Auxiliary Vanes for Compressor Incidence Management
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Solution Overview
Problem
Variable cycle gas turbine engines face performance and efficiency issues due to negative incidence in high pressure compressor stator vanes, leading to flow separation and vibratory modes that reduce engine performance and vane lifespan.
Innovation Solution
The implementation of a system with auxiliary vanes interdigitated with main vanes in the high pressure compressor, forming a flow channel between the pressure side of the auxiliary vanes and the suction side of the main vanes to manage flow incidence, preventing separation and maintaining a positive angle of incidence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If high pressure compressor stator vanes operate at negative incidence to accommodate mixed flight conditions, then the engine can operate across subsonic, transonic and supersonic regimes, but flow separation occurs on the pressure surface causing performance loss and vibratory modes
Solution Approach 1:
A row of auxiliary vanes is introduced as an intermediary element between the inlet flow and the main stator vanes. These auxiliary vanes pre-condition the flow by reducing the negative incidence angle before it reaches the main vanes, preventing flow separation while allowing the engine to operate across mixed flight conditions.
Solution Approach 2:
The stator vane system is segmented into two functional rows: auxiliary vanes that handle flow conditioning and incidence management, and main stator vanes that perform primary compression. This segmentation allows each row to be optimized for its specific function, with auxiliary vanes dedicated to preventing flow separation.
2Reliability
If auxiliary vanes are added to manage negative incidence, then flow separation is prevented and vane life is extended, but the device complexity increases
Solution Approach 1:
The auxiliary vanes are merged with the existing stator vane structure, sharing the same support framework and casing integration. This merging approach minimizes additional complexity by utilizing existing structural elements rather than creating entirely separate systems.
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
This approach effectively reduces mechanical excitation, enhances compressor performance, and extends the life of high pressure compressor vanes by maintaining a non-negative angle of incidence, thereby improving engine efficiency and operability across a range of flight conditions.
Implementation Method 1
A flow channel is defined between a pressure side of an auxiliary vane of the second row of auxiliary vanes and a suction side of an adjacent main vane of the first row of main vanes
Data Source
AI summary
An apparatus and method of managing negative incidence in a compressor is provided. The apparatus includes a first row of stationary main vanes, and a second row of stationary auxiliary vanes extending radially inwardly from a stationary casing of the compressor proximate the leading edges of the main vanes. A flow channel is defined between a pressure side of an auxiliary vane of the second row of auxiliary vanes and a suction side of an adjacent main vane of the row of main vanes.