Gas Turbine Surge Margin Control for Shaft Break Safety

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Solution Overview

Problem

Gas turbine engines face challenges in quickly and safely dissipating energy in the event of a shaft break, which can lead to catastrophic failure and debris release due to the rapid acceleration of turbines, necessitating a control system to increase the likelihood of surge and prevent recovery from surge.

Innovation Solution

A gas turbine engine control system that generates an arm signal to alter the variable stator vane schedule and limit the response rate of the variable stator vane actuator, reducing the surge margin and preventing recovery from surge, thereby promoting energy dissipation through engine surge in the event of a shaft break.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the variable stator vane schedule is altered to slew each variable stator vane to decrease the available surge margin, then the likelihood of engine surge increases and energy is dissipated, but the risk of catastrophic failure from rapid turbine acceleration increases

Engineering Contradiction:

Improvesurge marginVSAvoidenergy dissipation risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The control system performs preliminary action by detecting shaft break conditions and preemptively altering the variable stator vane schedule to induce surge before catastrophic failure occurs. This提前 action transforms the operational state to safely dissipate energy that would otherwise cause damage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control system converts the harmful effect of rapid energy release from shaft break into a beneficial controlled surge event. By inducing surge through vane scheduling, the system channels destructive energy into a controlled compression system instability that safely dissipates energy without catastrophic consequences.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If the variable stator vane actuator response rate is limited, then recovery from surge is prevented, but the response time to induce surge decreases

Engineering Contradiction:

Improvesurge recovery preventionVSAvoidactuator response rate

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The control system applies dynamic control by adjusting the variable stator vane schedule in real-time in response to detected shaft break conditions. The actuator response rate is dynamically limited to prevent recovery, ensuring the system remains in the surge state for safe energy dissipation rather than returning to unstable operation.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If the variable stator vanes are slewed by a fixed angle, then the control system is simple to implement, but the adaptability to different engine power and environmental conditions is reduced

Engineering Contradiction:

Improvecontrol system complexityVSAvoidoperational condition adaptability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The control system changes operational parameters by adjusting the variable stator vane angle based on engine power level and environmental conditions. Rather than using a fixed slew angle, the system modifies the vane schedule parameters adaptively to optimize surge induction across different operating scenarios while maintaining manageable complexity.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9341076B2Surge margin control

Publication Date: 2016.05.17 ROLLS ROYCE PLC

AI summary

A gas turbine engine control system comprising a variable stator vane schedule for normal operation of the gas turbine engine. The system is configured to generate an arm signal indicating potential shaft break. Then the system is configured to alter the variable stator vane schedule to slew each variable stator vane to decrease the available surge margin in response to the arm signal. Or the system is configured to limit a response rate of a variable stator vane actuator in response to the arm signal. Or the system is configured to alter the variable stator vane schedule and limit the response rate of the actuator.