Gas Turbine Compressor Guide Vane Control for Stall Avoidance
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Solution Overview
Problem
Gas turbine engines experience aerodynamic noise, efficiency loss, and excessive rotor vibration due to stall conditions during varying operating conditions, which existing control methods attempt to avoid by restricting operational conditions, leading to further efficiency and power output impacts.
Innovation Solution
A controller for a gas turbine engine adjusts the angle of variable guide vanes relative to the operational axis based on engine shaft speed, employing a variable guide vane schedule that differentially controls the first and subsequent stages to manage airflow and prevent stall conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If variable guide vanes are rotated to increase blade angle and reduce compressor throat area to avoid stall, then stall condition is reduced, but efficiency and power output are impacted
Solution Approach 1:
The patent applies dynamics by making the guide vane angle adjustable rather than fixed. The guide vane angle is dynamically changed according to operating conditions (speed, load, temperature) to optimize performance across different regimes, resolving the contradiction between stall avoidance and efficiency by adapting the geometry to current operating parameters
Solution Approach 2:
The patent changes physical parameters (guide vane angle, compressor throat area) based on operating conditions. By varying these parameters dynamically, the system maintains optimal performance across different operating regimes, preventing stall while minimizing efficiency losses that would occur with fixed parameter designs
2Object-affected harmful factors
If operational conditions are restricted to avoid stall, then aerodynamic noise and rotor vibration are reduced, but the range of operable conditions is limited
Solution Approach 1:
The system dynamically adjusts guide vane angles based on real-time operating parameters, enabling the compressor to adapt to a wide range of conditions without entering stall. This dynamic adaptation allows operation across extended ranges while maintaining stable flow conditions and avoiding the harmful effects of stall
Solution Approach 2:
The control system uses feedback from operating parameters (speed, load, temperature) to continuously adjust guide vane positioning. This feedback mechanism ensures the compressor operates within stable flow regimes across a broad range of conditions, preventing stall while maximizing operational versatility
3Reliability
If compressor throat area is reduced to prevent stall, then mass flow control is improved, but power output is reduced
Solution Approach 1:
The compressor throat area is made dynamically adjustable through variable guide vanes rather than being fixed. This allows the throat area to be optimized for each operating regime - reduced when needed for stall prevention, and opened wider when conditions permit higher power output, thus resolving the contradiction between reliability and power
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 system effectively reduces the likelihood of stall and associated damage by optimizing airflow through the compressor, allowing the engine to operate over a wider range of conditions while maintaining efficiency and reducing rotor blade loading.
Implementation Method 1
The first variable guide vane is rotatably mounted at a first location on the casing, having a vane axis of rotation at right angles to the operational axis. The adjustment drive is operable to rotate the first variable guide vane about its axis of rotation to a range of angles relative to the operational axis.
Implementation Method 2
A compressor may consist of multiple stages of stator vanes which are non-rotatable about the operational axis, and rotor blades which are rotatable about the operational axis.
Data Source
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AI summary
A controller (300) for a gas turbine engine (10) which operates to a control method. The gas turbine engine (10) comprises a compressor (14) having a casing (50) which extends along, and is centred on, an operational axis (20). An array (48) of compressor blades are coupled to a rotatable engine shaft (22) which extends along the operational axis (20). A first variable guide vane (8a) is axially spaced apart from the compressor blade array (48) along the operational axis (20), wherein the first variable guide vane (8a) is rotatably mounted at a first location (202) on the casing (50), having a vane axis of rotation (121) at right angles to the operational axis (20). The first variable guide vane (8a) is coupled to an adjustment drive (154) operable to rotate the first variable guide vane (8a) about its axis of rotation (121) to a range (A-D) of angles relative to the operational axis (20). The controller (300) is operable to control the rotation of the first variable guide vane (8a) in dependence of engine shaft speed wherein over a first range (A-B) of engine shaft speed the angle of the first variable guide vane (8a) relative to the operational axis (20) decreases with increasing engine speed and over a second range (B-C) of engine shaft speeds the angle of the first variable guide vane (8a) relative to the operational axis (20) : increases with increasing engine speed.