Alsthom

Gec Alsthom Electromecanique S.a.

Pierre Bourcier

Gilbert Riollet

An arrangement for clipping stress peaks in the anchoring of a turbine blade including a root that is shaped like a Christmas tree, that includes tangs, and that is received in a correspondingly-shaped groove in a disk so as to anchor the blade thereto, wherein the outline of each tang, on the extrados side of the blade root, is such that the clearance for mounting the root in its groove, on the extrados side, is not uniform but rather it includes at least one zone in which the clearance varies, the zone corresponding to a zone of the tang in question where, if the disk-and-blade assembly were rotating at its rated speed of rotation, there would otherwise occur a stress peak relative to the mean stress along the tang if the blade were mounted with constant clearance along the entire length of the tang, the varying clearance varying along the at least one zone with the same sign as the stress peak.

Arrangement for clipping stress peaks in a turbine blade root

Moving blading for a steam turbine, the blading comprising blades (1) having respective bodies (3) provided with caps or fins (4), said caps or fins (4) on adjacent blades coming into contact at least during rotation of the blading over a plane surface which is substantially parallel to the radial axis (Z'Z) of the blade and giving rise to blade body twisting by virtue of said contacts (7, 8), the blading being characterized in that, in addition to the contacts (7 and 8) between adjacent caps or fins (4), it includes a link which is provided by means of additional contacts (A, A') free to slide rectilinearly in a plane corresponding to the plane of each cap or fin (4) along an axis which is substantially perpendicular to the axis of rotation OO' of the blading, said additional contacts (A, A') being situated at a relatively large distance from said contacts (7, 8) which give rise to twisting. The invention improves the vibration properties of the blades.

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Paris, France

Pierre Bourcier