Background nuclei measurements and implications for cavitation inception in hydrodynamic test facilities

Venning, James A.; Khoo, MT; Pearce, BW; Brandner, PA

doi:10.1007/s00348-018-2520-5

Cited by 27 publications

(32 citation statements)

References 7 publications

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“…The medium sized tunnel contains 365 m 3 of demineralised water. While there is a permanent background nuclei population present in the water, these are of sufficiently high strength and sparsity to be considered inactive in this flow (Venning et al 2018c). The circuit architecture has been developed for continuous elimination of nuclei achieved through a combination of coalescence/gravity separation in a downstream tank and dissolution via extended residence in a resorber (Brandner 2018).…”

Section: Experimental Overviewmentioning

confidence: 99%

The influence of fluid–structure interaction on cloud cavitation about a stiff hydrofoil. Part 1.

et al. 2020

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Section: Experimental Overviewmentioning

confidence: 99%

The influence of fluid–structure interaction on cloud cavitation about a stiff hydrofoil. Part 1.

et al. 2020

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“…However, there are other sources of cavitation nuclei in practical flows for which much less is known both in oceans, where there are organic and other impurities (Stramski et al, 2004), or test facilities where there may be less impurities. Venning et al (2018) showed that the water in the AMC cavitation tunnel, where no microbubbles generated by cavitation or artificial nuclei seeding were present, is susceptible to cavitation at all tensions given sufficiently long sampling time. It was also observed that the relationship between concentration and critical tension is a power law.…”

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confidence: 99%

Natural nuclei population dynamics in cavitation tunnels

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Nuclei, or microbubble, populations control the inception and dynamics of cavitation. It is therefore important to quantify distributions in cavitation test facilities to rigorously model nucleation dynamics. Measurements of natural nuclei population dynamics were made in two test facilities in Australia and Japan via mechanical activation using a Cavitation Susceptibility Meter (CSM). A range of tunnel operating parameters, including pressure, velocity and dissolved oxygen (DO) content, were investigated. The DO saturation condition upstream of the test section is found to provide a threshold as to whether the population is affected by DO in the Australian test facility. Historical trends in the population are quantified, indicating that regular monitoring is required. Variation of the population around the Australian cavitation tunnel circuit was studied by varying the water sampling location. Provided the water remains undersaturated, as defined above, the natural nuclei population in the test-section can be measured by sampling from the lower-limb resorber. Comparisons are made between test facilities in Australia, Japan and other countries, as well as environmental waters, using different measurement techniques. Optical and acoustic methods show microbubbles in the size range of 10 to 100 µm typical of those used to

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“…The CRL tunnel natural or background nuclei population has been measured using CSM [18] since these are too small and sparse to be measured optically. This population has been found to obey a power law relationship between cumulative concentration and critical pressure and to be invariant of normal operating conditions [19]. The results shown have been converted to equivalent bubble size from bubble equilibrium theory.…”

Section: Microbubble Measurement Techniquesmentioning

confidence: 96%

Microbubbles and Cavitation: Microscales to Macroscales

Brandner¹

2018

Proceedings of the 10th International Symposium on Cavitation (CAV2018)

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Microbubbles are systemic to cavitation physics. They are present in all practical liquid flows, they provide nuclei for inception, their dynamics play a role in many of the phenomena and processes involved in cavitation and ultimately they are generated by cavitation collapse and condensation. Various techniques for the generation, measurement and dispersion of microbubbles for experimental modelling of cavitation nucleation and dynamics in hydrodynamics test facilities are presented. Controlled generation of microbubbles are also required for development and calibration of optical measurement techniques and for flow diagnostics. Several techniques for generation of mono-, and poly-disperse microbubble populations in the size range 1 to 100 microns are discussed. Microbubble concentrations generated by devices or from cavitation itself vary from 1000 bubbles per cubic cm down to 0.01, in addition to the size range, necessitating the use of several methods for measurement of both size range and concentration. Experimental results demonstrating the influence of nuclei populations on stable and unstable cavitation in canonical flows about spheres and hydrofoils are presented. Nuclei populations affect shedding mechanisms and modes, spectral content, amplitudes of forces and microbubble content in downstream wakes.

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Background nuclei measurements and implications for cavitation inception in hydrodynamic test facilities

Cited by 27 publications

References 7 publications

The influence of fluid–structure interaction on cloud cavitation about a stiff hydrofoil. Part 1.

The influence of fluid–structure interaction on cloud cavitation about a stiff hydrofoil. Part 1.

Natural nuclei population dynamics in cavitation tunnels

Microbubbles and Cavitation: Microscales to Macroscales

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