Hydrodynamics of a Displacement Air Cavity Ship

• To study the resistance reduction of an air cavity for adisplacement vessel, a simplified model of a single cavityis tested in a cavitation tunnel. The drag force actingon the cavity and the aft plate were measured andthe water-air interface was monitored in different conditions.Behavioural changes to the free surface wereobserved by changing the geometry and flow characteristicslike air pressure, air flow rate and water flow speed.Computational model for different cases with the samegeometry and conditions were simulated using computationalfluid dynamics(CFD).The length of the cavity was designed to include approximately2.5 times the expected wavelength of thewater-air interface with Froude number based on theship length of 0.19 which approximately represents adisplacement ship with multi-wave air cavity at its cruisingspeed.Parameters like cavity pressure play an important rolefor the wave’s shape and the stability of the free surfaceinside the cavity. Both computation and experimentshow that the amplitude of the wave is sensitive to the airpressure in the cavity and the re-attachment of the waterto the rear end of the cavity has a close correlationto the inlet air pressure and water velocity. The ultimategoal of this investigation is to minimize effective powerincluding air supply while reducing resistance in/aroundthe cavity, but equally important is it to gain amore basicunderstanding of the air-cavity’s behaviour and possibleadditional resistance components.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Strömningsmekanik och akustik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Fluid Mechanics and Acoustics (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Naturresursteknik -- Marin teknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Engineering -- Marine Engineering (hsv//eng)

Nyckelord

Displacement Hull

CFD

Air Lubrication

Air Cavity Ship

Hydrodynamics

Publikations- och innehållstyp

kon (ämneskategori)

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