Abstract:
A wind turbine blade ( 112 ) is situated on a wind turbine ( 100 ). The wind turbine blade ( 112 ) includes a tip portion ( 122 ) and an obstruction removal system ( 200 ). The tip  212  portion ( 122 ) comprises an end wall which defines an opening. The obstruction removal system ( 200 ) is positioned with respect to the blade ( 112 ) so as to remove obstructions from the opening.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter described herein relates generally to wind turbines and, more particularly, to a wind turbine, a rotor blade, and an obstruction removal system for a rotor blade. 
         [0002]    Generally, a wind turbine includes a rotor that includes a rotatable hub assembly having multiple rotor blades. The rotor blades transform wind energy into a mechanical rotational torque that drives one or more generators via the rotor. The generators are sometimes, but not always, rotationally coupled to the rotor through a gearbox. The gearbox steps up the inherently low rotational speed of the rotor for the generator to efficiently convert the rotational mechanical energy to electrical energy, which is fed into a utility grid via at least one electrical connection. Gearless direct drive wind turbines also exist. The rotor, generator, gearbox and other components are typically mounted within a housing, or nacelle, that is positioned on top of a tower. 
         [0003]    During operation of a wind turbine, humidity within ambient air may condense within one or more rotor blades. Such condensation may damage the rotor blades. For example, if lightning strikes a rotor blade, condensation within the rotor blade may vaporize and cause a sudden increase in pressure within the blade such that the blade may crack or fail. Accordingly, at least some known rotor blades include a drain opening within a tip portion of each rotor blade. Condensation and/or other fluids may be removed from the rotor blades through such drain openings by gravity and/or by a centrifugal force generated by a rotation of the rotor blades. However, during operation of the wind turbine, one or more drain openings may become obstructed due to an accumulation of particulates proximate to and/or within the drain openings. Such obstructions may reduce an effectiveness of the drain openings in removing condensation or other fluids from the rotor blades. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    In one embodiment, a rotor blade for a wind turbine is provided that includes a tip portion including an end wall defining an opening. An obstruction removal system is positioned with respect to the rotor blade and the obstruction removal system is configured to remove obstructions from the opening. 
         [0005]    In another embodiment, an obstruction removal system is provided for use in a wind turbine rotor blade having an opening defined in an end wall. The obstruction removal system includes a movable component and a pin coupled to the movable component. The movable component is configured to position the pin in the opening to remove obstructions from the opening. 
         [0006]    In yet another embodiment, a wind turbine is provided that includes a rotor blade configured to rotate about an axis. The rotor blade includes a tip portion that includes an end wall having an opening defined therein. The wind turbine also includes an obstruction removal system positioned with respect to the rotor blade that is configured to remove obstructions from the opening. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a perspective view of an exemplary wind turbine. 
           [0008]      FIG. 2  is a partial sectional view of an exemplary nacelle suitable for use with the wind turbine shown in  FIG. 1 . 
           [0009]      FIG. 3  is a cross-sectional view of an exemplary obstruction removal system in a retracted position suitable for use with the wind turbine shown in  FIG. 1 . 
           [0010]      FIG. 4  is a cross-sectional view of the exemplary obstruction removal system in an extended position shown in  FIG. 3 . 
           [0011]      FIG. 5  is a cross-sectional view of a rotor blade including an alternative obstruction removal system suitable for use with the wind turbine shown in  FIG. 1 . 
           [0012]      FIG. 6  is a cross-sectional view of a portion of the alternative obstruction removal system shown in  FIG. 5 . 
           [0013]      FIG. 7  is a cross-sectional view of another alternative obstruction removal system suitable for use with the wind turbine shown in  FIG. 1 . 
