Rotor blade having passive bleed path

Abstract

A rotor blade includes a bleed path opening to a suction surface, extending through the blade, exiting to at least one of the suction or a trailing surface, and through which working fluid flows under centrifugal pumping forces when the blade rotates, to passively bleed working fluid from the suction surface.

1 . A rotor blade comprising:
 a root region;   a tip region disposed radially outwardly of the root region;   a leading surface extending between the root and tip regions;   a trailing surface extending between the root and tip regions;   a pressure surface extending between the root and tip regions and the leading and trailing surfaces;   a suction surface extending between the root and tip regions and the leading and trailing surfaces; and   a bleed path opening to the suction surface, extending through the blade, exiting to at least one of the suction or trailing surfaces, and through which working fluid flows under centrifugal pumping forces when the blade rotates, to passively bleed working fluid from the suction surface.   
     
     
         2 . The rotor blade of  claim 1 , wherein the working fluid passively flows through the bleed path under negative pressurization, but the working fluid does not actively flow through the bleed path by positive pressurization from some external pressurizing device or from a path open to the pressure surface. 
     
     
         3 . The rotor blade of  claim 1 , wherein the bleed path includes:
 an inlet in the suction surface to receive working fluid on the suction surface;   a conduit in communication with the inlet to convey the working fluid from the inlet toward the tip region; and   an outlet in communication with the conduit and disposed radially outwardly of the inlet to exhaust the working fluid out of the blade.   
     
     
         4 . The rotor blade of  claim 3 , wherein the bleed path is configured to cause centrifugal pumping forces to pull the working fluid into the inlet, through the conduit, and out of the outlet when the blade rotates. 
     
     
         5 . The rotor blade of  claim 3 , wherein the bleed path is located radially outward of a circumferential axis bisecting the blade. 
     
     
         6 . The rotor blade of  claim 3 , wherein the inlet is a slot extending in a generally radial direction along the blade. 
     
     
         7 . The rotor blade of  claim 3 , further comprising a plurality of the inlet radially spaced from one another in correspondence to radial pressure gradients. 
     
     
         8 . The rotor blade of  claim 3 , wherein the conduit is at least one of shaped or sized to reduce a differential in velocity of working fluid transmitted from the outlet and velocity of working fluid in a free stream adjacent the outlet. 
     
     
         9 . The rotor blade of  claim 3 , wherein the outlet is located in at least one of the suction surface or the trailing surface. 
     
     
         10 . The rotor blade of  claim 3 , wherein the outlet is located radially inward of a radially outermost tip of the blade. 
     
     
         11 . The rotor blade of  claim 1 , wherein the rotor blade is a working member of at least one of an aircraft propeller, a marine propeller, a helicopter rotor, a turbine engine rotor, or a windmill impeller. 
     
     
         12 . A rotor comprising:
 a hub defining a rotational axis of the rotor; and   a rotor blade extending radially outwardly from the hub, and including:
 a root region; 
 a tip region disposed radially outwardly of the root region; 
 a leading surface extending between the root and tip regions; 
 a trailing surface extending between the root and tip regions; 
 a pressure surface extending between the root and tip regions and the leading and trailing surfaces; 
 a suction surface extending between the root and tip regions and the leading and trailing surfaces; and 
 a bleed path opening to the suction surface and including:
 an inlet in the suction surface to receive working fluid on the suction surface; 
 a conduit in communication with the inlet to convey the working fluid from the inlet toward the tip region; and 
 an outlet in communication with the conduit and disposed radially outwardly of the inlet to exhaust the working fluid out of the blade; 
 
 wherein the bleed path is configured such that working fluid flows through the bleed path under centrifugal pumping forces when the blade rotates, to passively bleed working fluid from the suction surface, such that the working fluid passively flows through the bleed path under negative pressurization, but the working fluid does not actively flow through the bleed path by positive pressurization pushed from the inlet toward the outlet from some external pressurizing device or from a path open to the pressure surface. 
   
     
     
         13 . The rotor of  claim 12 , wherein the bleed path is located radially outward of a circumferential axis bisecting the blade, and the inlet is a slot extending in a generally radial direction along the blade. 
     
     
         14 . The rotor of  claim 12 , wherein the outlet is located in at least one of the suction surface or the trailing surface, and is located radially inward of a radially outermost tip of the blade. 
     
     
         15 . The rotor of  claim 12 , wherein the rotor is at least one of an aircraft propeller, a marine propeller, a helicopter rotor, a turbine engine rotor, or a windmill impeller. 
     
     
         16 . A rotor blade comprising:
 a root region;   a tip region disposed radially outwardly of the root region;   a leading surface extending between the root and tip regions;   a trailing surface extending between the root and tip regions;   a pressure surface extending between the root and tip regions and the leading and trailing surfaces;   a suction surface extending between the root and tip regions and the leading and trailing surfaces; and   a bleed path opening to the suction surface and including:
 an inlet in the suction surface to receive working fluid on the suction surface; 
 a conduit in communication with the inlet to convey the working fluid from the inlet toward the tip region; and 
 an outlet in communication with the conduit and disposed radially outwardly of the inlet to exhaust the working fluid out of the blade. 
   
     
     
         17 . The rotor blade of  claim 16 , wherein the bleed path is configured such that working fluid flows through the bleed path under centrifugal pumping forces when the blade rotates, to passively bleed working fluid from the suction surface, and such that the working fluid passively flows through the bleed path under negative pressurization, but the working fluid does not actively flow through the bleed path by positive pressurization from some external pressurizing device or from a path open to the pressure surface. 
     
     
         18 . The rotor blade of  claim 16 , wherein the bleed path is located radially outward of a circumferential axis bisecting the blade, and the inlet is a slot extending in a generally radial direction along the blade. 
     
     
         19 . The rotor blade of  claim 16 , wherein the outlet is located in at least one of the suction surface or the trailing surface, and is located radially inward of a radially outermost tip of the blade. 
     
     
         20 . The rotor blade of  claim 16 , wherein the rotor blade is a working member of at least one of an aircraft propeller, a marine propeller, a helicopter rotor, a turbine engine rotor, or a windmill impeller.