Turbine with unevenly loaded rotor blades

Abstract

An unevenly loaded turbine rotor blade is disclosed herein, the blade including a power-extracting region adapted for radially-varied (relative to the axis of rotation) power extraction per mass flow rate. The pitch and/or shape of the airfoil at a first radial position may be configured, so that power extraction per mass flow rate at the first radial position is different than power extraction per mass flow rate at a second radial position. Thus, the power-extracting region may be advantageously configured to take advantage of a non-uniform flow profile across a rotor plane such as may be induced using a shrouded turbine.

1 . A shrouded axial flow fluid turbine comprising:
 an aerodynamically contoured turbine shroud having an inlet and configured to produce a non-uniform fluid velocity profile across a rotor plane when exposed to a fluid flow; and   a rotor disposed downstream of the inlet and configured to extract energy from fluid passing through the rotor plane, the rotor comprising:
 a central hub; and 
 a plurality of blades, each blade including:
 a root region having a blade root; 
 a tip region having a blade tip; 
 a mid-region disposed between the root region and the tip region; and 
 a blade axis extending radially from the blade root to the blade tip; each blade configured to have a value of power extraction per mass flow rate at a radial position along the blade axis that is greater at a first radius in the tip region of the blade than at second radius in the mid-region of the blade when exposed to the non-uniform fluid velocity profile. 
 
   
     
     
         2 . The shrouded axial flow fluid turbine of  claim 1 , wherein an average value of power extraction per mass flow rate for radial positions along the blade axis in the tip region is larger than an average value of power extraction per mass flow rate for radial positions along the blade axis in the mid-region when exposed to the non-uniform fluid velocity profile. 
     
     
         3 . The shrouded axial flow fluid turbine of  claim 1 , wherein an average value of power extraction per mass flow rate for radial positions along the blade axis in the mid-region is larger than an average value of power extraction per mass flow rate for radial positions along the blade axis in the root region when exposed to the non-uniform fluid velocity profile. 
     
     
         4 . The shrouded axial flow fluid turbine of  claim 1 , wherein each blade is configured to have a value of power extraction per mass flow rate at a radial position along the blade axis that varies as a function of distance of the radial position from a central axis of rotation of the rotor when exposed to the non-uniform fluid velocity profile. 
     
     
         5 . The shrouded axial flow fluid turbine of  claim 1 , wherein a pitch, a chord length and a camber of each blade at each radial position along the blade axis are configured to produce a non-uniform power extraction per mass flow rate profile along the blade axis. 
     
     
         6 . The shrouded axial flow fluid turbine of  claim 1 , wherein, for each blade, an average value of power extraction per mass flow rate for radial positions along the blade axis in the tip region is between 20% and 45% greater than an average value of power extraction per mass flow rate for radial positions along the blade axis from the blade root to the blade tip. 
     
     
         7 . The shrouded axial flow fluid turbine of  claim 1 , wherein, for each blade, an average value of power extraction per mass flow rate for radial positions along the blade axis in the root region is between 20% and 45% less than an average value of power extraction per mass flow rate for radial positions along the blade axis from the blade root to the blade tip. 
     
     
         8 . The shrouded axial flow fluid turbine of  claim 1 , wherein the turbine shroud further comprises one or more mixing devices disposed downstream of the rotor and extending downstream. 
     
     
         9 . The axial flow fluid turbine of  claim 10 , wherein the one or more mixing devices comprise mixer lobes. 
     
     
         10 . The axial flow fluid turbine of  claim 10 , further comprising an ejector shroud downstream of the turbine shroud. 
     
     
         11 . The axial flow fluid turbine of  claim 12 , wherein turbine shroud with one or more mixing devices and the ejector shroud form a mixer-ejector pump, and the wherein the non-uniform flow velocity profile at the rotor plane is created, in part, by the mixer-ejector pump. 
     
     
         12 . The axial flow fluid turbine of  claim 10 , wherein the mixing devices function as flow straighteners to straighten a fluid flow downstream of the rotor. 
     
     
         13 . A rotor blade coupleable to a rotor of a shrouded fluid turbine having a turbine shroud that produces a non-uniform fluid velocity profile across a rotor plane when exposed to a fluid flow, the rotor including a central hub configured to receive one or more rotor blades, the rotor blade comprising:
 a root region having a blade root;   a tip region having a blade tip;   a mid-region disposed between the root region and the tip region; and   a blade axis extending from the blade root to the blade tip;   wherein the blade is configured to, when connected with the central hub, have a value of power extraction per mass flow rate at a radial position along the blade axis that is greater at a first radius in the tip region of the blade than at a second radius in the mid-region of the blade when exposed to the non-uniform fluid velocity profile.   
     
     
         14 . The rotor blade of  claim 13 , wherein a pitch of the blade as a function of radial position along the blade axis is configured to, when connected with the central hub, produces an average value of power extraction per mass flow rate for radial positions along the blade axis in the tip region greater than an average value of power extraction per mass flow rate for radial positions along the blade axis in the mid-region when exposed to the non-uniform fluid velocity profile. 
     