           [0014]      FIG. 8  is a cross-sectional view of yet another alternative obstruction removal system suitable for use with the wind turbine shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    The embodiments described herein provide obstruction removal systems for use with a wind turbine rotor blade. In one embodiment, the obstruction removal system includes a rotatable component coupled to a pin. When gravity and/or a centrifugal force generated by a rotation of the rotor blade acts on the rotatable component, the pin is displaced into and/or through an opening defined in an end wall of a rotor blade tip portion. In another embodiment, the obstruction removal system includes a cable that is coupled to an extension device. When an activation device is operated, the cable is retracted to operate the extension device. A pin within the extension device is displaced into and/or through the opening in the end wall. In another embodiment, the obstruction removal system includes a mass that pivots about a fulcrum when gravity and/or a centrifugal force generated by the rotation of the rotor blade acts upon the mass. When the mass pivots, a pin is displaced into and/or through the opening in the end wall. In yet another embodiment, a motor extends and retracts a pin into and out of the opening in the end wall. As such, the embodiments described herein facilitate using an obstruction removal system to displace a pin into and/or through the opening to dislodge and/or remove particulates or other obstructions from the opening. Moreover, the obstruction removal systems described herein do not require electricity to operate, thus simplifying a construction, an operation, and/or a configuration of the wind turbine, the rotor blades, and/or the obstruction removal systems. 
         [0016]      FIG. 1  is a schematic view of an exemplary wind turbine  100 . In the exemplary embodiment, wind turbine  100  is a horizontal-axis wind turbine. Alternatively, wind turbine  100  may be a vertical-axis wind turbine. In the exemplary embodiment, wind turbine  100  includes a tower  102  extending from and coupled to a supporting surface  104 . Tower  102  may be coupled to surface  104  with anchor bolts or via a foundation mounting piece (neither shown), for example. A nacelle  106  is coupled to tower  102 , and a rotor  108  is coupled to nacelle  106 . Rotor  108  includes a rotatable hub  110  and a plurality of rotor blades  112  coupled to hub  110 . In the exemplary embodiment, rotor  108  includes three rotor blades  112 . Alternatively, rotor  108  may have any suitable number of rotor blades  112  that enables wind turbine  100  to function as described herein. Tower  102  may have any suitable height and/or construction that enables wind turbine  100  to function as described herein. 
         [0017]    Rotor blades  112  are spaced about hub  110  to facilitate rotating rotor  108 , thereby transferring kinetic energy from wind  114  into usable mechanical energy, and subsequently, electrical energy. Rotor  108  and nacelle  106  are rotated about tower  102  on a yaw axis  116  to control a perspective of rotor blades  112  with respect to a direction of wind  114 . Rotor blades  112  are mated to hub  110  by coupling a rotor blade root portion  118  to hub  110  at a plurality of load transfer regions  120 . Load transfer regions  120  each have a hub load transfer region and a rotor blade load transfer region (both not shown in  FIG. 1 ). Loads induced to rotor blades  112  are transferred to hub  110  via load transfer regions  120 . Each rotor blade  112  also includes a rotor blade tip portion  122 . 
         [0018]    In the exemplary embodiment, rotor blades  112  have a length of between approximately 30 meters (m) (99 feet (ft)) and approximately 120 m (394 ft). Alternatively, rotor blades  112  may have any suitable length that enables wind turbine  100  to function as described herein. For example, rotor blades  112  may have a suitable length less than 30 m or greater than 120 m. As wind  114  contacts rotor blade  112 , lift forces are induced to rotor blade  112  and rotation of rotor  108  about an axis of rotation  124  is induced as rotor blade tip portion  122  is accelerated. 
         [0019]    A pitch angle (not shown) of rotor blades  112 , i.e., an angle that determines the perspective of rotor blade  112  with respect to the direction of wind  114 , may be changed by a pitch assembly (not shown in  FIG. 1 ). More specifically, increasing a pitch angle of rotor blade  112  decreases an amount of rotor blade surface area  126  exposed to wind  114  and, conversely, decreasing a pitch angle of rotor blade  112  increases an amount of rotor blade surface area  126  exposed to wind  114 . The pitch angles of rotor blades  112  are adjusted about a pitch axis  128  at each rotor blade  112 . 
