Gas Turbine Rotor Speed Keep Out Zone Control
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Solution Overview
Problem
Gas turbine engines experience increased wear in certain speed ranges, leading to reduced engine component life, as the high spool speed 'floats' relative to the low spool speed, making it difficult to control and maintain optimal operating conditions.
Innovation Solution
A model-based rotor speed control system that determines closing and opening thresholds for a high pressure compressor stator vane actuator to maintain the high spool speed within a defined keep out zone, using an on-board model to apply corrections and prevent excessive wear by controlling the position of high pressure compressor stator vanes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the high spool speed is allowed to float relative to the low spool speed, then the engine operation is simple and responsive to fuel consumption changes, but the engine components experience increased wear due to dwelling in speed ranges that exacerbate wear
Solution Approach 1:
The control system continuously monitors the high spool speed and compares it against defined keep-out zones. When the speed enters a harmful range, the system automatically applies corrections to the effector (such as compressor stator vanes or fuel control) to push the speed back outside the harmful range, creating a closed-loop feedback mechanism that prevents wear-exacerbating conditions
Solution Approach 2:
The control system proactively detects when the high spool speed is approaching harmful speed ranges and applies corrections before the engine operates in those conditions. By using on-board models to predict future states, the system takes preliminary action to prevent entry into keep-out zones rather than reacting after damage occurs
2Reliability
If model-based control corrections are applied to prevent dwelling in wear-exacerbating speed ranges, then component life is extended, but the control system complexity increases
Solution Approach 1:
The control system uses the engine's own operational data and on-board models to automatically determine and apply corrections without external intervention. The system self-regulates by monitoring its own state, predicting future conditions, and autonomously adjusting effectors to maintain operation outside harmful speed ranges
Solution Approach 2:
The control system dynamically adjusts operational parameters (such as effector position or fuel flow) based on the current high spool speed and predicted trajectory. By changing these parameters in real-time, the system can steer the engine operation away from harmful speed ranges while maintaining overall system functionality
Data Source
AI summary
A system includes a gas turbine engine and a controller operable to determine a closing threshold with respect to an upper limit and an opening threshold with respect to a lower limit of a movement range of an effector of the gas turbine engine based on an on-board model, where the upper limit and the lower limit are defined for a target parameter of the gas turbine engine. The controller determines a projected state of the target parameter absent a correction command to the effector, applies a closing correction to the effector based on determining that the projected state of the target parameter would result in being above the closing threshold, and applies an opening correction to the effector based on determining that the projected state of the target parameter would result in being below the opening threshold.