Vertical axis wind turbine with self-starting capabilities

Abstract

A vertical axis wind turbine and vertical axis wind turbine assembly comprising a rotary body and a plurality of blades. A cross section through each blade of the plurality of blades transverse to the rotary axis comprises an inner camber line, an outer camber line, and a chord line. The outer camber line comprises a first portion, a transition portion and a second portion. The second portion is longer, in the lengthwise direction, than a combined length of the first portion and the transition portion. The average second portion thickness is less than half an average first portion thickness. A magnitude of an average rate of change in a transition portion thickness is at least twice a magnitude of an average rate of change in a first portion thickness, and a magnitude of an average rate of change in a second portion thickness.

1 . A vertical axis wind turbine comprising:
 a rotary body operable to rotate about a rotary axis; and   a plurality of blades coupled to the rotary body to rotate the rotary body about the rotary axis, each blade of the plurality of blades comprising a leading edge and a trailing edge, wherein a cross section through each blade of the plurality of blades transverse to the rotary axis comprises
 an inner camber line facing the rotary body; 
 an outer camber line facing away from the rotary body; 
 a first convergence of the inner camber line and the outer camber line located at a first longitudinal extremity of the cross section where the leading edge intersects the cross section; 
 a second convergence of the inner camber line and the outer camber line located at a second longitudinal extremity of the cross section where the trailing edge intersects the cross section, that second longitudinal extremity being longitudinally opposed to the first longitudinal extremity; 
 a chord line extending directly from the first convergence to the second convergence in a lengthwise direction; and, 
 a widthwise axis substantially orthogonal to the lengthwise direction and extending, in a widthwise direction, from the inner camber line at an inner intermediate point to the outer camber line at an outer intermediate point; 
   wherein
 i) the inner camber line defines an inner camber path direction from the first convergence to the second convergence, and the outer camber line defines an outer camber path direction from the first convergence to the second convergence; 
 ii) at any point along the outer camber line the outer camber path direction is tangential to the outer camber line and comprises a first component extending in the lengthwise direction and a second component extending in the widthwise direction; 
 iii) at any point along the inner camber line, the inner camber path direction is tangential to the inner camber line and comprises a first component extending in the lengthwise direction and a second component extending in the widthwise direction; 
 iv) at any point along the outer camber line the first component of the outer camber path direction is positive; 
 v) the outer camber line comprises a first portion extending from the first convergence to the outer intermediate point, a transition portion extending from the outer intermediate point to a transition point and a second portion extending from the transition point to the second convergence; 
 vi) the second portion is longer, in the lengthwise direction, than a combined length of the first portion and the transition portion in the lengthwise direction; 
 vii) an average second portion thickness is less than half an average first portion thickness, the average first portion thickness, the average second portion thickness and an average transition portion thickness being measured from the outer camber line to the inner camber line in the widthwise direction; and, 
 viii) a magnitude of an average rate of change in a transition portion thickness is at least twice a magnitude of an average rate of change in a first portion thickness, and a magnitude of an average rate of change in a second portion thickness. 
   
     
     
         2 . The vertical axis wind turbine of  claim 1 , wherein the transition portion of the outer camber line intersects the chord line. 
     
     
         3 . The vertical axis wind turbine of  claim 1 , wherein a transition portion thickness at the outer intermediate point is greater than a thickness of any of the first portion, second portion, and transition portion, at any point other than the outer intermediate point along the outer camber line. 
     
     
         4 . The vertical axis wind turbine of  claim 1 , wherein a transition portion thickness at the outer intermediate point is more than twice a transition portion thickness at the transition point. 
     
     
         5 . The vertical axis wind turbine of  claim 1 , wherein the first portion is longer in the lengthwise direction than a length of the transition portion in the lengthwise direction. 
     
     
         6 . The vertical axis wind turbine of  claim 1 , wherein a length of the second portion in the lengthwise direction is more than thrice the length of the transition portion in the lengthwise direction. 
     
     
         7 . The vertical axis wind turbine of  claim 1 , wherein an overall length of the blade is more than four times a length of the transition portion in the lengthwise direction, the overall length of the blade being measured between the first convergence and the second convergence of the inner camber line and the outer camber line in the lengthwise direction. 
     
     
         8 . The vertical axis wind turbine of  claim 1 , wherein an overall length of the blade, in the lengthwise direction, is more than five times a transition portion thickness at the outer intermediate point. 
     
     
         9 . The vertical axis wind turbine of  claim 1 , wherein each blade of the plurality of blades comprises a foam core with a carbon reinforced ribbing and spar, that core being covered with carbon fiber. 
     
     
         10 . The vertical axis wind turbine of  claim 1 , further comprising a generator in mechanical communication with the rotary body. 
     
