Large Eddy Simulations of cavitating tip vortex flows

Asnaghi, Abolfazl; Svennberg, Urban; Bensow, Rickard

doi:10.1016/j.oceaneng.2019.106703

Cited by 67 publications

(41 citation statements)

References 90 publications

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“…The 'window of opportunity' for inception for this case is smaller due the presence of stronger nuclei that require higher tensions to activate, hence a greater clustering of data points about what is presumably the location of minimum vortex pressure. The location of the peak shows agreement with the location of minimum pressure in the tip vortex of an elliptical hydrofoil, which has been found to be 0.125c downstream of the tip [9,4]. For both nuclei populations, inception events were detected up to 0.02c upstream of the tip.…”

Section: Resultssupporting

confidence: 80%

“…The influence of TVC inception location on cavity dynamics and acoustics is of interest as the streamwise variation of the vortex core pressure affects TVC behaviour. The minimum pressure occurs approximately 0.125c downstream of the tip for elliptical hydrofoils, where c is the chord length [9,4]. However, since inception could potentially occur at any location in the flow where the pressure is below vapour pressure, the lo-cation of inception has been reported anywhere from 0.05c upstream to 2c downstream of elliptical hydrofoil tips [12,16,2].…”

Section: Introductionmentioning

confidence: 99%

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Nucleation Effects on Tip Vortex Cavitation Inception Location

Khoo¹,

Venning²,

Pearce³

et al. 2020

Australasian Fluid Mechanics Conference (AFMC)

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Nuclei, or microbubble, populations are inextricably linked to tip vortex cavitation (TVC) inception and dynamics. In order to gain a better quantitative understanding of this relationship, high-speed video measurements were taken in a cavitation tunnel of TVC inception locations about an elliptical hydrofoil in flows with mono-and polydisperse injected nuclei populations.Sample sizes of O(1000) were acquired. For both populations, inception occurred between 0.02 chord lengths upstream of the hydrofoil tip and about 2.1 chord lengths downstream along the cavity trajectory. However, inception location distribution varied significantly with nuclei population. This is explained by the higher concentrations of weaker nuclei in the monodisperse case, which increases the distance along the vortex within which nuclei are susceptible to cavitation. These results provide the foundation for studies on TVC dynamics and acoustics.

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Section: Resultssupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Nucleation Effects on Tip Vortex Cavitation Inception Location

Khoo¹,

Venning²,

Pearce³

et al. 2020

Australasian Fluid Mechanics Conference (AFMC)

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“…Substantial efforts have been made to develop theoretical and numerical models for the roll-up process of trailing wingtip vortices [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] . The bulk of experimental investigations, largely required for the investigation of vortex dynamics and numerical validation, have been either qualitative in nature or directed toward tracking the mean tangential/axial velocities of the trailing vortex as a function of downstream range.…”

mentioning

confidence: 99%

Wingtip vortex structure in the near-field of swept-tapered wings

2020

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Wingtip vortices are an important phenomenon in fluid dynamics due to their complex and negative impacts. Despite numerous studies, the current understanding of the inner vortex is very limited, thus a basis for the design of effective wingtip geometry and vortex manipulation is narrow. This work examines the structure of the trailing vortex shed from a swept-tapered wing; analogous to a commercial aircraft topology. Stereoscopic particle imaging velocimetry (sPIV) has been utilised to compare the vortex structure and development through several angles of attack at various downstream stations for a fixed Reynolds number (Re = 1.5 × 10 6). After correcting for vortex meander, through helicity-based spatial localisation of the vortex core, relationships between the vortex core velocity/vorticity fields, core shape, and turbulent properties have been examined. Subsequently, the vortex is found to exhibit a layered structure with slow linear rates of dissipation indicative of laminar diffusion mechanisms: despite being a turbulent vortex. The turbulent kinetic energy distribution in the vortex signals that relaminarisation of the inner core occurs. Consideration of the streamline curvature around the core, via examination of the local Richardson number, indicated that a laminar core structure had formed within which large scale turbulent eddies could not contribute to the turbulent diffusion of vorticity away from the core. The normalised circulation within the vortex core has been shown to exhibit self-similar behaviour typical of fully developed axisymmetric vortices.

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“…Di Felice et al. 2009; Liefvendahl 2010; Liefvendahl, Felli & Tröeng 2010; Lu, Bensow & Bark 2014; Balaras, Schroeder & Posa 2015; Asnaghi, Svennberg & Bensow 2018, 2020; Posa et al. 2018, 2019 b ), but to the best of our knowledge, none for propellers interacting with downstream hydrofoils, probably due to cost considerations.…”

Section: Introductionmentioning

confidence: 85%