fluctuation and cavity oscillation. The magnitude of pressure fluctuation was indicated using the fast Fourier transform (FFT) analysis. The experimental tests were performed on both pumps to validate the numerical results.

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“…With technology advancements, the two-phase centrifugal pump studies began to include computer simulations using finite element methods. Fu et al [19] presented a 3D model of a centrifugal pump in 2016. The elements of a centrifugal pump assembly were modeled in a drafting software and was imported into a finite element method (FEM) program.…”

Section: Introductionmentioning

confidence: 99%

Centrifugal Pump Monitoring and Determination of Pump Characteristic Curves Using Experimental and Analytical Solutions

et al. 2018

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Centrifugal pumps are widely used in the industry, especially in the oil and gas sector for fluids transport. Classically, these are designed to transfer single phase fluids (e.g., water) at high flow rates and relatively low pressures when compared with other pump types. As part of their constructive feature, centrifugal pumps rely on seals to prevent air entrapment into the rotor during its normal operation. Although this is a constructive feature, water should pass through the pump inlet even when the inlet manifold is damaged. Modern pumps are integrated in pumping units which consist of a drive (normally electric motor), a transmission (when needed), an electronic package (for monitoring and control), and the pump itself. The unit also has intake and outlet manifolds equipped with valves. Modern systems also include electronic components to measure and monitor pump working parameters such as pressure, temperature, etc. Equipment monitoring devices (vibration sensors, microphones) are installed on modern pumping units to help users evaluate the state of the machinery and detect deviations from the normal working condition. This paper addresses the influence of air-water two-phase mixture on the characteristic curve of a centrifugal pump; pump vibration in operation at various flow rates under these conditions; the possibilities of using the results of experimental investigations in the numerical simulations for design and training purposes, and the possibility of using vibration and sound analysis to detect changes in the equipment working condition. Conclusions show that vibration analysis provides accurate information about the pump's functional state and the pumping process. Moreover, the acoustic emission also enables the evaluation of the pump status, but needs further improvements to better capture and isolate the usable sounds from the environment.Processes 2018, 6, 18 2 of 15 refers to the difficulty of finding a general analytical model that explains the changes of the pump characteristic curve [3,6].The development in materials and pump construction have led to an increased life time and better reliability of the products. The pump application may limit the access of personnel for a thorough visual pump inspection, so that under these conditions, the use of non-intrusive sensors can replace humans for detecting pump failure. Sometimes, air entrapment does not necessarily lead to a major failure, hence the pump may work under two-phase flow until a replacement/solution is found. However, as the pump characteristic is changing, the control system needs to know how to adjust the pumping parameters accordingly, so that the pump runs under safe conditions. This paper shows the concept of how the pump characteristic curves transform from the normal state to the conditions of circulating a two-phase mixture. Several papers have shown and demonstrated the ability of vibrations measurement as an effective solution to identify improper machine state (such as valve opening or pump vibrations) [8][9][10][11][12...

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Effect of gas quantity on two-phase flow characteristics of a mixed-flow pump

Cited by 5 publications

References 32 publications

Numerical study on the cavitation phenomenon for the head drop and unsteady bubble patterns with a difference in the incidence angle of a mixed-flow pump

Numerical study on the cavitation phenomenon for the head drop and unsteady bubble patterns with a difference in the incidence angle of a mixed-flow pump

Effect of incidence angle on cavity blockage and flow stability in the net positive suction head drop of mixed-flow pumps

Centrifugal Pump Monitoring and Determination of Pump Characteristic Curves Using Experimental and Analytical Solutions

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