     
         11 . An assembly for converting kinetic energy from the wind into mechanical energy comprising:
 a rotary body operable to rotate about a rotary axis; and   a plurality of blades couplable to the rotary body to rotate the rotary body about the rotary axis, wherein each blade of the plurality of blades comprises a leading edge and a trailing edge, wherein a cross section through each blade of the plurality of blades transverse to the rotary axis comprises
 an inner camber line; 
 an outer camber line; 
 a first convergence of the inner camber line and the outer camber line located at a first longitudinal extremity of the cross section where the leading edge intersects the cross section; 
 a second convergence of the inner camber line and the outer camber line located at a second longitudinal extremity of the cross section where the trailing edge intersects the cross section, that second longitudinal extremity being longitudinally opposed to the first longitudinal extremity; 
 a chord line extending directly from the first convergence to the second convergence in a lengthwise direction; and 
 a widthwise axis substantially orthogonal to the lengthwise direction and extending, in a widthwise direction, from the inner camber line at an inner intermediate point to the outer camber line at an outer intermediate point; 
   wherein
 i) each blade of the plurality of blades comprises couplers for coupling the blade to the rotary body such that the inner camber line faces the rotary body, and the outer camber line faces away from the rotary body; 
 ii) the inner camber line defines an inner camber path direction from the first convergence to the second convergence, and the outer camber line defines an outer camber path direction from the first convergence to the second convergence; 
 iii) at any point along the outer camber line the outer camber path direction is tangential to the outer camber line and comprises a first component extending in the lengthwise direction and a second component extending in the widthwise direction; 
 iv) at any point along the inner camber line, the inner camber path direction is tangential to the inner camber line and comprises a first component extending in the lengthwise direction and a second component extending in the widthwise direction; 
 v) at any point along the outer camber line the first component of the outer camber path direction is positive; 
 vi) the outer camber line comprises a first portion extending from the first convergence to the outer intermediate point, a transition portion extending from the outer intermediate point to a transition point and a second portion extending from the transition point to the second convergence; 
 vii) the second portion is longer, in the lengthwise direction, than a combined length of the first portion and the transition portion; 
 viii) an average second portion thickness is less than half an average first portion thickness, the average first portion thickness, the average second portion thickness and an average transition portion thickness being measured from the outer camber line to the inner camber line in the widthwise direction; and, 
 ix) a magnitude of an average rate of change in a transition portion thickness is at least twice a magnitude of an average rate of change in a first portion thickness, and a magnitude of an average rate of change in a second portion thickness. 
   
     
     
         12 . The assembly of  claim 11 , wherein the couplers impede coupling of each blade of the plurality of blades to the rotary body such that the outer camber line faces the rotary body, and the inner camber line faces away from the rotary body. 
     
     
         13 . The assembly of  claim 11 , wherein the transition portion of the outer camber line intersects the chord line. 
     
     
         14 . The assembly of  claim 11 , wherein a transition portion thickness at the outer intermediate point is greater than a thickness of any of the first portion, second portion, and transition portion, at any point other than the outer intermediate point along the outer camber line. 
     
     
         15 . The assembly of  claim 11 , wherein a transition portion thickness at the outer intermediate point is more than twice a transition portion thickness at the transition point. 
     
     
         16 . The assembly of  claim 11 , wherein the first portion is longer in the lengthwise direction than a length of the transition portion in the lengthwise direction. 
     
     
         17 . The assembly of  claim 11 , wherein a length of the second portion in the lengthwise direction is more than thrice the length of the transition portion in the lengthwise direction. 
     
     
         18 . The assembly of  claim 11 , wherein an overall length of the blade is more than four times a length of the transition portion in the lengthwise direction, the overall length of the blade being measured between the first convergence and the second convergence of the inner camber line and the outer camber line in the lengthwise direction. 
     
     
         19 . The assembly of  claim 11 , further comprising a generator adapted for mechanical communication with the rotary body. 
     
     
         20 . A vertical axis wind turbine comprising:
 a rotary body operable to rotate about a rotary axis; and   a plurality of blades coupled to the rotary body to rotate the rotary body, wherein each blade of the plurality of blades comprises an airfoil-shaped body having a substantially symmetrical portion, and an asymmetrical portion having a outer camber bordering a cut-away portion, and wherein a cross-section through each blade of the plurality of blades transverse to the rotary axis comprises a first endpoint located at a first longitudinal extremity of the cross-section, a second endpoint located at a second longitudinal extremity of the cross-section, a chord line extending from the first longitudinal extremity to the second longitudinal extremity, a widthwise direction substantially perpendicular to the chord line, an inner camber line, an outer camber line, a cut-away length, and a cut-away depth,   wherein
 i) throughout the substantially symmetrical portion of the cross-section of each blade, an average magnitude of a widthwise distance between the outer camber line and the chord line is between 90 percent and 110 percent of an average magnitude of a widthwise distance between the inner camber line and the chord line; 
 ii) a length of the substantially symmetrical portion comprises more than one tenth of the length of the chord line, the length of the substantially symmetrical portion being measured parallel to the chord line; 
 iii) the outer camber surface of each blade of the plurality of blades faces away from the rotary body; 
 iv) throughout the asymmetrical portion of the cross-section of each blade, an average of a first displacement from the chord line to the inner camber line is more than three times an average of a second displacement from the chord line to the outer camber line, the first displacement being positive toward the rotary axis, and the second displacement being positive away from the rotary axis; 
 v) at any point along the chord line, there is one and only one corresponding point along the inner camber line in the widthwise direction, and one and only one corresponding point along the outer camber line in the widthwise direction; 
 vi) the cut-away length comprises more than seventy percent of the overall length of the cross section; and 
 vii) the cut-away depth comprises more than sixty percent of the maximum thickness of the airfoil-shaped body and less than eighty percent of the maximum thickness of the airfoil-shaped body.