Some observations of tip-vortex cavitation

Arndt, Roger E. A.; Arakeri, V.H.; Handa, Hiroshi

doi:10.1017/s0022112091003026

Cited by 161 publications

(70 citation statements)

References 36 publications

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“…High-resolution measurements on the wing tip vortices have been performed in numerous other studies. Point-wise laser Doppler velocimetry was used on a stationary wing tip vortex, in a chronological order (Higuchi et al 1987;Arndt et al 1991;Arndt and Keller 1992;Fruman et al 1995;Boulon et al 1999). Later the same method was used to measure the flow field including the tip vortices trailing a rotating propeller (Felli et al 2009Felli and Falchi 2011).…”

Section: Introductionmentioning

confidence: 99%

Flow field measurement around vortex cavitation

2015

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stage. These involve the smooth transport of vapor into the tip vortex, leading harmful implosions away from the propeller surface. The tip vortex cavity dynamics are not directly related to the propeller rotation rate. The excitation of this cavity often leads to high amplitude broadband pressure fluctuations between the fourth and seventh blade rate frequency (Wijngaarden et al. 2005).To better understand the sound production from vortex cavitation, a model for the waves on a tip vortex cavity was developed and was shown to be able to describe the interface dynamics in detail (Pennings et al. 2015). As a result, a condition could be predicted where a cavity resonance frequency could be amplified to produce high amplitude sound, as reported by Maines and Arndt (1997).The part that remains to be validated is a vortex model for the cavity size and cavity angular velocity. It has been shown that a Lamb-Oseen vortex model poorly estimates the cavity size as a function of cavitation number (Pennings et al. 2015). It is possible that overestimation of the vortex peak azimuthal velocity could have led to an overestimation of the cavity size. The main goal of the present study was to configure a simple low-order vortex model, to serve as an input into a vortex cavity wave dynamics model, to describe the tip vortex resonance frequency. It is based on the following steps.1. Model the tip vortex velocity field without cavitation (further referred to as wetted vortex) 2. Model the cavity size as a function of cavitation number based on wetted vortex properties 3. Show the difference in velocity field around a wetted and cavitating vortex 4. Obtain the cavity angular velocity value that gives the best correlation to the tip vortex cavity resonance frequency Abstract Models for the center frequency of cavitatingvortex induced pressure-fluctuations, in a flow around propellers, require knowledge of the vortex strength and vapor cavity size. For this purpose, stereoscopic particle image velocimetry (PIV) measurements were taken downstream of a fixed half-wing model. A high spatial resolution is required and was obtained via correlation averaging. This reduces the interrogation area size by a factor of 2-8, with respect to conventional PIV measurements. Vortex wandering was accounted for by selecting PIV images for a given vortex position, yielding sufficient data to obtain statistically converged and accurate results, both with and without a vapor-filled vortex core. Based on these results, the loworder Proctor model was applied to describe the tip vortex velocity outside the viscous core, and the cavity size as a function of cavitation number. The flow field around the vortex cavity shows, in comparison with a flow field without cavitation, a region of retarded flow. This layer around the cavity interface is similar to the viscous core of a vortex without cavitation.

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Section: Introductionmentioning

confidence: 99%

Flow field measurement around vortex cavitation

2015

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“…This poses a serious threat to following aircraft, particularly when the following aircraft are small and must fly in close proximity to the airport runway during take-off and landing. This is a time when wake vortex circulation is at a peak level (Andrews, 1970;Arndt et. Al., 1991;McGowan, 1968).…”

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confidence: 99%

Wingtip Vortex Alleviation Using a Reverse Delta Type Add-on Device

Altaf¹

2017

IJAAA

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“…Tip-vortex cavitation can be viewed as a canonical problem that captures many of the essential physics associated with vortex cavitation in general [14]. In fact, much information can be obtained from water tunnel simulations of tip-vortex flow around stationary hydrofoils ( figure 3).…”

Section: Phenomenological Study Of Vortex Cavitationmentioning

confidence: 99%

“…Figure 5 shows the development of a cavitating vortex leaving the tip of a propeller blade, and being composed from a vortex sheet, rather than a single vortex (Figure 5b [14]. Shown on the right is a detailed view showing that cavitation first occurs at a distance of about x/c o ¼ 0.15 [15].…”

Section: Phenomenological Study Of Vortex Cavitationmentioning

confidence: 99%

The singing vortex

et al. 2015

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Marine propellers display several forms of cavitation. Of these, propeller-tip vortex cavitation is one of the important factors in propeller design. The dynamic behaviour of the tip vortex is responsible for hull vibration and noise. Thus, cavitation in the vortices trailing from tips of propeller blades has been studied extensively. Under certain circumstances cavitating vortices have been observed to have wave-like disturbances on the surfaces of vapour cores. Intense sound at discrete frequencies can result from a coupling between tip vortex disturbances and oscillating sheet cavitation on the surfaces of the propeller blades. This research article focuses on the dynamics of vortex cavitation and more in particular on the energy and frequency content of the radiated pressures.

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Some observations of tip-vortex cavitation

Cited by 161 publications

References 36 publications

Flow field measurement around vortex cavitation

Flow field measurement around vortex cavitation

Wingtip Vortex Alleviation Using a Reverse Delta Type Add-on Device

The singing vortex

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