A Generalized Approach on Equilibrium Theory of Cavitation Nuclei in Liquid-Gas Solutions

Tsai, Jing‐Fa; Chen, Yih‐Nan

doi:10.1115/1.2909432

Cited by 3 publications

(4 citation statements)

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“…This is justified by taking into account that cavitation begins with nuclei diameters within the range 10 À7 À10 À5 m [20,21], which grow explosively as they pass through regions where the pressure drops below the vapor pressure, and that, for gaseous cavitation, growth is limited by molecular diffusion timescales, being therefore much slower than aeration. The total volume of dissolved air is given by the Bunsen coefficient, which represents the volume of gas to volume of fluid ratio at atmospheric conditions and takes the value of 0.09 for oil.…”

Section: Selection Of the Cavitation Modelmentioning

confidence: 99%

Numerical Analysis of External Gear Pumps Including Cavitation

Campo

Castilla

Raush

et al. 2012

Journal of Fluids Engineering

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Hydraulic machines are faced with increasingly severe performance requirements. The need to design smaller and more powerful machines rotating at higher speeds in order to provide increasing efficiencies has to face a major limitation: cavitation. The problem is inherently three-dimensional, due to the axial clearances, the relief and circumferential grooves, and to the circular pipes through which the fluid enters and exits the pump. A simplified two-dimensional numerical approach by means of computational fluid dynamics (CFD) has been developed for studying the effect of cavitation in the volumetric efficiency of external gear pumps. The assumptions employed prevent from predicting realistic values of the volumetric efficiency, but show to be valid to understand the complex flow patterns that take place inside the pump and to study the influence of cavitation on volumetric efficiency. A method for simulating the contact between solid boundaries by imposing changes in viscosity has been developed. Experiments of unsteady cavitation in water and oil performed by other authors have been numerically reproduced using different cavitation models in order to select the most appropriate one and to adjust its parameters. The influence of the rotational speed of the pump has been analyzed. Cavitation in the suction chamber very effectively damps the water hammer associated to the sudden change of the contact point position at the end of the gearing cycle. At high rotational speeds, the volume of air becomes more stable, reducing the flow irregularity. When cavitation takes place at the meshing region downstream from the contact point, the volume of air that appears acts as a virtual second contact point, increasing the volumetric efficiency of the pump.

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Section: Selection Of the Cavitation Modelmentioning

confidence: 99%

Numerical Analysis of External Gear Pumps Including Cavitation

Campo

Castilla

Raush

et al. 2012

Journal of Fluids Engineering

View full text Add to dashboard Cite

show abstract

“…Not all previous linearized equations have their counterpart in defining the steady system which is much more simpler. It involves the following equations, which were already proposed by Cha (1983) and Tsai and Chen (1990) Where l{.is the molar gas constant with the value 8.314 J.K-l.mol-l .…”

Section: Equilibrium States and Bifurcating Statesmentioning

confidence: 99%

“…The corresponding thermodynamic potentials are the Gibbs free energy, the Helmholtz free energy and the availability (Muller, 1985). Tsai and Chen (1990) showed moreover that the constraints adopted in the two first studies implies unphysical consequences and must be discarded.…”

Section: Introductionmentioning

confidence: 98%