Variable-Pitch Stator Vane Platform Bumps for Secondary Flow Control
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Solution Overview
Problem
Existing variable-pitch stator blades in turbomachines suffer from inefficiencies due to secondary flows caused by variations in airflow direction, leading to reduced compressor performance and increased energy consumption.
Innovation Solution
The design of variable-pitch stator blades with asymmetrical platforms featuring bumps on the airflow guidance surfaces, which help guide and stabilize airflow, minimizing secondary flows and enhancing compressor efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable-pitch stator blades are used to adjust airflow direction, then adaptability to different flight conditions is improved, but secondary flows and separation occur leading to reduced compressor performance
Solution Approach 1:
The patent applies 3D contouring with hollows and bumps at specific locations on the blade surfaces (leading edge, trailing edge, and platform areas) to locally modify airflow behavior. These localized geometric features create controlled vortices that counteract harmful secondary flows and separation, maintaining attached flow across a range of blade angles and improving compressor performance while preserving variable-pitch adaptability
Solution Approach 2:
The patent transitions from traditional 2D blade cross-sections to 3D contoured surfaces by adding hollows and bumps in the spanwise direction. This dimensional enhancement allows the blade to actively manage three-dimensional secondary flows and tip vortices, controlling flow separation and improving performance across varying pitch angles
2Loss of energy
If 3D contouring with hollows and bumps is applied to fixed rectifier blades, then secondary flows are limited, but the solution is suboptimal for variable stator vanes due to pivot-induced flow variations
Solution Approach 1:
The patent makes the contouring features dynamic by positioning them on variable-pitch stator blades that can rotate about their platforms. The hollows and bumps remain fixed relative to the blade structure, but their orientation and effectiveness adapt as the blade pitch angle changes, allowing continuous optimization of flow control across the full range of motion
Solution Approach 2:
The contouring design serves multiple functions simultaneously: it controls secondary flows, reduces tip vortices, prevents flow separation, and maintains effectiveness across varying pitch angles. This multi-functional approach allows a single geometric configuration to address multiple flow control needs throughout the blade's operational range
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 solution improves compressor performance and reduces fuel consumption by limiting secondary flows, thereby reducing the environmental impact of aircraft.
Implementation Method 1
The airflow may exhibit unwanted secondary flows, notably due to separation at the upper and lower surfaces
Data Source
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AI summary
The invention relates to a variable vane (9; 109) of a turbine engine stator, the vane comprising: a blade (11) for guiding an air stream; and one or two platforms (26) disposed at one end or at both ends of the blade, the platform or platforms comprising a surface (26.1) for guiding the air stream, the surface comprising a first disc portion (30.1) on the pressure side (11.3) and a second disc portion (30.2) on the suction side (11.4); characterised in that the first or second disc portion or at least one of the first or second disc portions comprises a boss (32).