Variable-pitch Stator Vane Skeleton Angle Design
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Solution Overview
Problem
Variable-pitch stator vanes in aircraft turbine engines suffer from air stream misdirection due to truncated blade portions, leading to reduced compressor efficiency and negative impacts on the impeller, which affects overall engine performance.
Innovation Solution
The design of the variable-pitch stator vane features a central portion with a continuous skeleton angle that is matched by the end portions, increasing the curvature to ensure air stream directionality along the entire blade height, with specific chord lengths and junctions to maintain continuity of the skeleton angle between the trailing edge and downstream limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the blade end portions are truncated to leave radial operating clearance, then the blade can be mounted in the compressor, but the air stream misdirection occurs at the end portions
Solution Approach 1:
The skeleton angle varies locally along the blade height: it is constant in the central portion and increases progressively in the end portions. This local variation in geometric property directs the air stream correctly at the truncated end portions while maintaining simplicity in the central region, resolving the contradiction between ease of manufacture and compressor efficiency.
2Length of stationary object
If the blade end portions are truncated, then radial operating clearance is created, but the direction of air stream at end portions does not correspond to predetermined direction
Solution Approach 1:
The skeleton angle transitions from a static constant value in the central portion to a dynamic progressive value in the end portions. This dynamic geometric adaptation allows the blade to maintain correct air stream directionality despite the fixed truncation, resolving the contradiction between radial clearance and ease of operation.
3Device complexity
If the skeleton angle is constant over the central portion, then the blade structure is simplified, but the air stream misdirection negatively impacts the impeller
Solution Approach 1:
The blade is segmented into two functional zones: a central portion with constant skeleton angle for structural simplicity, and end portions with progressive skeleton angle for correct air stream direction. This segmentation resolves the contradiction by assigning different geometric characteristics to different parts of the blade based on their functional requirements.
Data Source
AI summary
A variable-pitch stator blade includes an airfoil having a central portion with a first chord and a first skeleton line delimited by a leading edge and a trailing edge. An end portion has a second chord and a second skeleton line delimited by the leading edge and a downstream limit. A skeleton angle at a first length I1 of the first chord is defined by a function G1(l1), and the skeleton angle at a second length l2 of the second rope being chord is defined by a function G2(l2). The absolute value of the average increase A2 of G2′(l2) between the leading edge and the downstream limit is greater than the absolute value of the average increase Al of Gl′(l1) between the leading edge and a point P, wherein the first length I1 corresponds to the total length of the second chord.