Blade tip to shroud clearance for shrouded fluid turbines

Abstract

Shrouded fluid turbines having features for setting, adjusting or controlling a blade tip-shroud clearance are described. Also described are methods for setting, adjusting or controlling a blade tip-shroud clearance in a shrouded fluid turbine.

1 . A shrouded fluid turbine comprising:
 a central hub rotatable about a central axis of the shrouded fluid turbine;   a blade comprising:
 a proximal portion including a blade root coupled to the central hub; 
 a distal portion including a blade tip; and 
 a mid-portion disposed between the proximal portion and the distal portion; 
   a first shroud having an inner surface in proximity to the blade tip; and   an adjustment mechanism configured to adjust a separation between the blade tip and the shroud inner surface by lengthening or shortening a distance between the blade tip and the central hub.   
     
     
         2 . The shrouded fluid turbine of  claim 1 , further comprising an ejector shroud located downstream from the first shroud; wherein the first shroud comprises mixing lobes. 
     
     
         3 . The shrouded fluid turbine of  claim 1 , wherein the adjustment mechanism radially retracts or extends at least a portion of the blade with respect to the central hub. 
     
     
         4 . The shrouded fluid turbine of  claim 3 , wherein the adjustment mechanism retracts or extends at least a portion of the blade telescopically. 
     
     
         5 . The shrouded fluid turbine of  claim 1 , wherein the adjustment mechanism displaces at least the distal portion and the mid-portion of the blade in a radial direction with respect to the central hub. 
     
     
         6 . The shrouded fluid turbine of  claim 1 , wherein the adjustment mechanism comprises a coupling between at least the distal portion of the blade and the proximal portion of the blade that permits at least the distal portion of the blade to be rotationally displaced about a non-radial axis relative to the proximal portion of the blade. 
     
     
         7 . The shrouded fluid turbine of  claim 6 , wherein the adjustment mechanism comprises a hinge coupling the distal portion of the blade and the proximal portion of the blade. 
     
     
         8 . The shrouded fluid turbine of  claim 1 , wherein the adjustment mechanism comprises a hinged coupling that permits at least the proximal portion of the blade to be angularly displaced about a non-radial axis relative to the central hub. 
     
     
         9 . A shrouded fluid turbine comprising:
 a central hub rotatable about a central axis of the shrouded fluid turbine;   a blade comprising:
 a proximal portion including a blade root coupled to the central hub; 
 a distal portion including a blade tip; and 
 a mid-portion disposed between the proximal portion and the distal portion; 
   a first shroud having an inner surface in proximity to the blade tip; and   an inflatable bladder associated with the inner surface and configured to change a spacing between the blade tip and the inner surface by changing a distance between at least a portion of the inner surface and the central axis upon inflation or upon deflation of at least a portion of the inflatable bladder.   
     
     
         10 . The shrouded fluid turbine of  claim 9 , further comprising an ejector shroud located downstream from the first shroud; wherein the first shroud comprises mixing lobes. 
     
     
         11 . The shrouded fluid turbine of  claim 9 , wherein the inflatable bladder is coupleable to the first shroud. 
     
     
         12 . The shrouded fluid turbine of  claim 9 , wherein the inflatable bladder is integral to the first shroud. 
     
     
         13 . The shrouded fluid turbine of  claim 9 , wherein the inflatable bladder comprises a plurality of inflatable chambers. 
     
     
         14 . A shrouded fluid turbine comprising:
 a central hub rotatable about a central axis of the shrouded fluid turbine;   a blade comprising:
 a proximal portion including a blade root coupled to the central hub; 
 a distal portion including a blade tip; and 
 a mid-portion disposed between the proximal portion and the distal portion; 
   a first shroud having inner surface portions in proximity to the blade tip; and   a hinged pitch mechanism configured to lengthen or shorten a distance between at least some of the inner surface portions of the first shroud and the central axis.   
     
     
         15 . The shrouded fluid turbine of  claim 14 , further comprising an ejector shroud located downstream from the first shroud; wherein the first shroud comprises mixing lobes. 
     
     
         16 . The shrouded fluid turbine of  claim 14 , further comprising a control mechanism to control the positions of at least some of the inner surface portions relative to the central axis. 
     
     
         17 . The shrouded fluid turbine of  claim 16 , wherein the control mechanism individually controls the position of each inner surface portion for a plurality of the inner surface portions. 
     
     
         18 - 22 . (canceled) 
     
     
         23 . An energy extraction shrouded fluid turbine comprising:
 a rotor having a central hub rotatable about a central axis of the energy extraction shrouded fluid turbine;   a blade having:
 a proximal portion including a blade root coupled to the central hub; 
 a distal portion including a blade tip; and 
 a mid-portion disposed between the proximal portion and the distal portion; 
   a first shroud having:
 an inner surface in proximity to the blade tip; and 
 mixing lobes; and 
   an adjustment mechanism configured to change a distance between the blade tip and the shroud inner surface by lengthening or shortening a distance between at least a portion of the shroud inner surface and the central axis.   
     
