Erosion indicator for a compressor wheel

1. A centrifugal compressor wheel comprising:

a hub;

a web extending radially from the hub; and

a plurality of blades carried by the wheel;

wherein the web includes an erosion indicator of the wheel,

wherein the erosion indicator comprises at least one rib projecting radially from a peripheral edge of the web at a location of a trailing edge of one of the blades,

wherein the rib presents an axial thickness that is less than an axial thickness of the web so as to form a step between a flat of the rib and a surface of the web from which the blades extend, and

wherein the rib presents a radial extent, the step being provided on an upstream face of the radial extent, and an outer radial face of the radial extent directly facing a diffuser of a compression stage so as to present a radial space therebetween.

2. A centrifugal compressor wheel according to claim 1 , wherein the step presents an axial extent lying in a range 0.5 mm to 1.5 mm.

3. A centrifugal compressor wheel according to claim 1 , wherein the radial extent of the rib lies in a range 0.5 mm to 3 mm.

4. A centrifugal compressor wheel according to claim 1 , wherein the rib extends along a circumference of the web.

5. A turbomachine compression stage comprising:

a compressor wheel according to claim 1 ; and

a casing including an inlet to enable an endoscope to be inserted into the compression stage so as to inspect the wear of the erosion indicator.

6. A turbomachine comprising a compression stage according to claim 5 .

7. A method of determining erosion of a centrifugal compressor wheel of a compression stage comprising:

providing a compressor wheel including

a hub;

a web extending radially from the hub; and

a plurality of blades carried by the wheel;

providing an erosion indicator of the wheel in the web, the erosion indicator including at least one rib projecting radially from a peripheral edge of the web at a location of a trailing edge of one of the blades, the rib presenting an axial thickness that is less than an axial thickness of the web so as to form a step between a flat of the rib and a surface of the web from which the blades extend; and

inserting an endoscope into the compression stage to inspect wear of the erosion indicator of the wheel; and

determining acceptability of the compressor wheel based on the inspected wear of the erosion indicator of the wheel,

wherein the compressor wheel is acceptable if a depth of a furrow at the trailing edge is less than the axial extent of the step.

8. A method according to claim 7 , wherein the endoscope is inserted into the compression stage via an inlet of a casing.

9. A method according to claim 7 , further comprising replacing the compressor wheel when the depth of the furrow is greater than the axial extent of the step.