Inner peripheral surface shape of casing of axial-flow compressor

Abstract

A generating line of a casing surrounding an outer periphery of vanes of a stator disposed downstream of a rotor of the axial-flow compressor includes: a recessed region recessed outward in a radial direction from a position forward of a front edge of each of the vanes to a position rearward of a rear edge of the vane; and a protruding region bulging inward in the radial direction at an intermediate position of the recessed region in a front-rear direction thereof. Thus, a distribution of static pressure in the radial direction on a surface of the vane is improved by a first recessed portion forward of the protruding region, and the static pressure on the tip side is raised by a second recessed portion rearward of the protruding region.

1 . An inner peripheral surface shape of a casing of an axial-flow compressor, the casing surrounding an outer periphery of vanes of a stator which are disposed in a radial arrangement and rearwardly of a rotor of the axial-flow compressor, wherein
 a generating line of the casing comprises a recessed region and a protruding region, the recessed region being recessed outward in a radial direction from a position frontwardly of a front edge of each of the vanes to a position rearwardly of a rear edge of the vane, the protruding region bulging inward in the radial direction at an intermediate position of the recessed region in a front-rear direction.   
     
     
         2 . The inner peripheral surface shape of a casing of an axial-flow compressor according to  claim 1 , wherein the recessed region comprises a first recessed portion on a front side, a second recessed portion on a rear side, a first protruding portion continuous to a front portion of the first recessed portion, a second protruding portion forming said protruding region, and a third protruding portion continuous to a rear portion of the second recessed portion. 
     
     
         3 . The inner peripheral surface shape of a casing of an axial-flow compressor according to  claim 2 , wherein the first protruding portion, the first recessed portion, the second protruding portion, the second recessed portion, and the third protruding portion are smoothly continuous to each other. 
     
     
         4 . The inner peripheral surface shape of a casing of an axial-flow compressor according to  claim 1 , wherein each of the vanes is swept so that a tip-side end portion thereof is positioned rearwardly of a hub-side end portion thereof. 
     
     
         5 . The inner peripheral surface shape of a casing of an axial-flow compressor according to  claim 2 , wherein each of the vanes is swept so that a tip-side end portion thereof is positioned rearwardly of a hub-side end portion thereof. 
     
     
         6 . The inner peripheral surface shape of a casing of an axial-flow compressor according to  claim 3 , wherein each of the vanes is swept so that a tip-side end portion thereof is positioned rearwardly of a hub-side end portion thereof.