Liquid Hydrogen Fuel Pumping With Compressed-Air Turbine Drive
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Solution Overview
Problem
Existing gas turbine engines face challenges in pumping liquid hydrogen fuel due to its low temperature and low lubricity, requiring high rotational speeds that traditional drives and gears cannot accommodate, and existing systems are inefficient for varying fuel demand during different operating conditions.
Innovation Solution
A fuel system that uses compressed air flow to drive a driving turbine, which in turn powers a fuel pump, eliminating the need for traditional drives and gears, and incorporates a transmission system with epicyclic gearboxes to manage power transfer and adjust fuel flow based on operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional low-pressure centrifugal pumps and high-pressure gear pumps are used to pump liquid hydrogen, then the pumping system can operate at lower rotational speeds, but the pumps cannot achieve sufficient pumping capacity for liquid hydrogen due to its low temperature (25K) and low lubricity
Solution Approach 1:
The patent replaces traditional mechanical pump drives (electric motors, gearboxes) with a turbine-driven system. The turbine converts thermal energy from hot compressed air directly into mechanical rotation, eliminating the need for electrical drives and gearboxes. This substitution enables the fuel pump to achieve the high rotational speeds (typically 100,000 RPM) necessary for liquid hydrogen pumping without the complexity of traditional drive systems.
Solution Approach 2:
The patent changes the operating parameters of the fuel pump by using a turbine drive system that can achieve much higher rotational speeds than traditional electric motors or gearboxes. The turbine is powered by hot compressed air from the gas turbine engine, allowing the pump to operate at the high speeds required for liquid hydrogen while maintaining adequate lubrication through the unique properties of liquid hydrogen at these speeds.
2Productivity
If high-speed turbo pumps driven by fuel-burning turbines are used to pump liquid hydrogen, then sufficient pumping capacity is achieved, but the system complexity increases and fuel is consumed to drive the pump
Solution Approach 1:
The patent makes the compressed air system serve multiple functions: it provides breathable air for the cabin, powers the cabin blower for de-icing, and drives the turbine that powers the fuel pump. By utilizing the existing compressed air from the gas turbine engine's compressor, the system eliminates the need for a separate fuel-burning turbine, reducing overall system complexity and eliminating fuel consumption for pump operation.
Solution Approach 2:
The system uses its own compressed air output to power its own fuel pump through the turbine. The compressed air generated by the gas turbine engine's compressor is diverted to drive the turbine, which in turn drives the fuel pump. This self-service approach eliminates the need for external fuel-burning turbines or electric motors, simplifying the overall system architecture.
3Device complexity
If compressed air is used to drive a turbine that powers the fuel pump, then fuel consumption is eliminated and system complexity is reduced, but the ability to vary fuel flow to match varying demand during different operating conditions is limited
Solution Approach 1:
The patent incorporates a continuously variable transmission (CVT) in the drive path between the turbine and the fuel pump. The CVT allows the pump speed to be varied continuously to match fuel demand during different operating conditions. This dynamic adjustment capability enables the system to adapt fuel flow to varying conditions while maintaining the simplified turbine-driven architecture without fuel-burning turbines or complex electrical drive systems.
4Speed
If traditional electric drives and gearboxes are used to power the fuel pump, then speed control is easier, but the system becomes too complex and cannot achieve the high rotational speeds necessary for liquid hydrogen pumping
Solution Approach 1:
The patent replaces traditional mechanical pump drives (electric motors, gearboxes) with a turbine-driven system. The turbine converts thermal energy from hot compressed air directly into mechanical rotation, eliminating the need for electrical drives and gearboxes. This substitution enables the fuel pump to achieve the high rotational speeds (typically 100,000 RPM) necessary for liquid hydrogen pumping without the complexity of traditional drive systems.
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 high-speed pumping of liquid hydrogen without traditional drives or gears, efficiently managing fuel flow across varying conditions, and supports engine startup without burning fuel.
Implementation Method 1
A driving turbine is provided upstream of the fuel line to drive the fuel pump
Implementation Method 2
The fuel pump is a low pressure centrifugal pump
Data Source
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AI summary
Disclosed is a fuel system for a gas turbine engine. The system comprises a fuel pump for fluid communication with a fuel reservoir; a driving turbine for driving the fuel pump; and a source of compressed air flow to drive the driving turbine. The source of compressed air may be the engine core, a dedicated fuel system compressor or the compressor of a cabin blower system.