Frictional resistance reducing vessel and a method of reducing frictional resistance of a hull

Abstract

The object of the present invention is to provide a frictional resistance reducing vessel and method of reducing the frictional resistance of a hull that are able to effectively conserve energy consumed during operation by reducing frictional resistance at a low level of energy consumption. In the present invention, a negative pressure region ( 51 ), which is at low pressure relative to a gaseous space, is formed in the water accompanying operation of a hull ( 30 ), and together with bubbles being guided to this negative pressure region ( 51 ) in the water from the gaseous space, the state of this negative pressure region ( 51 ) is changed based on changes in vessel velocity.

What is claimed is:  
     
         1 . A frictional resistance reducing vessel that reduces frictional resistance of a hull by releasing bubbles onto the submerged surface of a hull, provided with: 
 a negative pressure forming portion arranged protruding from said submerged surface that forms a negative pressure region in the water which is at low pressure relative to a gaseous space;    an air outlet for releasing bubbles towards said negative pressure region;    a flow path of which one end is open to a gaseous space and the other end is open into the water via said air outlet; and,    a drive mechanism that changes at least one of the protruding state of said negative pressure forming portion from said submerged surface, the opening surface area of said air outlet, and the flow path cross-sectional surface area of said flow path.    
     
     
         2 . The frictional resistance reducing vessel according to    claim 1    that is also provided with a control apparatus that controls said drive mechanism based on changes in vessel speed.  
     
     
         3 . A method of reducing frictional resistance of a hull by releasing bubbles onto the submerged surface of a hull; wherein, 
 a negative pressure region at a low pressure relative to a gaseous space is formed in the water accompanying vessel operation, and together with a gas being led from the gaseous space to the negative pressure region in the water, the state of said negative pressure region is changed based on changes in vessel speed.    
     
     
         4 . A frictional resistance reducing vessel that reduces the frictional resistance of a hull by releasing bubbles onto the submerged surface of a hull, provided with: 
 an outer cylindrical portion of which one end is open to the atmosphere and the other end is open in the water;    an inner cylindrical portion, which together with being installed in the state of being inserted into the outer cylindrical portion, one end is open to the atmosphere and the other end is open into the water; and,    an asymmetrical air blowing portion provided on the other end of said inner cylindrical portion protruding from said submerged surface, the protruding state of which is in the lengthwise direction of the hull.    
     
     
         5 . The frictional resistance reducing vessel according to    claim 4    that is also provided with a protrusion adjustment means for adjusting the protruding state of said air blowing portion.  
     
     
         6 . The frictional resistance reducing vessel according to either of claims  4  of  5  wherein, the cross-sectional shapes of said outer cylindrical portion and said inner cylindrical portion are isosceles triangles.  
     
     
         7 . A frictional resistance reducing vessel that reduces the frictional resistance of a hull by releasing bubbles onto the submerged surface of a hull, provided with: 
 a negative pressure forming portion arranged protruding from said submerged surface so that cavitation occurs in the water behind it due to the relative flow of water with respect to the hull during operation; a discharge outlet provided behind said negative pressure forming portion; and, a flow path of which one end is open to a gaseous space and the other end is open into the water via said discharge outlet.    
     
     
         8 . A frictional resistance reducing vessel that reduces the frictional resistance of a hull by releasing bubbles onto the submerged surface of a hull, provided with: 
 an indentation formed so as to be recessed from the submerged surface;    a negative pressure forming member, which together with being supported to as to rotate freely inside said indentation, forms a negative pressure region in the water at a low pressure relative to a gaseous space by having at least a portion protrude from said submerged surface;    a flow path for guiding air from the gaseous space to the negative pressure region in the water, one end of which being open to the gaseous space, and the other end being open into said indentation; and,    an angle adjusting mechanism for causing at least a portion of said negative pressure forming member to protrude in a prescribed state from said submerged surface that supports said negative pressure forming member and adjusts the angle of said negative pressure forming member.    
     
     
         9 . A frictional resistance reducing vessel that reduces the frictional resistance of a hull by releasing bubbles onto the submerged surface of a hull, provided with: 
 an indentation provided in said submerged surface;    a flow path of which one end is open to the atmosphere and the other end is open to the inside of said indentation;    a wing body having a wing that is arranged within said indentation; and,    a positioning mechanism that supports said wing body in a prescribed direction while allowing to move freely and positions said wing at a prescribed position;    said positioning mechanism positioning said wing so that the inside of said indentation is open relative to the flow of water and results in negative pressure relative to the atmosphere during reduction of frictional resistance.    
     
     
         10 . The frictional resistance reducing vessel according to    claim 9    wherein, said positioning mechanism positions said wing so that the lower surface of said wing is at roughly the same height as said submerged surface during times other than when reducing frictional resistance.  
     
     
         11 . The frictional resistance reducing vessel according to either of claims  9  or  10  wherein, said switching mechanism has an operational means that allows the position of said wing to be freely manipulated from the deck.