Improvement of Hydrofoil Performance by Partial Ventilated Cavitation in Steady Flow and Periodic Gusts

Kopriva, Jim; Arndt, Roger E. A.; Amromin, Eduard

doi:10.1115/1.2842147

Cited by 45 publications

(14 citation statements)

References 4 publications

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“…Amromin et al 2006, Kopriva et al (2007), and Kopriva et al (2008) discuss the use of partial cavitation to reduce the drag on a specially designed hydrofoil that has a contour designed to produce a leading-edge cavity that would smoothly reattach near the cavity mid-chord. Both natural and ventilated cavities were examined for a variety of foil shapes at chord-based Reynolds numbers of order 10 5 , with reported improvements in the foil lift-to-drag ratio of 30% to 50%.…”

Section: Ventilation Of Partial Cavities and Management Of The Cavitymentioning

confidence: 99%

Friction Drag Reduction of External Flows with Bubble and Gas Injection

Ceccio

2010

Annu. Rev. Fluid Mech.

467

248

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The lubrication of external liquid flow with a bubbly mixture or gas layer has been the goal of engineers for many years, and this article presents the underlying principles and recent advances of this technology. It reviews the use of partial and supercavities for drag reduction of axisymmetric objects moving within a liquid. Partial cavity flows can also be used to reduce the friction drag on the nominally two-dimensional portions of a horizontal surface, and the basic flow features of two-dimensional cavities are presented. Injection of gas can lead to the creation of a bubbly mixture near the flow surface that can significantly modify the flow within the turbulent boundary layer, and there have been significant advances in the understanding of the underlying physical process of drag reduction. Moreover, with sufficient gas flux, the bubbles flowing beneath a solid surface can coalesce to form a thin drag-reducing air layer. The current applications of these techniques to underwater vehicles and surface ships are discussed.

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Section: Ventilation Of Partial Cavities and Management Of The Cavitymentioning

confidence: 99%

Friction Drag Reduction of External Flows with Bubble and Gas Injection

Ceccio

2010

Annu. Rev. Fluid Mech.

467

248

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show abstract

“…2018, 8, flow velocity that is generated is up to 20.4 m/s [48]. The hydrofoil was used as the gust generator [1]. The gust generated by the twin hydrofoils is convected downstream at the mean flow velocity, oscillating at the prescribed frequencies.…”

Section: Bilinear Interpolationmentioning

confidence: 99%

“…Therefore, it is important to experimentally and numerically predict the cavitation shape. Kopriva et al [1], Lee et al [2,3], and Karn et al [4] experimentally investigated the changes in the cavitation shape due to inflow gust. The experiments were conducted in cavitation tunnels.…”

Section: Introductionmentioning

confidence: 99%

Development of Efficient and Accurate Parallel Computation Algorithm Using Moving Overset Grids on Background Multi-Domains for Complex Two-Phase Flows

Cheong

Seol³

et al. 2018

Applied Sciences

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The goal of this study involves developing an efficient and accurate parallel computation method for two-phase flow problems including complex moving foreign bodies. The proposed parallel computing techniques are based on the moving body-fitted grids’ overset on background multidomains with grid-overlapping at their interface. First, the cavitation flow over the hemispherical head form is investigated using the two-phase flow solver, which is validated by comparing the numerical and experimental results. Subsequently, the parallel computing technique based on the multidomain method that divides the computational domain into several smaller subdomains is proposed to facilitate more efficient numerical simulations. At the interface of the subdomains, the grid-overlapping method is proposed for more accurate simulations. The illustrative computations indicate that the accuracy of the parallel computation combined with the grid-overlapping method on multidomains is identical to that of the serial computation based on a single block, albeit with a significant reduction in the computation time. Finally, the moving overset grid technique is combined with the background multidomain method and applied to simulate the gust flow that is generated by the pitching motions of the twin hydrofoils. The overset grid technique includes the following three sequential steps: hole-cutting, finding donor cells, and bilinear interpolation. The prediction results for the inflow gust generated by oscillating hydrofoils closely follow the measured results.

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“…To utilize this promising technique on energy savings for ship operations, extensive work has been done on PCDR, mainly focusing on the cavitator design and establishing a relationship between relevant flow conditions and ventilation cost. For instance, Amromin et al (2006) and Kopriva et al (2008) measured the lift and drag coefficients on a hydrofoil cavitator to validate the effectiveness of cavitation theory for drag reduction schemes. Makiharju et al (2010) also used imaging techniques on cavity closure to determine the cavity shape, growth rate and collapse rate, closure oscillation, and closure type and observed the effect of each flow condition on the ventilation cost.…”

Section: Introductionmentioning

confidence: 99%

Internal flows of ventilated partial cavitation

et al. 2020

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Our study provides the first experimental investigation of the internal flows of ventilated partial cavitation (VPC) formed by air injection behind a backward-facing step. The experiments are conducted using flow visualization and planar particle image velocimetry (PIV) with fog particles for two different cavity regimes of VPC, i.e., open cavity (OC) and twobranch cavity (TBC), under various range of free stream velocity (U ) and ventilation rates (Q). Our experiments reveal similar flow patterns for both OC and TBC, including forward flow region near the air-water interface, reverse flow region, near-cavitator vortex, and internal flow circulation vortex. However, OC internal flow exhibits highly unsteady internal flow features, while TBC internal flow shows laminar-like flow patterns with a Kelvin-Helmholtz instability developed at the interface between forward and reverse flow regions within the cavity. Internal flow patterns and the unsteadiness of OC resemble those of turbulent flow separation past a backward-facing step (BF S flow), suggesting a strong coupling of internal flow and turbulent external recirculation region for OC. Likewise, internal flow patterns of TBC resemble those of laminar BF S flow, with the presence of unsteadiness due to the strong velocity gradient across the forward-reverse flow interface. The variation of the internal flow upon changing U or Q are further employed to explain the cavity regime transition and the corresponding change of cavity geometry. Our study suggests that the ventilation control can potentially stabilize the cavity in the TBC regime by delaying its internal flow regime transition from laminar-like to highly unsteady.

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Improvement of Hydrofoil Performance by Partial Ventilated Cavitation in Steady Flow and Periodic Gusts

Cited by 45 publications

References 4 publications

Friction Drag Reduction of External Flows with Bubble and Gas Injection

Friction Drag Reduction of External Flows with Bubble and Gas Injection

Development of Efficient and Accurate Parallel Computation Algorithm Using Moving Overset Grids on Background Multi-Domains for Complex Two-Phase Flows

Internal flows of ventilated partial cavitation

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