Session: 21-06 Design Methods

Submission Number: 177395

Alternative Tip Joining Technologies for Short Steam Turbine Blades 

In order to reduce vibration level and improve flow efficiency, some steam turbine blades must be joined to their neighbors at the tip. Short injection blades do not have the flexibility required for the use of common bonding technologies such as centrifugal twisting or pre-stressed assembly, which are reserved for long blades. A commonly used junction consists of a riveted shroud at the head of several blades, grouping them into packs. This technology has the following inconvenient: the rivet reduces the space axially available for a rotor-stator labyrinth seal, reducing the efficiency of the stage. The prediction of vibratory behavior is disrupted by the non periodic blade packing. Finally, the manufacturing and inspection of the rivet-shroud contact is not industrially optimal.

The aim of the research is to find an alternative to this riveted shroud technology for short blades. Various solutions have been modeled to verify their feasibility, and compare them to a reference solution, with respect to different criteria: radial tip displacement, stress in the root, circularity of the shroud, stiffness of the assembly.

To achieve this, several approaches were used: simplified analytical modeling, numerical modeling using finite element strategies, and parametric studies. This paper presents these models and crossed-comparisons of the envisaged solutions.

Presenting Author: Lucien Daniel Laboratoire de Tribologie et Dynamique des Systèmes (LTDS)

Presenting Author Biography: Engineering degree at Ecole Centrale de Lyon, now Ph.D studdent.

Authors:

Lucien Daniel Laboratoire de Tribologie et Dynamique des Systèmes (LTDS)
Manuel Collet Laboratoire de Tribologie et Dynamique des Systèmes (LTDS)
Laurent Blanc Laboratoire de Tribologie et Dynamique des Systèmes (LTDS)
Kévin Billon Laboratoire de Tribologie et Dynamique des Systèmes (LTDS)
Denis Guenard BakerHughes