Aircraft Compressor Blade Root Asymmetry for Stress Reduction
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Solution Overview
Problem
The existing disk/blade assemblies for aircraft engine compressors experience uneven mechanical stresses at the bearing surfaces and stilt due to incompatible geometry between the blade root and airfoil, leading to design difficulties and inadequate retention of blades.
Innovation Solution
The disk/blade assembly features a blade root with a downstream bearing surface offset circumferentially from the upstream bearing surface, following the airfoil profile, which increases the intersection magnitude and reduces stress unevenness, allowing for enhanced retention and reduced peening pressures by extending the bearing surfaces in the circumferential direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the blade root is extended parallel to the central axis of the disk from upstream to downstream bearing surface, then the blade retention in the radial direction is achieved, but the mechanical stresses at the bearing surfaces and stilt become extremely uneven
Solution Approach 1:
The blade root is designed with asymmetric bearing surfaces where the downstream bearing surface is offset circumferentially from the upstream bearing surface in the given direction of offset. This asymmetric configuration allows the blade root and stilt to follow the airfoil profile, increasing the intersection magnitude and distributing mechanical stresses more evenly across the bearing surfaces and stilt, while maintaining adequate blade retention through the offset geometry
2Reliability
If the bearing surfaces are extended in the circumferential direction to increase retention, then the peening pressures are reduced, but the manufacturing complexity increases
Solution Approach 1:
The invention changes the geometric parameters of the blade root by offsetting the downstream bearing surface circumferentially from the upstream bearing surface. This parameter change allows the bearing surfaces to be extended in the circumferential direction while maintaining a manageable manufacturing process. The offset geometry naturally distributes peening pressures more evenly and enhances retention without requiring complex additional manufacturing steps
Data Source
AI summary
A disk/blade assembly for an aircraft engine compressor is disclosed. The assembly includes a disk and a plurality of blades with hammer attachment. Each blade includes a blade root provided with an upstream bearing surface situated on a leading edge side of the airfoil and a downstream bearing surface situated on a trailing edge side of this airfoil. The disk is provided with a circumferential groove in which the blade root of each of the blades is held by the bearing surfaces. For each of the blades, the downstream bearing surface is offset circumferentially from the upstream bearing surface in a given direction of offset, corresponding to the direction of offset between the trailing edge and the leading edge of the airfoil.