Fluid Turbine Having Optimized Blade Pitch Profiles

Abstract

A fluid turbine comprising a rotor, having an axis of rotation, comprising at least two rotor blades disposed at a radius from the axis of rotation, each rotor blade having a pitch axis and a variable pitch angle. The fluid turbine comprises a mechanism operable to control the pitch angle of at least one rotor blade about its pitch axis and to vary the pitch angle of the rotor blade between various pitch angles as the blade moves radially about the axis of rotation of the rotor.

1 . A fluid turbine comprising:
 a rotor, having an axis of rotation, comprising at least two rotor blades disposed at a radius from the axis of rotation, traveling along a circumferential tangent path line, each rotor blade having a pitch axis and a variable pitch angle; and   a mechanism operable to control the pitch angle of at least one rotor blade about its pitch axis and to vary the pitch angle of the rotor blade from a first pitch angle at a first circumferential location about the axis of rotation to a second pitch angle at a second circumferential location about the axis of rotation, according to a non-sinusoidal pitch profile.   
     
     
         2 . The fluid turbine of  claim 1 , wherein the first rotor blade pitch angle is between 7 degrees and 15 degrees to a line tangent to the circumferential path of the rotor blade. 
     
     
         3 . The fluid turbine of  claim 1 , wherein the second rotor blade pitch angle is parallel to a line tangent to the circumferential path of the rotor blade. 
     
     
         4 . The fluid turbine of  claim 1 , wherein the second rotor blade pitch angle is between 20 degrees and 30 degrees to a plane orthogonal to a line tangent to the circumferential path of the rotor blade. 
     
     
         5 . The fluid turbine of  claim 1 , wherein the second rotor pitch angle is between 25 degrees and 35 degrees to a line tangent to the circumferential path of the rotor blade. 
     
     
         6 . The fluid turbine of  claim 1 , wherein the minimum rotor blade pitch angle for a rotor blade is imposed at a rotor position wherein that rotor blade is upstream of the axis of rotation of the rotor blade. 
     
     
         7 . The fluid turbine of  claim 1 , wherein the maximum rotor blade pitch angle for a rotor blade is imposed at a rotor position wherein that rotor blade is downstream of the axis of rotation of the rotor blade. 
     
     
         8 . A fluid turbine comprising:
 a rotor, having an axis of rotation, comprising at least two rotor blades disposed at a radius from the axis of rotation, traveling along a circumferential tangent path line, each rotor blade having a pitch axis and a variable pitch angle; and   a mechanism operable to control the pitch angle of at least one rotor blade about its pitch axis and to vary the pitch angle of the rotor blade from a first pitch angle at a first circumferential location about the axis of rotation to a second pitch angle at a second circumferential location about the axis of rotation to a third pitch angle at a third circumferential location about the axis of rotation, according to a non-sinusoidal pitch profile.   
     
     
         9 . The fluid turbine of  claim 8 , wherein the first rotor blade pitch angle is between 7 degrees and 15 degrees to a line tangent to the circumferential path of the rotor blade. 
     
     
         10 . The fluid turbine of  claim 8 , wherein the second rotor blade pitch angle is parallel to a line tangent to the circumferential path of the rotor blade. 
     
     
         11 . The fluid turbine of  claim 8 , wherein the second rotor blade pitch angle is between 20 degrees and 30 degrees to a line tangent to the circumferential path of the rotor blade. 
     
     
         12 . The fluid turbine of  claim 8 , wherein the second rotor pitch angle is between 25 degrees and 35 degrees to a line tangent to the circumferential path of the rotor blade. 
     
     
         13 . The fluid turbine of  claim 8 , wherein the minimum rotor blade pitch angle for a rotor blade is imposed at a rotor position wherein that rotor blade is upstream of the axis of rotation of the rotor blade. 
     
     
         14 . The fluid turbine of  claim 8 , wherein the maximum rotor blade pitch angle for a rotor blade is imposed at a rotor position wherein that rotor blade is downstream of the axis of rotation of the rotor blade. 
     
     
         15 . A fluid turbine comprising:
 a rotor, having an axis of rotation, comprising at least two rotor blades disposed at a radius from the axis of rotation, traveling along a circumferential tangent path line, each rotor blade having a pitch axis and a variable pitch angle; and   a mechanism operable to control the pitch angle of at least one rotor blade about its pitch axis and to vary the pitch angle of the rotor blade from a first pitch angle at a first circumferential location about the axis of rotation to a second pitch angle at a second circumferential location about the axis of rotation to a third pitch angle at a third circumferential location about the axis of rotation to a fourth pitch angle at a fourth circumferential location about the axis of rotation, according to a non-sinusoidal pitch profile.   
     
     
         16 . The fluid turbine of  claim 15 , wherein the second rotor blade pitch angle is parallel to a line tangent to the circumferential path of the rotor blade. 
     
     
         17 . The fluid turbine of  claim 15 , wherein the first rotor blade pitch angle is between 7 degrees and 15 degrees to a line tangent to the circumferential path of the rotor blade. 
     
     
         18 . The fluid turbine of  claim 15 , wherein the second rotor pitch angle is between 25 degrees and 35 degrees to a line tangent to the circumferential path of the rotor blade. 
     
     
         19 . The fluid turbine of  claim 15 , wherein the minimum rotor blade pitch angle for a rotor blade is imposed at a rotor position wherein that rotor blade is upstream of the axis of rotation of the rotor blade. 
     
     
         20 . The fluid turbine of  claim 15 , wherein the maximum rotor blade pitch angle for a rotor blade is imposed at a rotor position wherein that rotor blade is downstream of the axis of rotation of the rotor blade.