         [0020]      FIG. 2  is a partial sectional view of nacelle  106  of exemplary wind turbine  100  (shown in  FIG. 1 ). Various components of wind turbine  100  are housed in nacelle  106 . In the exemplary embodiment, nacelle  106  includes three pitch assemblies  130 . Each pitch assembly  130  is coupled to an associated rotor blade  112  (shown in  FIG. 1 ), and modulates a pitch of an associated rotor blade  112  about pitch axis  128 . Only one of three pitch assemblies  130  is shown in  FIG. 2 . In the exemplary embodiment, each pitch assembly  130  includes at least one pitch drive motor  131 . 
         [0021]    As shown in  FIG. 2 , rotor  108  is rotatably coupled to an electric generator  132  positioned within nacelle  106  via a rotor shaft  134  (sometimes referred to as either a main shaft or a low speed shaft), a gearbox  136 , a high speed shaft  138 , and a coupling  140 . Rotation of rotor shaft  134  rotatably drives gearbox  136  that subsequently drives high speed shaft  138 . High speed shaft  138  rotatably drives generator  132  via coupling  140  and rotation of high speed shaft  138  facilitates production of electrical power by generator  132 . Gearbox  136  is supported by a support  142  and generator  132  is supported by a support  144 . In the exemplary embodiment, gearbox  136  utilizes a dual path geometry to drive high speed shaft  138 . Alternatively, rotor shaft  134  is coupled directly to generator  132  via coupling  140 . 
         [0022]    Nacelle  106  also includes a yaw drive mechanism  146  that rotates nacelle  106  and rotor  108  about yaw axis  116  (shown in  FIG. 1 ) to control the perspective of rotor blades  112  with respect to the direction of wind  114 . Nacelle  106  also includes at least one wind measuring device  148  that includes a wind vane and anemometer (neither shown in  FIG. 2 ). In one embodiment, wind measuring device  148  provides information, including wind direction and/or wind speed, to a turbine control system  150 . Turbine control system  150  includes one or more controllers or other processors configured to execute control algorithms. As used herein, the term “processor” includes any programmable system including systems and microcontrollers, reduced instruction set circuits (RISC), application specific integrated circuits (ASIC), programmable logic circuits (PLC), and any other circuit capable of executing the functions described herein. The above examples are exemplary only, and thus are not intended to limit in any way the definition and/or meaning of the term processor. Moreover, turbine control system  150  may execute a SCADA (Supervisory, Control and Data Acquisition) program. 
         [0023]    Pitch assembly  130  is operatively coupled to turbine control system  150 . In the exemplary embodiment, nacelle  106  also includes forward support bearing  152  and aft support bearing  154 . Forward support bearing  152  and aft support bearing  154  facilitate radial support and alignment of rotor shaft  134 . Forward support bearing  152  is coupled to rotor shaft  134  near hub  110 . Aft support bearing  154  is positioned on rotor shaft  134  near gearbox  136  and/or generator  132 . Nacelle  106  may include any number of support bearings that enable wind turbine  100  to function as disclosed herein. Rotor shaft  134 , generator  132 , gearbox  136 , high speed shaft  138 , coupling  140 , and any associated fastening, support, and/or securing device including, but not limited to, support  142 , support  144 , forward support bearing  152 , and aft support bearing  154 , are sometimes referred to as a drive train  156 . 
         [0024]      FIG. 3  is a cross-sectional view of an exemplary obstruction removal system  200  in a retracted position suitable for use with wind turbine  100  (shown in  FIG. 1 ).  FIG. 4  is a cross-sectional view of obstruction removal system  200  in an extended position. In the exemplary embodiment, obstruction removal system  200  is positioned within rotor blade tip portion  122 . Alternatively, obstruction removal system  200  is positioned within any suitable component and/or system of rotor blade  112  and/or any suitable component and/or system of wind turbine  100  associated with rotor blade  112 . 
