AIR ABRASION COVER PLATE FOR CLEARANCE BETWEEN TURBINE IMPELLERS

PROBLEM TO BE SOLVED: To suppress leakage of gas into a cavity of a clearance between a turbine impellers by providing with a tongue shaped part extending the axial direction fitted into a groove of a spacer on one side, and providing with a recessed part received one protrusion extending in the axial direction of an impeller tail part on an opposite side in an axial direction, in a cover plate. SOLUTION: Cover plates 52a disposed on respective circumferential directions around a rotor, extend straightly in an axial direction, and is provided with a cover plate main body 60 formed in an arched shape in a circumferential direction. A tongue shaped part 63 protruded in the axial direction of one axial direction edge end 62 of the cover plate 52a is received in a groove extending a circumferential direction disposed on a spacer. A center recessed part 70 and a terminal recessed part 72 opened to a wall surface of an axial direction are formed on a flange 66 having an inclining wall 68 of an axial direction edge end of an opposite side, the center recessed part 70 is positioned with a dovetail groove of an impeller. When a tail part of the impeller is inserted into the dovetail groove, the protrusion of the tail part is fitted into the center recessed part 70 so as to obstruct circumferential direction operation of the cover plate 52a.