Twenty-Third Symposium on Naval Hydrodynamics (2001) / Chapter Skim
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Experimental and Numerical Investigation of the Flow Around the Appendices of a Whitbread 60 Sailing Yacht
Experimental and Numerical Investigation of the Flow Around the Appendices of a Whitbread 60 Sailing Yacht
Pages 485-492
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From page 485... ...
. The study combines experiments on a scaled model in a wind tunnel and numerical simulations using the commercial code FLUENT.
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From page 486... ...
Close to the tip of the bulb, painting is accumulating, meaning that the "existing" bulb has not an optimal aerodynamic shape. SIDE VIEW TOP VIEW Figure 5 - comparison of the two bulbs Figure 7 - Oil visualization on the "existing" bulb A vortex tube attached at the tip of the bulb has also been observed when the keel is in incidence.
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From page 487... ...
is to illuminate particles injected in the flow by a Laser sheet and to observe the scattered light. In order to perform velocity measurements, two Laser pulses, separated by a short and know time interval At, are emitted to provide two images recorded on the same photographic plate or by a CCD camera providing the image in a numerical form.
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From page 488... ...
s ~~ angle of attack- ° Figure 14 -Drag value as function of attack Figure 12 - Schemativ view of the balance ·~ ~ Figure 13 - picture of the experimental set-up (balance + model) Lift value as function of angle of attack , angle of attack - ° Figure 15 - Lift value as function of angle of attack Lift curves are represented in Figure 15.
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From page 489... ...
. configuration DRAG T - negative T - negative T - positive T - positive Z Z New bulb New bulb Angle of attack O 6 O 6 O 6 O 6 O Balance N 0.54 0.436 0.636 0.466 0.551 0.462 0.49 0.414 Wake survey analysis N 0.543 0.444 0.63 0.456 0.543 0.438 0.506 0.398 Table 2 - comparison of drag values for two angle of attack NUMERICAL SIMULATION Description of the simulations The numerical simulations are performed using the commercial code FLUENT™ 5.2, which solves the Reynolds Averaged Navier-Stokes equations using a finite volume technique.
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From page 490... ...
The relative variation of the drag agrees well with the experimental observations, but only the k-£ turbulence model gives quantitative data close to the experimental values (within 2 %. Configuration T-negative T-positive z Numerical Simulation k-£ std.
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From page 491... ...
CONCLUSIONS Figure 23 - contours of skin friction Results of a detailed experimental investigation of the aerodynamic performances of two bulbs of different geometry have been presented. Experimental results include visualization of separation zone, the determination of vortex shedding frequencies and the measurement of values of drag and lift for different angles of attack.
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From page 492... ...
Lourenio: 'Particulate imcge ad tmcking velocimeby', von Kum m Institue L ctme Series, cou se note 148,1999 C.A. Marehaj: 'Aero-hyd odynamics of sciling', AdkrdColesNcutical,1991 FLUENT 5 User's Guide: Flu nt is c regi tered trad mark of Flu nt Inco porcted GAMBIT User's Guide: Gcmbit is c ~egistered trad mark of Flu nt Inco porcted
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