Tip-Vortex Induced Cavitation on a Ducted Propulsor

Chesnakas, Christopher J.; Jessup, Stuart D.

doi:10.1115/fedsm2003-45320

Cited by 13 publications

(21 citation statements)

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“…9 McCormick scaling has proven useful for scaling the formation of developed tip vortex cavitation, but it often fails to scale inception pressure when the cavitation events are very intermittent or when there are multiple interacting vortices present in the flow. 10 A recent study of vortex cavitation in the wake of a ducted propulsor showed that the location and inception pressure of the cavitation was associated with the presence of multiple, interacting vortices and not the primary vortex location of lowest pressure. [10][11][12] The complex, unsteady, and stochastic nature of these vortex-laden flows makes the study of vortex cavitation challenging.…”

Section: Introductionmentioning

confidence: 99%

“…10 A recent study of vortex cavitation in the wake of a ducted propulsor showed that the location and inception pressure of the cavitation was associated with the presence of multiple, interacting vortices and not the primary vortex location of lowest pressure. [10][11][12] The complex, unsteady, and stochastic nature of these vortex-laden flows makes the study of vortex cavitation challenging. Consequently, it is useful to examine vortex cavitation resulting from the simpler canonical interactions, such as those that occur between two initially parallel line vortices.…”

Section: Introductionmentioning

confidence: 99%

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Cavitation inception during the interaction of a pair of counter-rotating vortices

et al. 2012

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Pairs of unequal strength, counter-rotating vortices were produced to examine the inception and dynamics of vortex cavitation as the vortices undergo a longwavelength instability. The instability causes the weaker, secondary vortex to be turned and stretched by the stronger primary vortex. Folding and stretching of the secondary vortices result in sharp reductions of the core pressure. Here, these sharp and transient reductions in the secondary vortex core pressure produced incipient cavitation at static pressures that were as much as 20 times higher than that required for inception in the core of the unstretched secondary vortex. In addition, the majority of nuclei measured was of the order of 1 lm in size, which requires tension on the order of 100 kPa for cavitation inception to occur. The flow parameters that lead to the instability and cavitation inception in the secondary vortex are examined, and the measured event rates are correlated to freestream nuclei populations and static pressure. These measurements, combined with observations of the elongated bubbles themselves, suggest that stretching produced large tensions in the core of the secondary vortex due to both a reduction in the secondary vortex core size and the creation of a jetting flow in the vortex core.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cavitation inception during the interaction of a pair of counter-rotating vortices

et al. 2012

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“…The influence of Reynolds number among experiments is smaller than the general propellers and hydrofoils in open water. The measured dependence on inception number for the propulsor is 0.21 (Chesnakas & Jessup, 2003), which is significantly lower than the empirical values 0.3 (Farrell & Biller, 1994), or 0.4-0.5 (Arndt, 2002). The visual inception and the sub-visual cavitation events occur approximately at the merge location of tip-leakage vortex and trailing edge vortex.…”

Section: Numerical Results and Discussionmentioning

confidence: 61%

Numerical Simulations of Tip Leakage Vortex Cavitation Flows Around a NACA0009 Hydrofoil

Wang¹,

Liu²

2018

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

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Numerical simulations of full wet and cavitating tip leakage vortex flows are studied. By comparing vortex structures, strain rates and Reynolds shear stresses distributions in the vortex region for full wet flows between numerical and experimental results, it is found that the numerical results with the nonlinear k-turbulence model is in good agreement with the experimental results. Both full wet and cavitating flows around a NACA0009 blade with various gaps between the tip and end-wall are studied to investigate the influence of gap width on the development of tip vortex and tip vortex cavitation. Good agreements are obtained on the trajectories of tip leakage vortex by comparing the numerical results and experimental data. When the dimensionless gap size < 0.7, numerical results show that there is an apparent difference on the vertex trajectories behind the hydrofoil between full wet and cavitating flows.

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“…As expected, decreasing the gap size from 100% to zero increases the maximum circulation, and the circulation at the tip does not change much except for the case of zero gap. In the case that gap between tunnel wall and blade tip is small, the strong tip vortex which the viscous effect is dominant would develop from the leading edge of the blade and affects the performance of propeller [3,4]. In order to capture the viscous flow effect, the method of the orifice equation model which has been successfully applied to the panel method by [13] and [20] has to to be coupled with the present method.…”

Section: Numerical Resultsmentioning

confidence: 99%

A BEM for the modeling of unsteady propeller sheet cavitation inside of a cavitation tunnel

Lee

Kinnas

2005

Comput Mech

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A boundary element method is applied to predict the unsteady cavitating performance of marine propellers subject to a non-axisymmetric inflow with the complete tunnel wall effect. The tunnel and propeller problem is solved directly to predict the fully unsteady performance of the cavitating propeller. The cavitation on blade and wake surface is determined by applying the dynamic and the kinematic boundary conditions on the cavity surface. The potential on the cavity surface is known from the dynamic boundary condition and the relation between cavitation number and cavity velocity. Once the boundary value problem is solved for the unknowns-the potentials on the wetted blade surface and the normal derivative of potentials on the cavity surface -the new cavity shape is adjusted by using the normal derivative of the potential. The potential on the new cavity surface is determined by using the kinematic boundary condition on the cavity. The procedure is repeated until the cavity shape converges and the pressure on the cavity becomes constant. To validate the present method, the effects of the number of blade panels and the dimensions of the tunnel walls on blade forces are presented. The predicted cavity patterns are compared with those observed from experiment.

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Tip-Vortex Induced Cavitation on a Ducted Propulsor

Cited by 13 publications

References 0 publications

Cavitation inception during the interaction of a pair of counter-rotating vortices

Cavitation inception during the interaction of a pair of counter-rotating vortices

Numerical Simulations of Tip Leakage Vortex Cavitation Flows Around a NACA0009 Hydrofoil

A BEM for the modeling of unsteady propeller sheet cavitation inside of a cavitation tunnel

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