Gas Turbine Blade Tip Clearance Control During Throttle Changes
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Solution Overview
Problem
Gas turbine engines face inefficiencies due to leakage over rotor blade tips, which can be minimized by maintaining a precise clearance between the blade tips and the casing structure, but existing active clearance control systems struggle to adapt effectively to varying operational conditions, particularly during throttle advances and non-cruise conditions.
Innovation Solution
A system utilizing an active clearance control system with a controller and operational data source to dynamically adjust blade tip clearances based on flight and engine parameters, reducing the thrust limit to a de-rated maximum climb thrust during cruise conditions and increasing it to maximum climb thrust during throttle advances or non-cruise conditions, by determining target tip clearances and sending command signals to adjust the shroud structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the tip clearance is reduced to minimize leakage, then engine efficiency is improved, but the risk of blade contact with the shroud structure increases during throttle advances
Solution Approach 1:
The system dynamically adjusts tip clearance based on real-time operational conditions. During cruise conditions, the clearance is reduced to minimize leakage, while during throttle advances or climb conditions, the clearance is increased to prevent blade contact. This dynamic adjustment resolves the contradiction by making the clearance adaptive rather than fixed.
Solution Approach 2:
The control system continuously monitors engine operating parameters (thrust, rotor speed, flight conditions) and uses this feedback to adjust the tip clearance. Sensors detect conditions such as throttle advances or climb requests, and the controller responds by adjusting the clearance to maintain optimal values that prevent blade contact while minimizing leakage.
2Reliability
If the tip clearance is increased to prevent blade contact during throttle advances, then reliability is improved, but leakage over blade tips increases reducing engine efficiency
Solution Approach 1:
The system uses dynamic adjustment to change clearance based on operational phase. During cruise, minimal clearance reduces leakage; during throttle advances or climb conditions, clearance increases to prevent contact. This temporal separation of clearance values resolves the contradiction.
Solution Approach 2:
The system changes the clearance parameter in response to changing operational parameters (thrust, rotor speed, flight conditions). By monitoring these parameters and adjusting clearance accordingly, the system optimizes both reliability and efficiency for different operating regimes.
3Loss of energy
If active clearance control systems are used to maintain minimum clearance at cruise, then engine efficiency is improved, but the system cannot adapt effectively to varying operational conditions such as throttle advances
Solution Approach 1:
The control system incorporates continuous monitoring of engine parameters (thrust, rotor speed, flight conditions) and uses this feedback to detect operational changes such as throttle advances or climb requests. This feedback mechanism enables the system to adapt clearance settings to varying conditions while maintaining efficiency during cruise.
Solution Approach 2:
The system transitions from a static minimum clearance setting to a dynamic clearance control that responds to operational conditions. The clearance is adjusted in real-time based on detected conditions, making the system adaptable to different operational phases while maintaining optimal efficiency during cruise.
4Loss of energy
If the thrust limit is reduced to a de-rated maximum climb thrust during cruise, then optimal tip clearance can be maintained, but available thrust is reduced
Solution Approach 1:
The system dynamically adjusts the thrust limit based on operational conditions. During cruise, a de-rated thrust limit maintains optimal tip clearance and reduces fuel consumption. When climb conditions are detected, the thrust limit is increased to maximum climb thrust to provide adequate power. This dynamic adjustment resolves the contradiction between fuel efficiency and available power.
Solution Approach 2:
The system changes the thrust limit parameter in response to operational phase. By monitoring flight conditions and adjusting the thrust limit accordingly, the system optimizes both fuel efficiency during cruise and available power during climb, resolving the contradiction between these two performance parameters.
Data Source
AI summary
A system for controlling blade tip clearances in a gas turbine engine may comprise an active clearance control system and a controller in operable communication with the active clearance control system. The controller may be configured to identify a cruise condition, reduce a thrust limit of the gas turbine engine to a de-rated maximum climb thrust, determine a first target tip clearance based on the de-rated maximum climb thrust, and send a command signal correlating to the first target tip clearance to the active clearance control system.