     
         24 . The energy extraction shrouded fluid turbine of  claim 23 , further comprising an ejector shroud located downstream from the first shroud. 
     
     
         25 . The energy extraction shrouded fluid turbine of  claim 23 , wherein the adjustment mechanism comprises an inflatable bladder coupled with the shroud inner surface and configured to change a distance between at least a portion of the shroud inner surface and the central axis upon inflation or upon deflation of at least a portion of the inflatable bladder. 
     
     
         26 . The energy extraction shrouded fluid turbine of  claim 23 , wherein the adjustment mechanism comprises a hinged pitch mechanism. 
     
     
         27 .- 39 . (canceled) 
     
     
         40 . A method of adjusting a blade tip-shroud gap spacing in an energy extraction shrouded fluid turbine including a central hub rotatable about a central axis of the energy extraction shrouded fluid turbine, a blade having a blade tip, and a first shroud having an inner surface in proximity to the blade tip, the method comprising:
 sensing a spacing between the blade tip and at least a portion of the inner surface of the first shroud during rotation of the blade about the central axis; and   changing a distance between the blade tip and the central hub in response to the sensed spacing.   
     
     
         41 . The method of  claim 40 , wherein the energy extraction shrouded fluid turbine further includes an ejector shroud; and wherein the first shroud has mixing lobes. 
     
     
         42 . The method of  claim 40 , wherein sensing the spacing between the blade tip and the shroud inner surface comprises detecting a radial position of the blade tip relative to the central axis or relative to the shroud inner surface. 
     
     
         43 . The method of  claim 40 , wherein sensing the spacing between the blade tip and the shroud inner surface comprises optically detecting a position of the blade tip relative to the central axis or relative to the shroud inner surface. 
     
     
         44 . The method of  claim 40 , wherein changing a distance between the blade tip and the central hub comprises changing the distance between the blade tip and the central hub in real time during operation of the shrouded fluid turbine. 
     
     
         45 . The method of  claim 40 , wherein changing a distance between the blade tip and the central hub comprises extending or retracting at least a portion of the blade with respect to the central hub. 
     
     
         46 . The method of  claim 40 , wherein the at least a portion of the blade is extended or retracted telescopically. 
     
     
         47 . The method of  claim 40 , wherein changing a distance between the blade tip and the central hub comprises displacing at least the blade tip and the blade mid-portion in a radial direction with respect to the central hub. 
     
     
         48 . The method of  claim 40 , wherein changing a distance between the blade tip and the central hub comprises rotating at least the distal portion of the blade relative to the proximal portion of the blade about a non-radial axis. 
     
     
         49 . The method of  claim 40 , wherein changing a distance between the blade tip and the central hub comprises rotating at least the distal portion of the blade relative to the central hub about a non-radial axis. 
     
     
         50 . A method of controlling a blade tip-shroud gap spacing in an energy extraction shrouded fluid turbine including a central hub rotatable about a central axis of the energy extraction shrouded fluid turbine, a blade having a blade tip, and a first shroud having an inner surface in proximity to the blade tip, the method comprising:
 detecting a spacing between the blade tip and at least a portion of the shroud inner surface during rotation of the blade about the central axis; and   actively controlling a distance between the blade tip and the central hub during rotation of the blade based on the detected spacing.   
     
     
         51 . The method of  claim 50 , wherein actively controlling a distance between the blade tip and the central hub during rotation of the blade comprises changing the distance between the blade tip and the central hub in real time during operation of the shrouded fluid turbine. 
     
     
         52 . A method of adjusting a blade tip-shroud gap spacing in an energy extraction shrouded fluid turbine including a central hub rotatable about a central axis of the energy extraction shrouded fluid turbine, a blade having a blade tip, and a first shroud having an inner surface in proximity to the blade tip, the method comprising:
 sensing a spacing between the blade tip and at least a portion of the inner surface of the first shroud during rotation of the blade about the central axis; and   changing a distance between at least a portion of the shroud inner surface and the central axis based on the sensed spacing.   
     
     
         53 . The method of  claims 52 , wherein the first shroud has mixing lobes, and wherein the energy extraction shrouded fluid turbine further includes an ejector shroud downstream of the first shroud. 
     
     
         54 . The method of  claim 52 , wherein changing a distance between at least a portion of the shroud inner surface and the central axis based on the detected spacing occurs during operation of the energy extraction shrouded fluid turbine and during rotation of the blade. 
     
     
         55 . The method of  claim 52 , wherein the energy extraction shrouded fluid turbine further includes an inflatable bladder associated with the shroud inner surface, and wherein changing a distance between at least a portion of the shroud inner surface and the central axis comprises inflating or deflating at least a portion of the inflatable bladder. 
     
     
         56 . The method of  claim 52 , wherein the energy extraction shrouded fluid turbine further includes a hinged pitch mechanism, and wherein the distance between the at least a portion of the shroud inner surface and the central axis is changed using the hinged pitch mechanism. 
     
     
         57 .- 61 . (canceled)