         [0025]    In the exemplary embodiment, obstruction removal system  200  includes a rotatable component  202  and a pin  204  that is operatively coupled to, such as positioned in contact with rotatable component  202 . In the exemplary embodiment, rotatable component  202  is a cam  205  that has a width  206  that is smaller than a height  208 . Alternatively, rotatable component  202  may be any suitable component that enables obstruction removal system  200  to operate as described herein. In the exemplary embodiment, rotatable component  202  is coupled to rotor blade tip portion  122  by a first support  210  and a second support  212 . Rotatable component  202  includes a first surface  214 , an opposing second surface  216 , and a pivot axis  218  that extends between first surface  214  and second surface  216 . First support  210  is coupled to first surface  214  at pivot axis  218 , and second support  212  is coupled to second surface  216  at pivot axis  218 . Moreover, in the exemplary embodiment, pivot axis  218  is substantially perpendicular to pitch axis  128  (shown in  FIG. 1 ) and is substantially perpendicular to a chord line  220  of rotor blade  112 . Alternatively, rotatable component  202  may have any suitable configuration that enables obstruction removal system  200  to operate as described herein. 
         [0026]    In the exemplary embodiment, pin  204  includes a head portion  222  that is coupled to pivot axis  218  by a spring  224  that biases head portion  222  against a perimeter  226  of rotatable component  202 . Alternatively, pin  204  and/or head portion  222  are biased against and/or coupled to rotatable component  202  by any other suitable component or device. In the exemplary embodiment, pin  204  is positioned at least partially within an opening  228  defined in a guide wall  230 . Moreover, guide wall  230  limits a radial movement of pin  204  such that pin  204  is directed towards and/or through an opening  232  defined in a rotor blade end wall  234  during operation of wind turbine  100 . Opening  232 , in the exemplary embodiment, is in flow communication with an external environment outside rotor blade  112  and with a cavity  235  defined within rotor blade  112  to facilitate draining and/or removing fluid and/or particulates from within cavity  235 . As used herein, the term “radial” refers to a direction substantially parallel to chord line  220  and substantially perpendicular to pitch axis  128 . 
         [0027]    Moreover, in the exemplary embodiment, a first radial stop  236  and/or a second radial stop  238  are coupled to rotor blade tip portion  112  to limit a rotation of rotatable component  202 . More specifically, first radial stop  236  and/or second radial stop  238  may be manufactured from any suitable material that prevents rotatable component  202  from contacting a leading edge  240  and/or a trailing edge  242  of rotor blade  112 . 
         [0028]    During operation of wind turbine  100 , obstruction removal system  200  may alternate between a retracted position (shown in  FIG. 3 ) and an extended position (shown in  FIG. 4 ). In the retracted position, pin  204  is maintained in contact with perimeter  226  of rotatable component  202  by spring  224  such that pin  204  does not extend through opening  232  of rotor blade end wall  234 . As rotor blade  112  rotates about axis of rotation  124  (shown in  FIG. 1 ), gravity and/or a centrifugal force generated by the rotation of rotor blade  112  may cause rotatable component  202  to rotate about pivot axis  218 . As rotatable component  202  rotates, perimeter  226  displaces pin  204  into and/or through opening  232  as pin  204  moves along perimeter  226  to a position of maximum height  208  of rotatable component  202 . Guide wall  230  prevents pin  204  from moving radially such that pin  204  is substantially displaced through opening  232  rather than allowing pin  204  to rotate with rotatable component  202 . Accordingly, if particulates and/or other obstructions have accumulated within and/or proximate to opening  232 , pin  204  facilitates dislodging the particulates and/or obstructions as pin  204  is displaced into and/or through opening  232 . As such, obstruction removal system  200  facilitates maintaining a substantially unobstructed opening  232  within rotor blade end wall  234 , without the use of electrically-driven components, such that condensation and/or any other fluid may drain from rotor blade  112  through opening  232 . 
