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Friday, July 31, 2020 | History

2 edition of Tip vortex cavitation characteristics and delay of inception on a three-dimensional hydrofoil found in the catalog.

Tip vortex cavitation characteristics and delay of inception on a three-dimensional hydrofoil

by William G. Souders

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Published by David W. Taylor Naval Ship Research and Development Center in Bethesda, Md .
Written in English


Edition Notes

Statementby William G. Souders, Gregory P. Platzer
SeriesShip Performance Department research and development report, DTNSRDC-81/007
ContributionsPlatzer, Gregory P., David W. Taylor Naval Ship Research and Development Center
The Physical Object
Paginationviii, 59 p. :
Number of Pages59
ID Numbers
Open LibraryOL24363781M
OCLC/WorldCa10587586

A three-dimensional, time-accurate, compressible, homogeneous multiphase Navier-Stokes method is applied to modeling developed cavitation flow over a hydrofoil at angle-of-attack. The configuration and cavitation numbers considered give rise . The workhorse for cavitation tests at HSVA is the large Hydrodynamics and Cavitation Tunnel HYKAT, allowing installation of complete ship models with rudder(s) and all other appendages in its huge test section. This way the realistic three-dimensional propeller inflow is generated by the ship model itself.

investigating unsteady maneuvering characteristics, the static pitch bias, θbias, is typically non-zero. For the tests described herein, the pitch bias is set to zero. The phase angle is set toπ/2, as recommended by [21]. In three-dimensional kinematics, the angle of attack profile varies along the span of the foil as it rolls and pitches. geo_carts geo_data scatter_charts scatter_data use_charts use_data growth count count

full text of "cavitation inception and internal flows with cavitation" see other formats ptnskdc, 7f -o// david w. taylor naval ship research and development center bethesda, maryland cavitation inception and internal flows with cavitation the fourth david w. taylor lecture • i \ by allan j. acosta california institute of technology approved for public release: distribution unlimited. on the characteristics of hydroentangling water jets. The results agreed with others’ experimental and computational results. Tao [12] studied the vortical structures of non-circular nozzles and swirl nozzles and their influence on cavitation inception control.


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Tip vortex cavitation characteristics and delay of inception on a three-dimensional hydrofoil by William G. Souders Download PDF EPUB FB2

Title. Tip vortex cavitation characteristics and delay of inception on a three-dimensional hydrofoil / Related Titles. Series: DTNSRDC/ Series: Ship Performance Department research and development report By.

Souders, William G. full text of "tip vortex cavitation characteristics and delay of inception on a three-dimensional hydrofoil" see other formats 0\n^kol. -ov/lxj / david w. taylor naval ship research and development center bethesda, maryland tip vortex cavitation characteristics and delay of inception on a three- dimensional hydrofoil by william g.

souders gregory p. platzer approved for public. Abstract. Cavitation is normally defined as the formation of the vapor phase in a liquid. The term cavitation (originally coined by R.E. Froude) can imply anything from the initial formation of bubbles (inception) to large-scale, attached cavities (supercavitation).

The tip vortex cavitation inception index, Ï{sub i}, of this hydrofoil geometry is about a factor of 2 lower than that of a conventional rounded hydrofoil tip. This inception improvement comes. Inception and desinence thresholds of tip vortex cavitation (TVC), generated by an elliptical NACA hydrofoil, are measured at different flow conditions for various gas contents.

Tip Vortex Formation and Cavitation B. Maines, B. Maines. Over the Reynolds number range tested, tip vortex cavitation inception has been observed to follow an almost universal scaling. and Souders, W. G.,“Tip Vortex Cavitation Characteristics and Delay on a Three-dimensional Hydrofoil,” 19th American Towing Tank Cited by: Experiments with polymers have also shown that the polymers cause the cavitation to become more violent.

To better understand the role of polymer in the delay of tip vortex cavitation, a theoretical analysis of tip vortex cavitation inception in pure water and in Cited by: 9. On the basis of these studies, a predict- tion model of inception of tip vortex cavitation is established[9] 2= mi LKC Reï ³ (1) where iï ³ is tip vortex cavitation inception number, K is an empirical coefficient, LC is lift coefficient, Re is Reynolds number and = by: 1.

