Flexible Bladed Disk Grooves for Blade Root Impact Stress
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Solution Overview
Problem
The ingestion of foreign objects in a one-piece bladed fan disc of a turbojet engine leads to concentrated mechanical stress at the base of the blades, increasing the risk of tearing due to significant bending stress.
Innovation Solution
A one-piece bladed disc design with through grooves around the blade roots and flexible seals in the grooves to reduce stress, allowing the disc to flex and absorb impact, featuring a hub with an upstream and downstream edge and a radial platform with integrated blades, and a seal extending along the external face to maintain flow continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the fan blades are formed as a single integrated piece with the hub (one-piece bladed disc), then the structural rigidity and strength are improved, but the mechanical stress concentration at the blade base increases during foreign object ingestion
Solution Approach 1:
The patent introduces through grooves that segment the monobloc structure at the blade roots, creating localized flexibility zones. These grooves divide the continuous material into regions with different stiffness characteristics, allowing the blade base to flex independently during foreign object ingestion while maintaining overall structural integrity. The grooves effectively segment the rigid monobloc structure into flexible and rigid zones.
Solution Approach 2:
The patent applies local quality by creating through grooves specifically at the blade root regions where stress concentration occurs during foreign object ingestion. These grooves modify the local mechanical properties (reducing stiffness) only where needed, while the rest of the monobloc structure maintains its full rigidity. This localized modification allows the blade base to flex under impact loads without compromising the overall structural strength.
2Adaptability or versatility
If through grooves are formed around the blade roots, then the flexibility and impact resistance are improved, but the structural strength is reduced
Solution Approach 1:
The through grooves segment the monobloc structure into flexible zones at the blade roots and rigid zones in the hub and blade spans. This segmentation allows different parts of the structure to have different mechanical properties optimized for their specific functions: flexibility at the blade roots for impact absorption, and rigidity elsewhere for structural strength.
Solution Approach 2:
The patent creates flexible regions through the grooves that allow the blade root area to deform elastically during foreign object ingestion. These flexible zones act like compliant elements that can absorb impact energy through deformation, while the rest of the structure maintains its rigidity. The grooves effectively create thin-walled flexible sections in the blade root region.
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 design enhances flexibility and reduces mechanical stress at the blade base, minimizing the risk of tearing and maintaining efficient gas flow continuity while reducing pressure losses.
Implementation Method 1
a seal positioned within the groove so as to extend along the radially external face of the platform to ensure continuity of the internal flow channel
Implementation Method 2
The stiffness of the seal is less than the stiffness of the platform. The stiffness of the seal is at most equal to 50% of the stiffness of the platform
Data Source
Figure 1~2
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Figure 5~6
AI summary
The invention relates to a bladed disk (1) of a fan, comprising: a hub (10) comprising an outer radial platform (13) designed so as to define an inner gas flow stream in the turbomachine, a plurality of blades (20) comprising a root (23) connected to the platform (13), a leading edge (21) and a trailing edge (22), a groove formed in the platform (13) around part of the root (23) of each blade (20) in an area adjacent to the leading edge (21) and/or the trailing edge (22), and a joint (30) placed in the groove (15) in such a way that it extends in the extension of the radially outer face (14) of the platform (13) in order to ensure a continuity of the inner flow stream.