Experimental investigation of flow and cavitation characteristics of a two-step throttle in water hydraulic valves

Liu, Y. S.; Huang, Yan; Li, Z. Y.

doi:10.1243/095765002760024881

Cited by 23 publications

(16 citation statements)

References 11 publications

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“…10 Schematic diagram of the testing apparatus Low cavitation in water hydraulic two-stage throttle poppet valve two-stage throttle valve with a low critical cavitation index level exhibits a better anti-cavitation capability than the single-stage throttle valve. This is consistent with the qualitative conclusions as drawn by Oshima et al [14] and Liu et al [15,16]. Indeed, the multi-stage throttles are beneficial for improving the system's anti-cavitation capability.…”

Section: Discussionsupporting

confidence: 91%

“…It was found that the discharge coefficient and the critical cavitation number for water poppet throttles were considerably different from those of oil ones, due to the high density and low viscosity of water. Recently, Liu et al [15,16] investigated experimentally the flow and cavitation characteristics of a two-stage throttle in water hydraulic system; they concluded that the two-stage throttle had stronger anti-cavitation capability than the single-stage one, and that the shape of seats also affected the anticavitation capability of the throttles. The cavitation choking appeared only when cavitation index was less than 0.4.…”

Section: Introductionmentioning

confidence: 99%

“…As an extension of Liu et al [15,16], this research will focus on the investigation of cavitation characteristics in the water hydraulic two-stage throttle poppet valve. This objective entails the following research tasks: (a) on the basis of the RNG k -1 turbulent model, numerical simulations will be conducted to investigate the pressure distribution inside the medium chamber located between the two throttles, (b) the effect of the passage area ratio of the two throttles and pressure between the two throttles on the anti-cavitation capability will be studied, (c) the design criteria of the two-stage throttle valve will be established for low-cavitation and noise, and (d) experimental validation will be performed through a custom-manufactured testing apparatus, to demonstrate applicability of the developed simulation approach and design criteria.…”

Section: Introductionmentioning

confidence: 99%

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Research on low cavitation in water hydraulic two-stage throttle poppet valve

Nie

Huang

et al. 2006

Proceedings of the Institution of Mechanical Engineers, Part E:

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Cavitation has important effects on the performances and lifespan of water hydraulic control valve, such as degrading efficiency, intense noise, and severe vibration. Two-stage throttle valve is a practicable configuration to mitigate cavitation, which is extensively used in water hydraulic pressure relief valves and throttle valves. The pressure distribution inside a medium chamber located between two throttles of a two-stage throttle valve is investigated through numerical simulations. The effects of the passage area ratio of the two throttles and the inlet and outlet pressures on the pressure inside the medium chamber are examined. The simulation results indicate that (a) the pressure inside the medium chamber is not constant, (b) the locations of maximum and minimum pressures inside the medium chamber are both fixed, which will not vary with the passage area ratio or the inlet and outlet pressures, and (c) the ratio of the pressure drop across the front throttle to the total pressure drop across the two-stage throttle valve is nearly constant. The critical cavitation index of the two-stage throttle valve is then established. A semiempirical design criterion is obtained for the water hydraulic two-stage throttle valve. The correlation between the critical cavitation index and the passage area ratio of the two throttles is investigated. Relevant validation experiments are conducted at a custom-manufactured testing apparatus. The experimental results are consistent with the simulated ones. Further analyses indicate that (a) the large backpressure can improve not only the anti-cavitation capability but also the total load rigidity of the water hydraulic twostage throttle valve, (b) an appropriate passage area ratio will be beneficial for improving the anti-cavitation capability of the water hydraulic two-stage throttle valve, and (c) the water hydraulic two-stage throttle valve with a passage area ratio of 0.6 would have the best anticavitation performance with the lowest risk of cavitation.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Research on low cavitation in water hydraulic two-stage throttle poppet valve

Nie

Huang

et al. 2006

Proceedings of the Institution of Mechanical Engineers, Part E:

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“…The results indicate that the anticavitation performance of the sharp-edged two-step throttle valve is better than the chamfer-edged one. 20 Furthermore, the pressure distribution of two-step throttle valve has been investigated through numerical simulation. The simulation results evidences that a high backpressure is beneficial for improving the properties of anticavitation.…”

Section: Introductionmentioning

confidence: 99%

New approach of suppressing cavitation in water hydraulic components

Zhang

Cao

Luo

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part C:

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Cavitation frequently appears in high pressure water hydraulic components and leads to serious hydraulic erosions and horrible hydrodynamic noises. In this paper, a novel approach of suppressing cavitation was proposed, inducing the outlet pressure back to the orifice to improve the pressure distribution of throttle valves. In order to realize this approach, an optimized throttle valve chamber structure was designed. After that, the anticavitation performance of the valve was investigated. A theoretical cavitation cloud model was built based on bubble dynamics. In order to solve the mathematic cavitation model, the velocity field and pressure distribution of the novel throttle valve were simulated through Computational Fluid Dynamics(CFD). Combining the simulation results, the mathematic cavitation cloud model was solved through numerical calculations. Moreover, new indexes estimating cavitation intensity were proposed scientifically to investigate cavitation phenomenon. Then, the comparison of the novel throttle valve (with an innovative valve chamber) and traditional throttle valve in anticavitation performance was conducted under different conditions. Finally, the experiment about anticavitation performance was completed on the test rig. The calculation and experiment results indicated that the approach, inducing the outlet pressure back to the orifice, was effective in suppressing cavitation.

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“…In particular, when a pressure shock occurs, it generates a large impact flow caused by the external load. This leads to a serious cavitation [13][14][15] phenomenon, poor reliability and unstable dynamic characteristics. These problems seriously affect the safety and reliability of the pilot operated check valve and associated system.…”

Section: Introductionmentioning

confidence: 99%

Multistage throttling characteristics of reverse direction impact of pilot operated check valve

Liu¹,

Zhao²

2016

J. vibroeng.

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The aim of this study was to improve the reverse impact characteristics of large-flow pilot operated check valves, meanwhile reduce oscillation, cavitation and unloading time. Three different main poppets were selected, and the impact pressure and flow were set as 30 MPa and 1000 L/min, respectively. The cavitation phenomenon was explored based on the analysis of gas-liquid two-phase flow by Fluent software, and then experimental verification was performed. Meanwhile, the dynamic characteristics of pilot operated check valves were analyzed by the impact test system. The simulation results showed that the fluid pressure clearly decreased while flowing through the poppet area. The sudden decrease of flow area at the orifice port of the poppet resulted in an increase in flow-velocity, because the cavitation area appears on the side of the main poppet. A stepped throttling structure could effectively reduce the cavitation area, preventing the generation of cavitation. The experimental results showed that the pressure oscillation of a stepped main poppet significantly reduced during the process of unloading, at 28.41 MPa; with a flow gradient of 4.86×105 L/min 2 ; unloading time significantly reduced, for 711 ms; indicating it opened more rapidly and dynamic characteristics was superior. It can be concluded that the stepped throttling structure could effectively reduce the pressure oscillation of a pilot operated check valve during the process of unloading, improve response speed, enhance the impact properties, and reduce cavitation. This verified the correctness of the simulation and the rationality of the cavitation index.

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Experimental investigation of flow and cavitation characteristics of a two-step throttle in water hydraulic valves

Cited by 23 publications

References 11 publications

Research on low cavitation in water hydraulic two-stage throttle poppet valve

Research on low cavitation in water hydraulic two-stage throttle poppet valve

New approach of suppressing cavitation in water hydraulic components

Multistage throttling characteristics of reverse direction impact of pilot operated check valve

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