         [0029]    Moreover, as rotor blade  112  rotates about axis of rotation  124 , a force and/or a direction of gravity and/or of the centrifugal force may vary. Accordingly, rotatable component  202  may rotate back to the retracted position shown in  FIG. 3 , such that spring  224  retracts pin  204  back into rotor blade  112  and away from opening  232 . 
         [0030]      FIG. 5  is a cross-sectional view of rotor blade  112  that includes an alternative obstruction removal system  300  suitable for use with wind turbine  100  (shown in  FIG. 1 ).  FIG. 6  is a cross-sectional view of rotor blade tip portion  122  that includes a portion of obstruction removal system  300 . Components shown in  FIGS. 5 and 6  that are similar to components in  FIGS. 3 and 4  are labeled with the same reference numerals. In the exemplary embodiment, obstruction removal system  300  is positioned at least partially within rotor blade  112 . Alternatively, obstruction removal system  300  is positioned within any suitable component and/or system of wind turbine  100  associated with rotor blade  112 . 
         [0031]    In the exemplary embodiment, obstruction removal system  300  includes an activation device  302  that is positioned within rotor blade root portion  118  and/or within hub  110  (shown in  FIG. 1 ). Alternatively, activation device  302  may be positioned within nacelle  106  or within any suitable component of wind turbine  100  that enables obstruction removal system  300  to operate as described herein. In the exemplary embodiment, activation device  302  is coupled to a cable  304  that extends through a cavity  305  defined within rotor blade  112 . Activation device  302 , in the exemplary embodiment, includes a pull handle (not shown) and/or any other suitable device that may be manually activated by a user. Alternatively, activation device  302  may include a motor and/or any other suitable device that may be manually activated by a user and/or any device that may be automatically activated by turbine control system  150  (shown in  FIG. 2 ) and/or by any other suitable system. 
         [0032]    Cable  304  is coupled to rotor blade  112  by a plurality of coupling mechanisms  306 . Coupling mechanisms  306  may include one or more rings, hoops, hooks, ties, brackets, and/or any other suitable mechanism that enables cable  304  to be coupled within rotor blade  112 . In the exemplary embodiment, coupling mechanisms  306  couple cable  304  within rotor blade  112  proximate to leading edge  240 . Alternatively, cable  304  may be coupled within rotor blade  112  by coupling mechanisms  306  at any suitable location. 
         [0033]    Moreover, in the exemplary embodiment, cable  304  is coupled to an extension device  308  that is positioned within rotor blade tip portion  122 . Referring further to  FIG. 6 , extension device  308 , in the exemplary embodiment, includes a support bar  310  that is coupled to cable  304  at a first end  312 . A second end  314  of support bar  310  is coupled to a pin  316 . A middle portion  318  of support bar  310  is coupled to a fulcrum  320  that is coupled to guide wall  230  such that support bar  310  pivots about fulcrum  320 . A spring  322  is coupled to first end  312  or proximate to first end  312  to bias extension device  308  and/or pin  316  in a retracted position. Pin  316  is positioned at least partially within opening  228  defined within guide wall  230 . Moreover, extension device  308  is movable such that pin  316  may be directed towards and/or through opening  232  defined in rotor blade end wall  234 . 
         [0034]    During operation of wind turbine  100 , obstruction removal system  300  is selectively movable between a retracted position (shown in  FIG. 6 ) and an extended position (not shown). In the retracted position, support bar  310  is biased by spring  322  such that pin  316  does not extend through opening  232  of rotor blade end wall  234 . A user and/or a suitable system may operate activation device  302  to move extension device  308  into an extended position to facilitate removing particulates and/or obstructions from opening  232 . More specifically, activation device  302  at least partially retracts cable  304  such that cable  304  pulls first end  312  towards rotor blade root portion  118 . As first end  312  is pulled towards rotor blade root portion  118 , support bar  310  pivots about fulcrum  320  such that second end  314  is directed towards rotor blade end wall  234 . Second end  314  displaces pin  316  into and/or through opening  232 , thus facilitating dislodging one or more particulates and/or obstructions that may have accumulated within and/or proximate to opening  232 . As such, obstruction removal system  300  facilitates maintaining a substantially unobstructed opening  232  within rotor blade end wall  234  such that condensation and/or any other fluid may drain from rotor blade  112  through opening  232 . 
