Aircraft Engine Thrust Control via Nozzle Scheduling
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Solution Overview
Problem
Existing gas turbine engine control systems fail to optimize all available effectors to achieve performance and operability goals, and do not fully utilize engine characteristics and dynamic models to optimize engine performance in real-time while protecting engine state limits.
Innovation Solution
A control system that includes a nozzle scheduler, system sensors, an engine model, and a control module to determine control commands for fuel flow and exhaust nozzle positions based on flight conditions, using off-line simulations and real-time sensor signals to optimize thrust control, with a hybrid model predictive control module for real-time optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If prior engine control systems use transient schedules developed off-line to optimize fuel consumption, then fuel consumption is reduced, but the system cannot optimize all available effectors to achieve performance and operability goals in real-time
Solution Approach 1:
The patent uses off-line simulations to pre-determine optimal transient schedules for exhaust nozzle positions across various flight conditions. These pre-calculated schedules are stored and then referenced in real-time operation, allowing the system to achieve optimized fuel consumption without requiring complex real-time computation for each decision.
Solution Approach 2:
The control system continuously monitors actual engine parameters (such as thrust, temperature, and pressure) and compares them against the desired targets from the transient schedules. Based on this feedback, the system adjusts fuel flow and exhaust nozzle positions to minimize deviations while optimizing fuel consumption in real-time.
2Reliability
If engine control systems use off-line simulations and tests to develop transient schedules, then performance goals are achieved, but the system does not fully utilize engine characteristics and dynamic models for real-time optimization
Solution Approach 1:
Comprehensive off-line simulations and tests are performed beforehand to develop detailed transient schedules that incorporate engine characteristics and dynamic models. These pre-computed optimal trajectories are stored for various flight conditions, enabling reliable performance goal achievement without requiring heavy real-time computation.
Solution Approach 2:
The control system dynamically selects and adapts pre-computed transient schedules based on current flight conditions (such as altitude, Mach number, and throttle position). The system can also dynamically adjust parameters within the scheduled trajectories to account for real-time variations in engine state and environmental conditions, maintaining optimal performance without sacrificing reliability.
3Use of energy by moving object
If control systems manage competing operability and performance objectives by resetting engine exhaust nozzles using transient schedules, then fuel consumption is minimized, but the system does not optimize all available effectors
Solution Approach 1:
The control system merges the control of multiple effectors (fuel flow, exhaust nozzle position, and potentially other variables) into a unified transient schedule framework. By coordinating these effectors together based on pre-computed optimal trajectories, the system achieves fuel consumption minimization while managing the complexity of multi-effector interaction through integrated control logic.
Data Source
AI summary
A control system for a gas turbine engine, a method for controlling a gas turbine engine, and a gas turbine engine are disclosed. The control system may include a nozzle scheduler for determining an exhaust nozzle position goal based on a nozzle schedule of exhaust nozzle positions related to flight conditions. The control system may further include a control module for determining a control command for the gas turbine engine. The control command may include, at least, a fuel flow command and an exhaust nozzle position command and the control command may be based on, at least, the exhaust nozzle position goal and an estimated thrust value. The control system may further include an actuator for controlling the gas turbine engine based on the control command.