Self-adjusting seal for rotating turbomachinery

Abstract

A self-adjusting seal has a movable seal member fitted in a groove of a dummy ring along a rotor. The movable seal member is biased outwardly in a radial direction by a disc spring, and a gap between the movable seal member and the rotor is large during the start-up or shutdown of rotating turbomachinery. On the other hand, during a rated operation of the rotating turbomachinery, by a fluid having flown into the internal portion of the groove via a gap between a high pressure side end surface of the movable seal member and the groove, the movable seal member is pressed toward the rotor against a biasing force of the disc spring.

1 . A self-adjusting seal for rotating turbomachinery in which a rotational member rotates while confronting a stationary member and energy transfer between the rotational member and a fluid is performed, comprising:
 a movable seal member fitted in a groove provided in the stationary member along the rotational member; and   a biasing member biasing the movable seal member so as to increase a gap between the rotational member and the movable seal member, wherein   at least during a rated operation of the rotating turbomachinery, the movable seal member is pressed toward the rotational member against a biasing force of the biasing member by the fluid having flown into an internal portion of the groove via a gap between a high pressure side end surface of the movable seal member and the groove, and   at least one of a low pressure side end surface of the movable seal member and a wall surface of the groove opposing the low pressure side end surface is subjected to a process for facilitating relative sliding between the low pressure side end surface of the movable seal member and the wall surface of the groove.   
     
     
         2 . The self-adjusting seal for rotating turbomachinery according to  claim 1 , wherein, as the process for facilitating the relative sliding, a lubricating coating is formed on at least one of the low pressure side end surface of the movable seal member and the wall surface of the groove opposing the low pressure side end surface. 
     
     
         3 . The self-adjusting seal for rotating turbomachinery according to  claim 2 , wherein the lubricating coating is formed by application, thermal spraying, or plating. 
     
     
         4 . The self-adjusting seal for rotating turbomachinery according to  claim 2 , wherein the lubricating coating contains a solid lubricant made of at least one of molybdenum disulfide, graphite, tungsten disulfide, graphite fluoride, boron nitride, copper, nickel, lead, tin, silver, tetrafluoroethylene, polyimide, and high density polyethylene. 
     
     
         5 . The self-adjusting seal for rotating turbomachinery according to  claim 4 , wherein a dimple for fixing the solid lubricant is formed on at least one of the low pressure side end surface of the movable seal member and the wall surface of the groove opposing the low pressure side end surface. 
     
     
         6 . The self-adjusting seal for rotating turbomachinery according to  claim 1 , wherein, as the process for facilitating the relative sliding, a corner of the wall surface of the groove opposing the low pressure side end surface of the movable seal member is chamfered. 
     
     
         7 . The self-adjusting seal for rotating turbomachinery according to  claim 1 , wherein, as the process for facilitating the relative sliding, a surface roughness Ra of at least one of the low pressure side end surface of the movable seal member and the wall surface of the groove opposing the low pressure side end surface is set to not more than 6.3 μm. 
     
     
         8 . The self-adjusting seal for rotating turbomachinery according to  claim 1 , wherein a coating made of an abradable material is formed on a surface of the movable seal member opposing the rotational member. 
     
     
         9 . The self-adjusting seal for rotating turbomachinery according to  claim 2 , wherein, as the process for facilitating the relative sliding, a corner of the wall surface of the groove opposing the low pressure side end surface of the movable seal member is chamfered. 
     
     
         10 . The self-adjusting seal for rotating turbomachinery according to  claim 3 , wherein, as the process for facilitating the relative sliding, a corner of the wall surface of the groove opposing the low pressure side end surface of the movable seal member is chamfered. 
     
     
         11 . The self-adjusting seal for rotating turbomachinery according to  claim 4 , wherein, as the process for facilitating the relative sliding, a corner of the wall surface of the groove opposing the low pressure side end surface of the movable seal member is chamfered. 
     
     
         12 . The self-adjusting seal for rotating turbomachinery according to  claim 5 , wherein, as the process for facilitating the relative sliding, a corner of the wall surface of the groove opposing the low pressure side end surface of the movable seal member is chamfered.