Gas Turbine Fuel Shutoff Control for Fail-Down and Fail-Fixed Modes
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Solution Overview
Problem
Conventional fuel control systems for gas turbine engines require different physical forms and interfaces for fail-down and fail-fixed applications, necessitating complex adapters and modifications, and lack a common design for both configurations.
Innovation Solution
A fuel control system with a first stage unit that can be configured for either fail-down or fail-fixed applications, using a proportional device or latching device to manage fuel flow, allowing a common hydraulic and mechanical interface and a single housing design for both modes, and incorporating a rotary valve with a stepper motor for precise fuel metering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fuel control systems are designed for fail-down application, then fuel supply decreases upon loss of electrical power, but the system requires substantially different physical forms and interfaces compared to fail-fixed application
Solution Approach 1:
The shutoff effector is designed with a common physical form and interface that can be configured for both fail-down and fail-fixed applications through software or control logic, eliminating the need for different hardware designs. The first stage unit and second stage unit work together to provide different fail modes using the same mechanical structure, thereby reducing device complexity while maintaining reliability.
Solution Approach 2:
The system uses a dynamic configuration approach where the shutoff effector can switch between fail-down and fail-fixed modes through the control system. The first stage unit receives electrical power and controls the second stage unit to achieve different outcomes (decrease fuel supply or maintain fuel supply) based on the selected fail mode, allowing adaptability without changing physical forms.
2Reliability
If conventional fuel control systems are designed for fail-fixed application, then fuel supply is continuously maintained upon loss of electrical power, but the system requires substantially different physical forms and interfaces compared to fail-down application
Solution Approach 1:
The shutoff effector employs a universal design with common physical forms and interfaces that supports both fail-fixed and fail-down configurations. The same first stage unit and second stage unit structure can be programmed or configured to maintain fuel supply (fail-fixed) or decrease fuel supply (fail-down) upon electrical power loss, eliminating the need for different hardware implementations.
Solution Approach 2:
The system achieves dynamic adaptability where the shutoff effector can operate in different fail modes using the same physical components. The control system configures the first stage unit to either maintain or decrease fuel supply based on the selected fail mode, allowing the system to switch between fail-fixed and fail-down behavior without requiring different physical forms or interfaces.
3Reliability
If different physical forms and interfaces are used for fail-down and fail-fixed applications, then each application can be optimized, but complex adapters and complicated modifications are required to switch between configurations
Solution Approach 1:
The shutoff effector is designed as a universal component with a common physical form and interface that can be configured for different applications through software or control logic settings. This eliminates the need for complex adapters and modifications when switching between fail-down and fail-fixed configurations, as the same hardware platform supports both modes natively.
Solution Approach 2:
The system uses dynamic configuration capabilities to switch between fail-down and fail-fixed modes without requiring physical modifications or adapters. The first stage unit and second stage unit can be reconfigured through control signals to optimize for different applications, making the system adaptable and easy to manufacture in a single standardized design.
4Device complexity
If a common design is used for both fail-down and fail-fixed configurations, then device complexity is reduced, but the system must accommodate different failure modes with the same components
Solution Approach 1:
The shutoff effector achieves adaptability through dynamic control configuration rather than physical variation. The first stage unit receives electrical power and controls the second stage unit to produce different outcomes (fuel supply decrease or maintenance) based on the selected fail mode. This dynamic reconfigurability allows a common design to accommodate both fail-down and fail-fixed configurations with full versatility.
Solution Approach 2:
The unified design of the shutoff effector incorporates multi-functionality, allowing the same first stage unit and second stage unit to serve both fail-down and fail-fixed applications. The system uses control logic or software configuration to enable the common hardware to adapt to different failure modes, maintaining both low device complexity and high adaptability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables rapid shutdown or continuous fuel supply during electrical power loss, preventing engine overspeed and thrust perturbation, while maintaining a unified design and reducing complexity and mass.
Implementation Method 1
incorporating a rotary valve with a stepper motor for precise fuel metering
Implementation Method 2
using a proportional device or latching device to manage fuel flow
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A fuel control system (100) for a gas turbine engine (10) includes a fuel metering valve (140), a pressure raising and shut-off valve (PRSOV) (160), and a shutoff effector (200) including a first stage unit (210) that is electrically powered and a second stage unit (250) that is controlled by the first stage unit (210). The second stage unit (250) actuates a valve member (162) of the PRSOV (160) between an open position (162A) that allows supply of a fuel to burners of the gas turbine engine (10) and a closed position (162B) that prevents supply of the fuel to the burners. Upon loss of electrical power to the first stage unit (210) during operation of the gas turbine engine (10), the first stage unit (210) is configured to: control the second stage unit (250) to actuate the valve member (162) of the PRSOV (160) to the closed position (162B) after a predetermined time duration (T1); or retain the valve member (162) of the PRSOV (160) in the open position (162A).