Predictive Rotor Tip Clearance Control for Gas Turbine Transients
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Solution Overview
Problem
Existing methods for controlling rotor tip clearance in gas turbine engines rely on current conditions and measurements, leading to a time lag between measurement and control action, which can result in rotor tip rub during rapid transient changes, such as step climbs or auto-throttle maneuvers, as the clearance can reduce to zero before control action occurs.
Innovation Solution
A method that measures engine parameters to determine engine power demand, calculates rotor tip clearance, and controls the clearance based on the difference between the calculated clearance and a predefined target clearance, allowing for earlier intervention and reducing the incidence of rotor tip rub.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If control action is taken based on current clearance measurements, then control accuracy is improved, but response time is delayed causing rotor tip rub during rapid transients
Solution Approach 1:
The control system performs preliminary action by predicting future clearance values based on current engine parameters and rate of change data, then takes control action based on these predictions rather than waiting for actual clearance measurements. This allows the control system to act before the clearance actually reaches critical levels during rapid transients, eliminating the time lag problem while maintaining control accuracy.
2Manufacturing precision
If control action is delayed until clearance measurement is complete, then control precision is maintained, but rotor blade and casing life is reduced due to tip rub
Solution Approach 1:
The system calculates predicted clearance values in advance using current engine parameters and their rates of change, enabling control action to be taken before tip rub occurs. This preliminary prediction and action prevents damage to rotor blades and casing while maintaining precise clearance control through the prediction algorithm.
3Loss of energy
If active clearance control is implemented during rapid transient changes, then engine efficiency is improved, but control reliability decreases due to insufficient response time
Solution Approach 1:
By predicting future clearance values based on current parameters and their rates of change, the system can proactively adjust clearance during rapid transients before critical conditions occur. This preliminary prediction capability ensures reliable control action even during fast-changing operating conditions, maintaining both engine efficiency and control reliability.
Data Source
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AI summary
A method of controlling a rotor tip clearance arrangement of a gas turbine engine and a control system configured to control rotor tip clearance. Steps include measuring at least one engine parameter; determining engine power demand from the at least one engine parameter; and calculating rotor tip clearance given the determined engine power demand. The rotor tip clearance arrangement is controlled to increase or decrease the rotor tip clearance based on the difference between the calculated clearance and a predefined target clearance. Corresponding control system for controlling a rotor tip clearance arrangement.