Method of reducing frictional resistance of a hull, and frictional resistance reducing vessel

Abstract

In the present invention, perpendicular flows (Fa) along a running direction of a hull ( 10 ) are induced accompanying the operation of a vessel, and vortex structures in the vicinity of a submerged surface ( 11 ) of the hull are varied by the perpendicular flows. As a result, energy consumption during operation of the vessel can effectively be conserved by reducing the frictional resistance with a low level of energy consumption.

What is claimed is:  
     
         1 . A method of reducing frictional resistance of a hull comprising a step for inducing perpendicular flows along a running direction of the hull accompanying operation of a vessel, and a step for varying vortex structures in the vicinity of a submerged surface of the hull by the perpendicular flows.  
     
     
         2 . A method of reducing frictional resistance of a hull according to  claim 1 , wherein said perpendicular flows are induced by vortices which are generated by an object which is provided on said submerged surface.  
     
     
         3 . A method of reducing frictional resistance of a hull according to  claim 1 , wherein said vortex structures are varied by vortices which are generated by an object which is provided on said submerged surface.  
     
     
         4 . A frictional resistance reducing vessel for reducing frictional resistance between a submerged surface of a hull and water, comprising a vortex generator which generates vortices for inducing perpendicular flows along a running direction of the hull accompanying operation of the vessel.  
     
     
         5 . A method of reducing frictional resistance of a hull by releasing bubbles onto a submerged surface of the hull comprising: a step for forming a negative pressure region at a low pressure relative to a gaseous space in the water accompanying operation of a vessel, and inducing a gas being led from the gaseous space to the negative pressure region; and a step for inducing perpendicular flows along a running direction of the hull and varying vortex structures in the vicinity of the submerged surface by the perpendicular flows.  
     
     
         6 . A method of reducing frictional resistance of a hull according to  claim 5 , wherein said negative pressure region is developed by a cyclic flow which is generated by a wing which is provided on said submerged surface, and said perpendicular flows are generated by vortices which are generated by the cyclic flow.  
     
     
         7 . A method of reducing frictional resistance of a hull according to  claim 6 , wherein an upward lift which acts on the hull is generated by said wing.  
     
     
         8 . A frictional resistance reducing vessel for reducing frictional resistance between a submerged surface of a hull and water, comprising: a negative pressure forming portion which is provided on the submerged surface and which forms a negative pressure region at a low pressure relative to a gaseous space in the water; an outlet which is provided behind the negative pressure forming portion; a flow path of which one end opens to a gaseous space and the other end opens to the water via said outlet; and an object which generates vortices for inducing perpendicular flows along a running direction of the hull accompanying operation of the vessel.