Axial turbine

Abstract

An axial turbine includes a plurality of ribs provided in such a way as to be sandwiched between the diaphragm outer ring and the axial seal fin in the gap between the shroud and the diaphragm outer ring, the ribs being extended from the diaphragm outer ring toward the shroud in the radial direction of the rotor and in the direction of the rotation axis thereof, and a guide plate provided in such a way as to be present along the axial seal fin and a face of the diaphragm outer ring, opposed to the rotor, so as to be extended in the rotation radial direction of the rotor.

What is claimed is: 
     
         1 . An axial turbine comprising:
 a rotatably supported rotor;   a bucket fixed to the rotor;   a shroud provided at the tip of the bucket;   a diaphragm outer ring opposed to the shroud with a gap interposed therebeteen;   a radial seal fin provided in such a way as to protrude from the diaphragm outer ring in the radial direction of the rotor in the gap between the diaphragm outer ring and the shroud;   an axial seal fin provided in such a way as to protrude from the diaphragm outer ring in the direction of a rotation axis of the rotor in the gap between the shroud and the diaphragm outer ring;   a plurality of ribs provided in such a way as to be sandwiched between the diaphragm outer ring and the axial seal fin in the gap between the shroud and the diaphragm outer ring, the ribs being extended from the diaphragm outer ring toward the shroud in the radial direction of the rotor and in the direction of the rotation axis thereof; and   a guide plate provided in such a way as to be present along the axial seal fin and a face of the diaphragm outer ring, opposed to the rotor, so as to be extended in the rotation radial direction of the rotor.   
     
     
         2 . The axial turbine according to  claim 1 , wherein the position of the guide plate is variable in the circumferential direction of the rotor in response to an operation state of the axial turbine. 
     
     
         3 . The axial turbine according to  claims 1 , wherein the guide plate and the axial seal fin are each provided with a hole penetrating therethrough along the rotation radial direction of the rotor, and the guide plate is linked to the axial seal fin with the use of a guide plate support-member. 
     
     
         4 . The axial turbine according to any of  claims 1 , wherein the hole of the guide plate is provided at a position on a side of the guide plate, closer to the shroud than the central part of the guide plate. 
     
     
         5 . The axial turbine according to any of  claims 1 , wherein a face of the guide plate, opposed to the rotor, is disposed on a side of the guide plate, inner than a face of the shroud, adjacent to the bucket, along the radial direction of the rotor. 
     
     
         6 . An axial turbine comprising:
 a rotatably supported rotor;   a bucket fixed to the rotor;   a shroud provided at the tip of the bucket;   a diaphragm outer ring opposed to the shroud with a gap interposed therebeteen;   a radial seal fin provided in such a way as to protrude from the diaphragm outer ring in the radial direction of the rotor in the gap between the diaphragm outer ring and the shroud;   an axial seal fin provided in such a way as to protrude from the diaphragm outer ring in the direction of a rotation axis of the rotor in the gap between the shroud and the diaphragm outer ring;   a plurality of ribs provided in such a way as to be sandwiched between the diaphragm outer ring and the axial seal fin in the gap between the shroud and the diaphragm outer ring, the ribs being extended from the diaphragm outer ring toward the shroud in the radial direction of the rotor and in the direction of the rotation axis thereof;   a guide plate provided in such a way as to be present along the axial seal fin and a face of the diaphragm outer ring, opposed to the rotor, so as to be extended in a rotation radial direction of the rotor;   a first static pressure hole, and a second static pressure hole, provided side by side in the circumferential direction of the rotor, on a face of the guide plate, opposed to the bucket;   a pressure measurement device connected to the first static pressure hole, and the second static pressure hole, respectively; and   a guide-plate driving device for varying the position of the guide plate.   
     
     
         7 . The axial turbine according to  claim 6 , wherein the position of the guide plate is varied via the guide-plate driving device on the basis of data of the pressure measurement device. 
     
     
         8 . The axial turbine according to  claim 6 , wherein a face of the guide plate, opposed to the rotor, is disposed on a side of the guide plate, inner than a face of the shroud, adjacent to the bucket, along the radial direction of the rotor. 
     
     
         9 . The axial turbine according to any of  claims 6 , wherein the guide-plate driving device is provided so as to cover the first static pressure hole and the second static pressure hole. 
     
     
         10 . The axial turbine according to any of  claims 6 , wherein the guide-plate driving device is provided at a position closer to a face on the opposite side of the face provided with the first static pressure hole and the second static pressure hole, than the center part of the guide plate.