Hydraulic Engine Motoring via Fuel Pump and Selector Valve
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Solution Overview
Problem
Existing engine motoring systems rely on air turbine starters, which may not effectively equalize radial temperatures in engine cores, especially when engines are stationary after high-temperature operation.
Innovation Solution
A system utilizing an electrically driven fuel pump and a selector valve to drive a high pressure spool of a dual spool engine at different speeds, allowing for hydraulic rotation without the air turbine starter, and incorporating a fuel metering system and recirculating fuel line for efficient fuel management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an air turbine starter is used to motor the engine, then the engine can be rotated to equalize radial temperatures, but the system complexity increases and the engine cannot be effectively cooled when stationary
Solution Approach 1:
The fuel pump is designed to perform multiple functions: normally it supplies fuel to the combustor for combustion, but when the selector valve switches to the second position, it drives the hydraulic rotation unit to rotate the high pressure spool for temperature equalization. This eliminates the need for a separate air turbine starter while achieving the same cooling effect.
Solution Approach 2:
The invention uses hydraulic principles by directing pressurized fuel through a hydraulic rotation unit (motor) that converts hydraulic energy into mechanical rotation. The selector valve controls fuel flow to either the combustor or the hydraulic rotation unit, enabling the fuel system to serve dual purposes: power generation and engine rotation for cooling.
2Speed
If the air turbine starter is used for engine motoring, then rotation can be achieved, but the system requires additional components and cannot be controlled based on engine state
Solution Approach 1:
The fuel pump serves dual purposes: fuel supply during normal operation and hydraulic power source for rotation during cooling. The selector valve enables switching between these modes based on engine state, eliminating the need for a separate air turbine starter and its associated complexity.
Solution Approach 2:
The controller monitors engine state parameters and automatically controls the selector valve to switch between fuel supply mode and hydraulic rotation mode. This feedback-based control ensures the engine is rotated for temperature equalization only when needed, based on actual engine conditions.
3Power
If fuel is supplied directly to the combustor, then combustion can occur, but the engine cannot be rotated when stationary after high temperature operation
Solution Approach 1:
The system dynamically switches between two operational modes based on real-time engine conditions. During normal operation, fuel flows to the combustor for power generation. When the engine is stationary after high-temperature operation, the selector valve switches to direct fuel to the hydraulic rotation unit, enabling the fuel system to adapt its function to current operational needs.
Solution Approach 2:
The fuel system is designed to perform both combustion power generation and hydraulic-driven rotation. The selector valve enables the system to switch between these two functions based on whether the engine needs power or temperature equalization, making the fuel system universally applicable to both purposes.
Data Source
AI summary
In accordance with at least one aspect of this disclosure, a system includes a fuel line, an electrically driven fuel pump configured to supply fuel to a first fuel line branch and a second fuel line branch, and a selector valve disposed in the fuel line at a juncture of a first fuel line branch and a second fuel line branch configured to communicate the electrically driven fuel pump with the first fuel line branch or the second fuel line branch based on a position of the selector valve. In a first position, the selector valve is configured to fluidly connect the electrically driven fuel pump with the first fuel line branch to supply fuel to a combustor of the engine and drive a high pressure shaft at a first speed. In a second position, the selector valve is configured to fluidly connect the electrically driven fuel pump with the second fuel line branch to drive a hydraulic rotation unit configured to drive the high pressure spool of the engine at a second speed different from the first speed.