Turbine Engine Speed Transient Control via Adaptive Fuel Trajectory

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Solution Overview

Problem

Existing gas turbine engine control systems face challenges in achieving reproducible acceleration and deceleration times due to inertia and varying engine conditions, leading to thrust asymmetry and non-reproducibility between engines.

Innovation Solution

Implementing a speed transient regulation loop that detects intended speed transients and adjusts fuel-flow-rate setpoints based on a speed trajectory, using a combination of steady speed and speed transient regulation loops to ensure consistent acceleration and deceleration times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a steady speed regulation loop with C/P stop is used to protect against pumping during speed changes, then engine reliability is improved, but acceleration and deceleration time increase and become non-reproducible

Engineering Contradiction:

Improveprotection against pumpingVSAvoidacceleration and deceleration time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the regulation loop adaptive - it transitions from a static C/P stop approach to a dynamic trajectory-based approach that adjusts fuel injection rates according to the engine's actual speed trajectory, allowing optimization of both protection and performance over time

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the control parameter from a fixed maximum rate limit to a time-varying trajectory that specifies the desired speed path, enabling the system to achieve reproducible acceleration and deceleration times while maintaining protection against pumping through appropriate trajectory design

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a regulation loop with fixed maximum fuel injection rate is used, then protection against pumping is improved, but conformity between engines of the same type deteriorates

Engineering Contradiction:

Improveprotection against pumpingVSAvoidconformity between engines

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent transforms the fixed parameter approach into a time-varying parameter approach, where the fuel injection rate follows a predetermined trajectory that ensures consistent acceleration and deceleration characteristics across engines of the same type, improving conformity while maintaining protection

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If a lowest win type gate is used to select fuel-flow-rate setpoint, then simplicity is improved, but acceleration reproducibility deteriorates due to premature selection of main loop

Engineering Contradiction:

Improveselection logic simplicityVSAvoidacceleration time reproducibility

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent introduces feedback by continuously monitoring the actual speed trajectory and comparing it with the desired trajectory, using this information to adjust fuel injection rates and maintain reproducible acceleration times, overcoming the limitations of simple selection logic

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9206746B2Method of controlling speed transients in a turbine engine

Publication Date: 2015.12.08 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A method of controlling an engine in which a fuel flow setpoint is determined is provided. The method includes implementing a steady speed regulation loop in which the fuel-flow-rate setpoint is determined as a function of a difference between a setpoint parameter that depends on the position of a control lever and an operating parameter of the engine; detecting an intended speed transient; and implementing a speed transient regulation loop in which the fuel-flow-rate setpoint is determined as a function of a difference between a speed of the engine and a speed setpoint varying over time with the speed trajectory as generated in predetermined manner, if a speed transient is detected.