Cmc turbine engine blades and a rotor wheel for a turbine engine and a turbine engine integrating them

Abstract

A rotor wheel of a turbine engine includes a plurality of CMC blades each having a first portion constituting a blade airfoil and root and made as a single piece with a second portion forming an outer platform. The blades are held under twisting prestress by mutual engagement via contact zones between the outer platforms of adjacent blades, and the contact zones that are situated on opposite sides of the outer platform of a blade are defined by at least one insert that is integrated in the outer platform and that is, for example, made of a carbon-based material.

Description

BACKGROUND OF THE INVENTION[0001]The invention relates to turbine engine blades made of ceramic matrix composite (CMC) material, i.e. comprising fiber reinforcement that is densified with a ceramic matrix.[0002]The intended field is that of gas turbine blades for aeroengines or for industrial turbines, and more particularly the blades of rotor wheels of compressor or turbine stages, such as the blades of a low pressure (LP) turbine.[0003]Proposals have already been made to produce turbine engine blades out of CMC. Reference may be made in particular to the following documents: US 2011 / 0293828, US 2011 / 0311368, and US 2008 / 0229567.[0004]Turbine engine blades are exposed to excitations that are produced by their environment, in particular the wake effect from nozzles (stationary vanes) or by unbalance. These excitations give rise to vibratory stresses that it is desirable to damp in order to avoid a blade breaking.[0005]With wheels that have metal blades, it is known to damp vibration...

AI Technical Summary

Benefits of technology

[0012]The invention is remarkable in particular by inserts being integrated in the outer platforms of CMC blades in order to define mutual contact zones between the outer platforms of blades that are mounted with twisting prestress in the rotor wheel. This makes it possible for a material to be selected for these zones in contact that is other than a CMC material and that presents good resistance to wear by friction, and that also advantageously presents good behavior at high temperatures and good resistance to oxidation.

Problems solved by technology

Turbine engine blades are exposed to excitations that are produced by their environment, in particular the wake effect from nozzles (stationary vanes) or by unbalance.

Such a solution cannot be envisaged for blades made of CMC because of the difficulty firstly in binding a metal coating to a CMC material, and secondly of guaranteeing that said binding is long-lasting, given the difference between the coefficients of thermal expansion of the metal coating and of the CMC material.

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