Frangible Impeller Containment Fasteners for Torsional Load Isolation
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Solution Overview
Problem
Flight-based turbo machinery with mixed flow compressor impellers faces challenges in managing high-energy fragments released during impeller failures, which can cause damage to containment structures due to transferred loads.
Innovation Solution
The use of frangible support fasteners and anti-shear pins in the compressor assembly to isolate the impeller and diffuser from support structures when torsional loads exceed a predetermined limit, preventing damage by decoupling these components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid support fasteners are used to secure support structures to the diffuser, then structural strength and stability are improved, but damage to support structures occurs when impeller failure generates excessive torsional loads
Solution Approach 1:
The support fasteners are designed with frangible characteristics, changing their mechanical properties to allow controlled failure at predetermined torsional loads. This enables the fasteners to maintain structural integrity during normal operation but fail safely when excessive loads are generated by impeller failure, preventing damage to support structures while maintaining strength during normal use.
2Stability of the object's composition
If the diffuser is rigidly connected to support structures, then structural stability is improved, but high-energy fragments from impeller failure transfer excessive loads to the support structures
Solution Approach 1:
The connection between the diffuser and support structures is segmented into multiple frangible support fasteners. This segmentation allows the system to maintain stability during normal operation through the collective strength of multiple fasteners, while enabling controlled separation when excessive loads occur, as individual fasteners can fail independently to dissipate energy and prevent catastrophic load transfer.
3Object-affected harmful factors
If frangible support fasteners are used to prevent damage from excessive loads, then protection of support structures is improved, but structural reliability may be compromised under normal operating conditions
Solution Approach 1:
The frangible support fasteners are pre-designed with specific failure characteristics and predetermined load thresholds. This preliminary design ensures that the fasteners will reliably maintain structural integrity during normal operating conditions while automatically failing at safe, predetermined load levels during impeller failures, thus protecting support structures without compromising normal operational reliability.
Data Source
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AI summary
A compressor assembly (24) of a gas turbine engine (10) of an aircraft includes an impeller (52) configured to rotate about an engine central longitudinal axis (14), and a diffuser (64) positioned at a compressor outlet (62) fluidly downstream of the impeller (52). One or more support structures (82) are secured to the diffuser via a plurality of support fasteners (84). The plurality of support fasteners (84) are configured to be frangible when torsional loads from the diffuser (64) on the one or more support structures (82) exceed a predetermined limit, thereby isolating the impeller (52) and the diffuser (64) from the one or more support structures (82).