Impeller Containment Joint With Frangible Fasteners
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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 the supporting structure.
Innovation Solution
A containment system is implemented using frangible support fasteners and anti-shear pins to isolate the impeller and diffuser from support structures when torsional loads exceed a predetermined limit, preventing damage to the compressor scroll and bearing support structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If support fasteners are made strong to securely connect diffuser to support structures, then structural stability is improved, but damage propagates to supporting structure during impeller failure
Solution Approach 1:
The support fastener is divided into two functional segments: a frangible portion designed to fail at a predetermined load and a non-frangible portion that remains intact. This segmentation allows the fastener to provide secure connection during normal operation while isolating the supporting structure from failure forces when the impeller breaks, thus resolving the contradiction between structural stability and damage prevention.
2Object-affected harmful factors
If containment structure is rigid to prevent fragment dispersion, then fragment containment is improved, but torsional loads damage the supporting structure
Solution Approach 1:
The containment structure incorporates dynamic elements through the frangible support fasteners that can transition from a connected state during normal operation to a disconnected state during failure. This dynamic characteristic allows the structure to maintain rigidity for fragment containment while automatically becoming flexible or separable when excessive torsional loads occur, preventing damage to the supporting structure.
3Object-affected harmful factors
If support fasteners are made frangible to isolate structures during failure, then damage isolation is improved, but structural reliability during normal operation decreases
Solution Approach 1:
The support fastener applies local quality differentiation by having a frangible portion with specific material properties designed for controlled failure, while the non-frangible portion maintains strong connection properties. This localized differentiation ensures that only the specific frangible section fails during overload conditions, preserving the overall structural reliability during normal operation while enabling damage isolation when needed.
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 system effectively contains impeller fragments, preventing damage to the compressor scroll and bearing support structure by decoupling them from torsional loads, thereby ensuring structural integrity.
Implementation Method 1
The plurality of support fasteners are configured to be frangible when torsional loads from the diffuser on the one or more support structures exceed a predetermined limit, thereby isolating the impeller and the diffuser from the one or more support structures
Implementation Method 2
a plurality of anti-shear pins are positioned between circumferentially adjacent scroll flange bolts of the plurality of scroll flange bolts
Data Source
AI summary
A compressor assembly of a gas turbine engine of an aircraft includes an impeller configured to rotate about an engine central longitudinal axis, and a diffuser positioned at a compressor outlet fluidly downstream of the impeller. One or more support structures are secured to the diffuser via a plurality of support fasteners. The plurality of support fasteners are configured to be frangible when torsional loads from the diffuser on the one or more support structures exceed a predetermined limit, thereby isolating the impeller and the diffuser from the one or more support structures.