Axial Turbomachine Compressor Drum with Dual Means of Blade Fixing

Abstract

The present application relates to a rotor drum of a low-pressure compressor of an axial turbomachine. The drum includes a wall generally symmetrical in revolution about an axis and following a generally curved profile. The wall is configured to support a plurality of blade rows. A first blade row is formed by an annular platform integrally formed with the wall at the peak of its profile in relation to the axis; and a second blade row directly downstream of the first; and a third blade row directly upstream of the first; are formed by one or more blade-retaining grooves formed on the wall. The first blade row and the drum form an integral assembly, eliminating certain vibrations. Anchoring the blades is hybrid or mixed. The rotor may be mounted in a housing with ring-shaped stators.

I claim: 
     
         1 . A rotor drum of an axial turbomachine, comprising:
 a wall generally symmetrical in revolution about an axis thereof and having a generally curved profile, the wall being configured to support a plurality of blade rows;   a first blade row formed by an annular platform integrally formed with the wall at a peak of the profile thereof in relation to the axis; and   at least one second blade row directly downstream of the first blade row and a third blade row directly upstream of the first blade row, the second blade row being formed by one or more blade-retaining grooves formed on the wall.   
     
     
         2 . The rotor drum in accordance with  claim 1 , wherein the outer surfaces of the retaining grooves are at an average distance from the axis which is less than the average distance from the platform of the first row to the axis. 
     
     
         3 . The rotor drum in accordance with  claim 1 , wherein the wall comprises:
 a set of annular ribs on the outer surface of the wall configured to mate with an annular layer of abradable material, so as to provide a seal, the set of annular ribs being located axially between the first blade row and the second blade row and between the first blade row and the third blade row.   
     
     
         4 . The rotor drum in accordance with  claim 1 , wherein the wall comprises:
 a set of annular ribs on the outer surface of the wall configured to mate with an annular layer of abradable material, so as to provide a seal, the set of annular ribs being located axially between the first blade row and the second blade row or between the first blade row and the third blade row.   
     
     
         5 . The rotor drum in accordance with  claim 3 , wherein the minimum distance of the peaks of one set of ribs relative to the axis is greater than the maximum distance from the axis of the outer surfaces of the adjacent retaining grooves. 
     
     
         6 . The rotor drum in accordance with  claim 1 , wherein the blades of the first blade row are welded to the platform of the first blade row. 
     
     
         7 . The rotor drum in accordance with  claim 1 , wherein the platform of the first blade row includes blade stubs on which are welded blade extensions, the height of the blade stubs being more than 10% of the radial height of the first blade row. 
     
     
         8 . The rotor drum in accordance with  claim 1 , wherein the platform of the first blade row includes blade stubs on which are welded blade extensions, the height of the blade stubs being more than 25% of the radial height of the first blade row. 
     
     
         9 . The rotor drum in accordance with  claim 1 , wherein the blades of the first blade row are at least partially cut into the body of the unmachined drum. 
     
     
         10 . The rotor drum in accordance with  claim 1 , wherein the general curved profile of wall extends over most of the length of the drum and has a main concavity directed towards the main axis and extending over the major part of the length of the drum, the profile having a radius relative to the axis, which is at a maximum at the first blade row. 
     
     
         11 . The rotor drum in accordance with  claim 1 , wherein the general curved profile of wall extends over most of the length of the drum or has a main concavity directed towards the main axis and extending over the major part of the length of the drum, the profile having a radius relative to the axis, which is at a maximum at the first blade row. 
     
     
         12 . The rotor drum in accordance with  claim 1 , wherein the platform of the first blade row is raised relative to the wall directly upstream and downstream of the first blade row. 
     
     
         13 . The rotor drum in accordance with  claim 12 , wherein the wall comprises:
 two parts extending generally radially under the platform of the first blade row, so that the longitudinal section of the wall at the said platform has a π-shaped profile.   
     
     
         14 . The rotor drum in accordance with  claim 13 , wherein the wall comprises:
 at least one annular stiffener extending radially inwardly at the first blade row in the extension of at least one of the radial parts.   
     
     
         15 . The rotor drum in accordance with  claim 13 , wherein the wall immediately upstream and downstream of the first blade row comprises:
 a substantially constant thickness part which defines an annular space for accommodating a stator inner shell.   
     
     
         16 . The rotor drum in accordance with  claim 1 , further comprising:
 blades of the second blade row and the third blade row, each of the blades comprising:   a root housed in a retaining groove.   
     
     
         17 . The rotor drum in accordance with  claim 1 , further comprising:
 blades of the second blade row or the third blade row, each of the blades comprising   a root housed in a retaining groove.   
     
     
         18 . The rotor drum in accordance with  claim 1 , wherein the retaining grooves are annular along the perimeter of the drum. 
     
     
         19 . An axial turbomachine, comprising:
 a rotor drum, comprising:
 a wall generally symmetrical in revolution about an axis thereof and having a generally curved profile, the wall being configured to support a plurality of blade rows; 
 a first blade row formed by an annular platform integrally formed with the wall at a peak of the profile thereof in relation to the axis; and 
 at least one second blade row directly downstream of the first blade row and a third blade row directly upstream of the first blade row, the second blade row being formed by one or more blade-retaining grooves formed on the wall; 
   wherein the rotor drum is a low-pressure compressor rotor having essentially three annular rows of rotor blades.