Turbomachine Blade Root Foil With Oblique Tabs Against Axial Wear
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Solution Overview
Problem
Conventional foils for turbomachine rotor blades are prone to axial movement and radial tab wear, leading to premature disengagement and increased maintenance costs due to friction, necessitating frequent rotor removal for repair.
Innovation Solution
A foil with oblique tabs inserted into a housing in the blade root, providing enhanced resistance to friction and preventing axial movement, ensuring stable attachment during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radial tabs are used to prevent foil disengagement from blade root, then axial movement is restricted, but the radial tabs wear and break due to friction from repeated axial displacement
Solution Approach 1:
The patent changes the geometric parameters of the blocking tabs from radial orientation to oblique orientation at angles of 15-45 degrees relative to the radial direction. This angular parameter modification allows the tabs to engage with corresponding features on the blade root at an angle that reduces direct friction during axial displacement, thereby extending service life while maintaining attachment reliability
Solution Approach 2:
The invention transitions from a single radial blocking mechanism to a multi-dimensional engagement system where oblique tabs work in conjunction with the radial geometry of the blade root cavity. The oblique tabs engage with angled surfaces or features, creating a three-dimensional interference fit that prevents disengagement while distributing wear across multiple contact points rather than concentrating friction on simple radial edges
2Strength
If foils are mounted to reduce wear at contact interfaces, then blade root wear is limited, but the foils themselves become subject to friction and axial displacement damage
Solution Approach 1:
The oblique blocking tabs act as intermediary elements between the foil and the blade root. Instead of the foil directly sliding against radial features of the blade root, the oblique tabs mediate the connection, engaging with angled surfaces that convert harmful axial friction into more favorable oblique contact forces, thereby protecting both the foil and blade root from direct wear
Solution Approach 2:
The patent converts the harmful effect of axial displacement and friction into a beneficial self-locking mechanism. The oblique geometry of the tabs causes axial movement to generate increased engagement force rather than wear, as the angled contact surfaces convert the sliding motion into a wedging action that tightens the connection between foil and blade root
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The oblique tab design enhances foil robustness, reducing maintenance costs and extending turbomachine service life by minimizing foil disengagement and wear, thereby improving flight safety.
Implementation Method 1
the friction generated by the repeated axial displacement of the foils has the effect of severing them
Data Source
AI summary
A foil for a rotating blade of a turbomachine, configured to be mounted to a blade root of the rotating blade and including an overall U-shaped cross-section formed by two lateral legs connected through a lower surface, the lower surface covering a lower face of the blade root, the lateral legs each covering at least part of two lateral flanks of the blade root; and a blocking system for prohibiting at least some of relative movements between the blade root and the foil, the blocking system including at least one oblique tab, partially cut out of a lower surface of the foil and forming, with respect to the lower surface of the foil, a tilted plane protrusion able to be inserted into a housing formed in a lower face of the blade root.