         [0035]    To retract extension device  308  and/or pin  316 , activation device  302  is operated such that activation device  302  relaxes cable  304 . Spring  322  pulls first end  312  towards rotor blade end wall  234  causing support bar  310  to pivot about fulcrum  320  and retract pin  316  from opening  232 . 
         [0036]      FIG. 7  is a cross-sectional view of another alternative obstruction removal system  400  suitable for use with wind turbine  100  (shown in  FIG. 1 ). Components shown in  FIG. 7  that are similar to components in  FIGS. 3 and 4  are labeled with the same reference numerals. In the exemplary embodiment, obstruction removal system  400  is positioned within rotor blade tip portion  122 . Alternatively, obstruction removal system  400  is positioned within any suitable component and/or system of rotor blade  112  and/or any suitable component and/or system of wind turbine  100  associated with rotor blade  112 . 
         [0037]    In the exemplary embodiment, obstruction removal system  400  includes a mass  402  that is coupled to a first or rear end  404  of a support bar  406 . A second or front end  408  of support bar  406  is coupled to a pin  410 . Moreover, support bar  406  is rotatably coupled at a middle portion  412  to a pivot bar  414  such that support bar  406  may pivot about pivot bar  414  during operation of wind turbine  100 . A first guide post  416  is coupled to rotor blade  112  to limit a rotation of support bar  406  about pivot bar  414  in a first direction, such as a counter-clockwise direction  418 . A second guide post  420  is coupled to rotor blade  112  to limit a rotation of support bar  406  about pivot bar  414  in a second direction that is opposite of first direction  418 , such as in a clockwise direction  422 . 
         [0038]    During operation of wind turbine  100 , obstruction removal system  400  may alternate between a retracted position (shown in  FIG. 7 ) and an extended position (not shown). In the retracted position, support bar  406  is maintained in contact with first guide post  416  and/or at a position between first guide post  416  and second guide post  420  by gravity and/or a centrifugal force generated by a rotation of rotor blade  112 . As such, pin  410  is prevented from extending through opening  232  of rotor blade end wall  234 . As rotor blade  112  rotates about axis of rotation  124  (shown in  FIG. 1 ), gravity may act upon mass  402  such that mass  402 , support bar  406 , and pin  410  rotate about pivot bar  414  in second direction  422  and into the extended position. More specifically, pin  410  is displaced into and/or through opening  232  as pin  410  is rotated in second direction  422 . Second guide post  420  limits a displacement of pin  410  in second direction  422  after pin  410  is displaced into and/or through opening  232 . Accordingly, if particulates and/or other obstructions have accumulated within and/or proximate to opening  232 , pin  410  facilitates dislodging the particulates and/or obstructions as pin  410  is displaced into and/or through opening  232 . As such, obstruction removal system  400  facilitates maintaining a substantially unobstructed opening  232  within rotor blade end wall  234 , without the use of electrically-driven components, such that condensation and/or any other fluid may drain from rotor blade  112  through opening  232 . 
         [0039]    As rotor blade  112  continues to rotate about axis of rotation  124 , a force and/or a direction of gravity and/or of the centrifugal force may vary. Accordingly, mass  402  may rotate back in first direction  418  such that support bar  406  is brought into contact with first guide post  416  and into the retracted position shown in  FIG. 7 . Accordingly, pin  410  may be retracted back into rotor blade  112  and away from opening  232 . 
         [0040]      FIG. 8  is a cross-sectional view of yet another alternative obstruction removal system  500  suitable for use with wind turbine  100  (shown in  FIG. 1 ). Components shown in  FIG. 8  that are similar to components in  FIGS. 3 and 4  are labeled with the same reference numerals. In the exemplary embodiment, obstruction removal system  500  is positioned within rotor blade tip portion  122 . Alternatively, obstruction removal system  500  is positioned within any suitable component and/or system of rotor blade  112  and/or any suitable component and/or system of wind turbine  100  associated with rotor blade  112 . 