A concept of tip vortex cavitation on propellers is described qualitatively, leading to the distinction of trailing vortices, local tip vortices and leading edge vortices. Improvements of the inception behaviour using this distinction are presented. Observations on developed tip.

Experiments were conducted on a large hydrofoil, of elliptical planform and NACA cross section, to test the influence of the water quality on: the cavitation map, the diameter of the cavity within the tip vortex and the noise measurements.

cavitation inception was first observed in the tip vortex about three chords downstream from the trailing edge and occured at a cavitation inception number, a, of about This cavitation then moved upstream as the tunnel pressure was decreased until it attached to the foil tip on the suction side near the trailing edge.

In the current study, our model is applied to predict tip vortex cavitation inception for a canonical problem in which the tip vortex flow is generated by a finite-span elliptic hydrofoil. The flow field is first obtained by a steady-state Navier-Stokes computation and provides the velocity and pressure fields for the spherical model.

The tip vortex cavitation is produced by low pressure in a tip vortex field, and it is the first type of cavitation to appear with intense noise. Therefore, to design the low noise propeller and hydrofoil, it is necessary to understand the generation mechanism, behavior and noise of Cited by: The generation of tip vortex cavitation (TVC) is a common phenomenon in marine propellers.

Therefore, it is important to find a way for the effective suppression of TVC. Based on the enlightenment of bionics, a propeller with winglets was numerically investigated by using a large eddy simulation (LES) model and the commercial software STAR-CCM+.

Various variables, Cited by: 2. formation mechanism. The tip vortex cavitation is produced by low pressure in a tip vortex field, and it is the first type of cavitation to appear with intense noise.

Therefore, to design the low noise pro-peller and hydrofoil, it is necessary to understand the generation mechanism, behavior and noise of tip vortex cavitation. Motivated by the problem of cavitation erosion, the position and strength of the roll-up vortex on the suction side of a Kaplan-type turbine blade with various endings is investigated.

Measurements are made on different models with simplified two-dimensional geometries using mainly particle image velocimetry. It is found that the greatest danger of Cited by: The inception of vortex cavitation at an early design stage is still difficult to forecast. The most reliable prediction of the full scale performance is achieved by means of model tests, which are possible for few designs only.

A simplified model to calculate the inception of tip vortex cavitation is developed and tested. Tip vortex cavitation characteristics and delay of inception on a three-dimensional hydrofoil / View Metadata By: Souders, William G.

- Platzer, Gregory P. - David W. Taylor Naval Ship Research and Development Center. kinds of tip-modified propellers have been introduced to reduce energy loss from tip vortices (Andersen et al. The blade geometry is more complicated due to tip bending and the variation of sheet cavitation and tip vortex cavitation is.

The test object is a three-dimensional hydrofoil, previously used by Dang [6], with a chord length of C = mm, a span of S = mm (spanning the entire test section), and a span wise varying angle of attack (3).

This geometric angle of attack varies as sketched in 4, rotating the sectional profile (NACA) around the mid chord position.

Approximate analysis of hydrofoil material impact on cavitation inception-3 The lift pulsation of the softer aluminum hydrofoil is clearly higher than these pulsations of the steel hydrofoil at the resonances, whereas the situation at other frequencies is invisible in the scale of Fig The 2D chordwise bending deformation can be.tain good force characteristics in the super cavitating-flow regime.

Under natural cavitating conditions, the degree of cavitation will be primarily in­ fluenced by the ambient pressure as.

related to the submergence of the foil and by the velocity of the craft. The force characteristics for the profile vary with the cavitation number.T1 - Numerical investigation of three-dimensional cavitation evolution and excited pressure fluctuations around a twisted hydrofoil. AU - Ji, Bin.

AU - Luo, Xianwu. AU - Wu, Yulin. AU - Miyagawa, Kazuyoshi. PY - /7. Y1 - /7Cited by: