Turbomachine Blade Lug and Notch Axial Retention
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Solution Overview
Problem
Existing turbine engine blade and rotor disk configurations result in significant leaks, high mass, and mechanical stresses due to large radial distance and radial play, leading to inefficient operation and assembly challenges.
Innovation Solution
A turbine engine blade design featuring a foot with an upstream rim and platform, including a lug that engages a disc locking notch for axial retention, reducing stilt height and radial play, and enhancing assembly orientation, thereby reducing mass and leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the radial distance between the disc tooth and blade platform (stilt height) is reduced, then the blade mass and disc mass are reduced, but the mechanical stresses on the blade root and disc tooth increase
Solution Approach 1:
The locking notch is designed to engage the lug on the blade platform before the blade is fully installed, pre-positioning the blade at the correct radial location. This preliminary engagement allows for a reduced stilt height without increasing mechanical stresses, as the locking mechanism distributes the loads appropriately during the installation and operation phases.
Solution Approach 2:
The retention mechanism is segmented into two distinct functions: the locking notch provides radial positioning and orientation, while the flange provides axial retention. This segmentation allows the stilt height to be minimized for reduced mass, while the flange compensates for any stress concerns by providing dedicated axial support.
2Weight of moving object
If the stilt height is reduced, then the blade mass and disc mass are reduced, but the leakage between adjacent blades increases
Solution Approach 1:
The locking notch is positioned asymmetrically on the disc tooth, and the corresponding lug on the blade platform is designed to engage it in a specific orientation. This asymmetric design ensures that the blade platform maintains optimal positioning relative to adjacent blades, minimizing leakage paths while allowing reduced stilt height for lower mass.
3Loss of energy
If the radial play between the platform and disc tooth is reduced, then air leaks are minimized, but the assembly complexity increases
Solution Approach 1:
The locking notch and flange are merged into a single integrated retention mechanism. The locking notch simultaneously provides radial positioning, orientation guidance, and contributes to reducing radial play, while the flange handles axial retention. This merging reduces assembly complexity compared to having separate mechanisms for each function.
4Ease of operation
If the bosses and cavities mechanism is used to prevent opposite orientation mounting, then the aerodynamic orientation is ensured, but the stilt height increases
Solution Approach 1:
Instead of using bosses on the disc tooth that extend into cavities on the blade platform (which increases stilt height), the design is inverted: the locking notch is cut into the disc tooth and engages with a lug on the blade platform. This inversion allows the blade to be retained closer to the disc, reducing stilt height while maintaining orientation control through the asymmetric locking geometry.
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a mobile vane (34) for a turbine engine, comprising a root (41) designed to be inserted into a receiving element (62) of a rotor disk (38) for a turbine engine, a platform (48) carried by the root (41), and a blade (42) extending from the platform (48). The platform (48) comprises an upstream edge (50). According to the invention, the upstream edge (50) comprises a lug (54) for engaging in a locking notch (64) of the disk in such a way as to hold the vane (34) axially in relation to the disk (38), according to the longitudinal direction (XX) of the receiving element (62).