Twenty-First Symposium on Naval Hydrodynamics (1997) / Chapter Skim
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Yaw Effects on Model-Scale Ship Flows
Yaw Effects on Model-Scale Ship Flows
Pages 312-327
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From page 312... ...
The data includes: photographs and video; resistance, side force, and yaw moment; linkage, Tim, and heel angle; wave profiles along the hull and wave elevations; and meanvelocity and pressure fields for numerous crossplanes from the bow to the near wake. Detailed descriptions are provided of the experimental equipment, procedures, and uncertainty analysis.
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From page 313... ...
Additionally, wave profiles along the hull and wave elevations are measured for a range of yaw angles and high (0.316)
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From page 314... ...
Forces, yaw moment. and displacements Resistance, sideforce, yaw moment, linkage, trim, and heel angle are measured for five yaw angles, p=0°, 2.5°, 5°, 7.5°, and 10° and a range of Fr, Fr=0.10.35 (Uo=0.55-1.91 m/s)
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From page 315... ...
After reaching a steady speed and allowing the wave field to reach steady state, the gauges are adjusted to rest on the free surface. In areas of high free-surface turbulence such as the near wake and at the crest of the port bow wave for Fr=0.316 and p=10°, the probes are adjusted to a level of average wave elevation 1 .
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From page 316... ...
At the FP of a wedge-shaped bow, a thin film develops aft of the free surface-bow stem juncture and transitions into a bow wave. The thin film can be a site where bow vortices are generated.
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From page 317... ...
There is very little free-surface turbulence in the wave pattern except along the hull-free surface contact line downstream of the bow wave and at the stern and wake where there is moderate unsteadiness. At ,B=5°, the wave field is altered.
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From page 318... ...
The heel angle is roughly linear in Fr for ,B=2.5° and then increasingly nonlinear in Fr for the higher yaw angles. Note that for p=10°, Pr=0.32 was the maximum Fr at which the breaking bow wave did not swamp the model Wave profiles Wave profiles on the hull are measured for high and low Fr and p=0°, 5~, and 10° and are shown in Figure 7.
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From page 319... ...
As per the wave profiles, the local regions are affected only for x<0.25, whereas in the global regions, the wave patterns are significantly changed with increasing ~ from bow to stern. Dense clustering of contours at the bow on the port side confirms the sharp increase of the bow wave at the FP and the existence of an attached thin film.
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From page 320... ...
The vorticity pattern appears to rotate counterclockwise and reorganizes its structure with increasing x, i.e., at x=1, the long axis is parallel with the stern stem and subsequently parallel with the free surface at x=1.2. The afterbody-keel vortex dissipates relatively fast with a trajectory as per the afterbody-bilge vortex but at an angle of about 2.6° to the centerplane.
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From page 321... ...
The data includes: photographs and video; resistance, side force, and yaw moment; linkage, trim, and heel angle; wave profiles along the hull and wave elevations; and meanvelocity and pressure fields for numerous crossplanes from the bow to the ne~ wake. Detailed descriptions are provided of the expenmental equipment, procedures, and uncertainty analysis.
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From page 322... ...
, "Meanflow measurements in the boundary layer and wake and wave field of a Series 60 CB=0.6 ship model-part O: scale effects on near-field wave patterns and comparisons with inviscid theory," J Ship Research, Vol.
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From page 323... ...
(a) Transverse and diverging waves of a full-scale ship Diverging waves__ it_ ~ ,.
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From page 324... ...
Photographs of the wave field at Fr=0.3i6 v =oo · =2.5° _ 3=5° · ~7.5° O =10° + 3=0°: Toda et al.
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From page 325... ...
.316 ~ 0.0 0.2 0.4 0.6 0.8 1.0 1.2 x 0.8 0.6 0.4 50.2~ ~_~ ~_ -0.4 0.0 0.2 0.4 0.6 0.8 1.0 1.2 x Figure 7. Wave profiles 0.4 0.3 0.2 0.1 y 0.0 -0.1 -0.2 -(~.3 t~ A ~ .
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From page 326... ...
~ _.\ I,._ alp"': ~ ~ :i 1 (b) total head W ~\~.~` .
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From page 327... ...
'at' \ '\ ~ \>,~ ~~ \~\~ ~~ : 'I'd ~ t0.25 ~\~% `-'.
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