Variable Stator Vanes Gas Turbine Control
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Solution Overview
Problem
Conventional gas turbine engines have a fixed core flow vs. temperature relationship, limiting their power output and efficiency, especially during varying operational conditions and as they deteriorate over time, requiring over-design to accommodate temperature increases.
Innovation Solution
The method involves scheduling the angle of variable stator vanes on a booster compressor to control the core flow and temperature relationship, allowing for increased power output and efficiency by adjusting the vanes based on engine speed and operational parameters, while maintaining constant core turbine entry temperature through fuel flow regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine is physically sized and temperature capability are designed for maximum power output requirements, then the maximum power output capability is improved, but the efficiency during reduced power demands deteriorates
Solution Approach 1:
The patent applies dynamics by making the stator vanes variable rather than fixed. The stator vane angle is dynamically adjusted based on operating conditions (power demand level and air temperature) to optimize engine performance across different operating points. This allows the engine to efficiently operate at both maximum power output and reduced power demands without being over-designed for peak conditions alone.
Solution Approach 2:
The patent changes the geometric parameter of the stator vanes (their angle relative to the axial direction) to control the core flow vs. temperature relationship. By varying the stator vane angle, the engine can shift its operating point on the core flow vs. temperature curve, enabling efficient operation across different power demand levels and air temperatures while maintaining optimal performance.
2Power
If fuel flow is increased to increase power output, then the power output is improved, but the temperature capability limit is exceeded
Solution Approach 1:
The patent changes the stator vane angle parameter to alter the core flow vs. temperature relationship. By adjusting the stator vane angle, the engine can increase core flow without proportionally increasing temperature, allowing power output to be increased while maintaining temperature within capability limits. This provides an additional degree of freedom beyond simple fuel flow control.
3Reliability
If the engine is over-designed to accommodate deterioration over time, then the reliability is improved, but the weight and size increase
Solution Approach 1:
The patent uses dynamic adjustment of stator vane angle to compensate for engine deterioration over time. As components deteriorate and efficiency decreases, the control system adjusts the stator vane angle to maintain the desired core flow vs. temperature relationship, ensuring the engine continues to meet power output requirements without requiring over-design for worst-case deterioration scenarios.
Solution Approach 2:
The patent implements feedback control by monitoring operating conditions (power demand level, air temperature) and adjusting the stator vane angle accordingly. This feedback mechanism allows the engine to adapt to changing conditions and deterioration over time, maintaining reliable operation without requiring excessive design margins that would increase weight and size.
Data Source
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AI summary
A method of controlling a gas turbine engine (10) which has a booster compressor (13), a core compressor, combustion equipment, a core turbine, and a low-pressure turbine (18). The low-pressure turbine also drives an external load having a defined speed characteristic. The booster compressor (13) has one or more rows of variable stator vanes. The method includes: scheduling variation in the angle of the variable stator vanes as a function of the speed of the booster compressor such that the vanes open as the booster compressor speed increases; measuring or setting one or more operational parameters which are determinative of the temperature at entry to the core turbine; and biasing the scheduling of the angle variation of the variable stator vanes as a function of the operational parameter(s) to reduce variation in temperature at entry to the core turbine