     
         15 . The rotor blade of  claim 13 , wherein a pitch of the blade as a function of radial position along the blade axis is configured to, when connected with the central hub, produce a negative average value of power extraction per mass flow rate or radial positions along the blade axis in the root region when exposed to the non-uniform fluid velocity profile. 
     
     
         16 . A rotor configured for use with a shrouded fluid turbine having a turbine shroud that creates a non-uniform fluid velocity profile across a rotor plane when exposed to a fluid flow, the rotor comprising:
 a central hub with a central axis of rotation;   one or more rotor blades, each of the one or more rotor blades comprising:
 a root region having a blade root that couples with the central hub; 
 a tip region having a blade tip; 
 a mid-region disposed between the root region and the tip region; and 
 a blade axis extending from the blade root to the blade tip; 
   
       wherein, for each of the one or more rotor blades, a pitch of the blade as a function of radial position along the blade axis is configured to, when connected with the central hub, produce a power extraction per mass flow rate that is greater at a first radius in the tip region of the blade than at second radius in the mid-region of the blade when exposed to the non-uniform fluid velocity profile. 
     
     
         17 . A method of operating a shrouded axial flow fluid turbine including an aerodynamically contoured turbine shroud having an inlet, and a rotor disposed downstream of the turbine shroud inlet, the rotor including a plurality of blades, each blade having a root region including a blade root, a tip region including a blade tip, and a mid-region disposed between the root region and the tip region, the method comprising:
 establishing a non-uniform fluid flow through a rotor plane in which an average velocity of fluid flowing through an area of the rotor plane associated with the tip region of each blade is greater than an average velocity of fluid flowing through an area of the rotor plane associated with the mid-region of each blade; and   extracting power from the non-uniform fluid flow using the plurality of blades by extracting a greater average power per mass flow rate over the tip region of each blade than an average power per mass flow rate extracted over the a mid-region of each blade.   
     
     
         18 . The method of  claim 17 , wherein the rotor has an axis of rotation, and wherein each blade has a value of power extraction per unit mass flow rate at a radial position along a blade axis that varies as a function of the distance of the radial position from the rotor axis of rotation when exposed to the non-uniform fluid velocity profile. 
     
     
         19 . The method of  claim 17 , wherein, for each blade, an average value of power extraction per mass flow rate for radial positions along the blade axis in the tip region is between 20% and 45% greater than an average value of power extraction per mass flow rate for radial positions along the blade axis from the blade root to the blade tip. 
     
     
         20 . The method of  claim 17 , wherein the turbine shroud further includes one or more mixing devices disposed downstream of the rotor and extending downstream. 
     
     
         21 . The method of  claim 20 , wherein the one or more mixing devices comprise mixer lobes. 
     
     
         22 . The method of  claims 20 , wherein the axial flow fluid turbine further includes an ejector shroud downstream of the turbine shroud. 
     
     
         23 . The method of  claim 21 , wherein turbine shroud with mixing devices and the ejector shroud form a mixer-ejector pump, and the wherein the non-uniform flow velocity profile at the rotor plane is created, in part, by the mixer-ejector pump. 
     
     
         24 . The method of  claim 20 , wherein the mixing devices function as flow straighteners to straighten a fluid flow downstream of the rotor. 
     
     
         25 . The method of  claim 17 , wherein the shrouded axial flow turbine generates electricity from the power extracted from the non-uniform fluid flow by the rotor. 
     
     
         26 . A turbine comprising a rotor that (i) is configured to extract energy from a fluid flow characterized by a turbine-induced non-uniform fluid velocity profile across a rotor plane and (ii) includes at least one unevenly-loaded rotor blade having a power-extracting region in which power extraction per mass flow rate at a first radial position relative to an axis of rotation is different than power extraction per mass flow rate at a second radial position relative to the axis of rotation. 
     
     
         27 . The turbine of  claim 26 , wherein an airfoil of the blade at each of the first and second radial positions is configured based on a pitch or a shape of the airfoil to affect the difference between power extraction per mass flow rate at the first radial position and power extraction per mass flow rate at the second radial position. 
     
     
         28 . The turbine of  claim 26 , wherein the turbine-induced non-uniform velocity profile is characterized by a greater flow velocity at the first radial position than at the second radial position and wherein power extraction per mass flow rate at the first radial position is greater than power extraction per mass flow rate at the second radial position. 
     
     
         29 . A method for manufacturing an unevenly-loaded rotor blade, the method comprising:
 identifying along a power extracting region of the blade a first radial position relative to an axis of rotation of the blade having an expected exposure to a greater flow velocity than a second radial position relative to the axis of rotation along the power extracting region of the blade; and   configuring the power-extracting region to affect greater power extraction per mass flow rate at the first axial position than at the second axial position.