Compressor Aerofoil Inflectional Stacking Axis Profile
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Solution Overview
Problem
Conventional aerofoil member stacking profiles in gas turbine engines fail to effectively decouple midspan and endwall flow regions, leading to increased streamline contraction and profile loss, which degrades blade boundary layer performance and triggers trailing edge separation.
Innovation Solution
The aerofoil member features an inflectional stacking axis profile where the projection onto a plane normal to the engine axis intersects the endwalls at angles between 5° to 25°, with turning points that create a convex shape adjacent the endwalls, allowing for tailored transverse flow redistribution and improved flow decoupling between midspan and endwall regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional stacking profiles (circular, parabolic, end stack) are used, then manufacturing simplicity is maintained, but midspan and endwall flow regions cannot be effectively decoupled, leading to increased streamline contraction and profile loss
Solution Approach 1:
The patent applies parameter changes by modifying the stacking axis profile from conventional circular or parabolic shapes to an inflectional profile. This involves changing the mathematical parameters defining the stacking curve to include an inflection point, which fundamentally alters the flow redistribution characteristics while maintaining manufacturing feasibility through standard stacking processes.
Solution Approach 2:
The inflectional stacking profile creates local quality differences by generating distinct flow patterns in different spanwise regions. The profile is designed to produce specific transverse pressure gradients in midspan regions versus endwall regions, allowing tailored flow control where different parts of the blade experience different flow conditions optimized for their respective requirements.
2Stability of the object's composition
If greater lean or sweep is increased to control transverse boundary layer flow, then corner flow stability is improved, but streamline contraction in the midspan region increases, degrading blade boundary layer and triggering trailing edge separation
Solution Approach 1:
The patent changes the stacking profile parameters from monotonic circular or parabolic curves to an inflectional profile with a specific inflection point. This parameter change creates a non-monotonic distribution of transverse pressure gradients that stabilizes corner flow while preventing excessive streamline contraction in midspan regions, thereby maintaining blade boundary layer integrity.
Solution Approach 2:
The inflectional stacking profile effectively segments the blade span into distinct flow regions with different characteristics. The inflection point acts as a divider that creates different transverse pressure gradient zones, allowing independent optimization of corner flow stability and midspan boundary layer performance as if they were separate systems.
3Loss of energy
If inflectional stacking axis profile is used to decouple midspan and endwall flow regions, then profile loss is reduced, but device complexity increases
Solution Approach 1:
The patent reduces profile loss through parameter changes in the stacking profile, specifically by introducing an inflection point that creates favorable transverse pressure gradient distribution. This single parameter modification achieves flow decoupling and loss reduction without requiring complex multi-component systems or additional hardware.
Data Source
AI summary
An aerofoil member that extends between radially inner and radially outer endwalls which define a gas annulus of the compressor. Aerofoil member has a leading edge, a trailing edge, a pressure surface and a suction surface such that successive cross-sections through the aerofoil member transverse to the radial direction provide respective aerofoil sections. The external shape of the aerofoil member is defined by the stacking of the aerofoil sections on a stacking axis which passes through a reference point common to each aerofoil section. The aerofoil member has lean produced by the projection of the stacking axis onto a plane normal to the engine axis intersecting a first one of the endwalls at an angle of from 5° to 25° to the circumferential direction direction such that the pressure surface faces the first endwall.