         [0041]    In the exemplary embodiment, obstruction removal system  500  includes a motor  502  that is coupled to a support structure  504  within rotor blade tip portion  122 . Motor  502  is coupled to a control system, such as turbine control system  150  (shown in  FIG. 2 ), by a data connection  506 . Data connection  506  may be a wired data connection  506  and/or a wireless data connection  506  such that the control system may communicate with motor  502  wirelessly and/or through wired data connection  506 . Moreover, motor  502  is coupled to a power source (not shown) within rotor blade  112 , hub  110 , nacelle  106  (shown in  FIG. 1 ), and/or within any suitable location of wind turbine  100  by a power conduit  508 . Alternatively or additionally, motor  502  may include and/or may be coupled to a battery and/or any other suitable power storage device (not shown). Support structure  504 , in the exemplary embodiment, may include a wall, a bulkhead, a flange, and/or any other suitable structure that enables motor  502  to be secured within rotor blade  112  and/or within rotor blade tip portion  122 . 
         [0042]    In the exemplary embodiment, a pin  510  is coupled to and/or is at least partially positioned within motor  502 . Moreover, in the exemplary embodiment, pin  510  is substantially cylindrical and is extendable into and/or through opening  232 . Alternatively, pin  510  may be any suitable shape and may be coupled to a lever, a fulcrum, and/or any other suitable structure that enables obstruction removal system  500  to operate as described herein. 
         [0043]    During operation of wind turbine  100 , obstruction removal system  500  may alternate between a retracted position (shown in  FIG. 8 ) and an extended position (not shown). In the retracted position, pin  510  is maintained at least partially within motor  502  such that pin  510  does not extend into and/or through opening  232 . Upon receiving a suitable control signal from the control system, motor  502  extends pin  510  into and/or through opening  232 . Accordingly, if particulates and/or other obstructions have accumulated within and/or proximate to opening  232 , pin  510  facilitates dislodging the particulates and/or obstructions as pin  510  is displaced into and/or through opening  232 . Motor  502  retracts pin  510  from opening  232  upon receiving a suitable control signal from the control system. Alternatively, motor  502  is not controlled by the control system. In such an embodiment, motor  502  may extend and/or retract pin  510  based on an operation of a timer (not shown) that is coupled to motor  502 , and/or based on any other control circuit or device that enables obstruction removal system  500  to operate as described herein. 
         [0044]    The above-described embodiments provide obstruction removal systems for use with a wind turbine rotor blade. More specifically, the obstruction removal systems are used to remove particulates and/or other suitable obstructions that may accumulate proximate to and/or within an opening defined in an end wall of the rotor blade. The obstruction removal systems described herein use gravity and/or a centrifugal force generated by a rotation of the rotor blade to displace a pin into and/or through the opening to dislodge and/or remove any particulates or other obstructions from the opening. Moreover, the obstruction removal systems are configured to automatically operate using gravity and/or the centrifugal force generated by the rotation of the rotor blade. As such, the obstruction removal systems described herein do not require electricity to operate, thus simplifying a construction, an operation, and/or a configuration of the wind turbine, the rotor blades, and/or the obstruction removal systems. 
         [0045]    Exemplary embodiments of a wind turbine, a rotor blade, and an obstruction removal system for a rotor blade are described above in detail. The wind turbine, rotor blade, and obstruction removal system are not limited to the specific embodiments described herein, but rather, components of the wind turbine, rotor blade, and/or obstruction removal system may be utilized independently and separately from other components and/or steps described herein. For example, the obstruction removal system may also be used in combination with other wind turbines or wind turbine components, and is not limited to practice with only the wind turbine and rotor blade as described herein. Rather, the exemplary embodiment can be implemented and utilized in connection with many other wind turbine applications. 
         [0046]    Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing. 
         [0047]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.