Aircraft Liquid Hydrogen Fuel Recirculation for Cavitation Control
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Solution Overview
Problem
Conventional liquid hydrogen fuel pumps have low life capability due to cavitation erosion and are heavy, making them difficult to incorporate into aircraft propulsion systems, especially with the varying fuel flow rates required for aviation applications.
Innovation Solution
A fuel system design incorporating a jet pump, primary pump, and heat exchanger within a hydrogen fuel tank, with a recirculation path that cools and pressurizes fuel, reducing cavitation and system weight by integrating tank pressurization and recirculation systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional liquid hydrogen fuel pumps are used, then fuel can be delivered to the propulsion system, but the pumps suffer from cavitation erosion and have low life capability
Solution Approach 1:
The system pre-cools the hydrogen fuel before it enters the jet pump through a heat exchanger, and pre-pressurizes it using a pressurization system. This preliminary conditioning of the fuel ensures that it enters the pump at optimal temperature and pressure, preventing cavitation erosion and extending pump life
Solution Approach 2:
The patent implements a feedback mechanism where a portion of the cooled fuel is recirculated back to the heat exchanger inlet. This feedback loop maintains consistent fuel temperature and pressure conditions, stabilizing the pump operating conditions and preventing cavitation
2Weight of moving object
If conventional hydrogen fuel systems are used, then fuel can be stored and delivered, but the systems are heavy and difficult to incorporate into aircrafts
Solution Approach 1:
The patent merges multiple functions into integrated components. The heat exchanger serves both as a cooling device and as a structural element within the fuel tank. The jet pump is positioned to utilize the tank's geometry. This consolidation reduces the number of separate components and reduces overall system weight
Solution Approach 2:
The heat exchanger is nested within the hydrogen fuel tank structure, and the jet pump is positioned within the tank geometry. This nesting arrangement eliminates the need for separate external cooling systems and reduces the overall footprint and weight of the fuel system
3Adaptability or versatility
If conventional fuel systems are used, then fuel can be delivered to the propulsion system, but the systems are complicated by the wider range of propulsion fuel flow rates required for aviation applications
Solution Approach 1:
The patent employs dynamic control elements including adjustable flow control valves and variable speed pumps that can adapt to varying fuel flow rate requirements. The recirculation system dynamically adjusts fuel flow based on propulsion system demands, enabling the system to handle the wider range of fuel flow rates required for aviation applications without increasing structural complexity
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
The system enhances the life cycle of primary pumps, reduces size and weight, and improves efficiency by minimizing cavitation and pressure fluctuations, making it suitable for aerospace applications.
Implementation Method 1
The heat exchanger is configured to transfer heat from the fuel of the first recirculation path to the fuel tank and the first fuel recirculation path directly supplies the cooled fuel to a first inlet of the jet pump
Implementation Method 2
a jet pump within the hydrogen fuel tank, at least one primary pump receiving fuel from the jet pump and pressurizing fuel to an outlet path
Data Source
AI summary
A fuel system having a hydrogen fuel tank for fueling a fuel feed and propulsion system. The fuel system having a jet pump within the hydrogen fuel tank, at least one primary pump receiving fuel from the jet pump and pressurizing fuel to an outlet path and a first fuel recirculation path configured to selectively recirculate fuel to the hydrogen fuel tank. The first fuel recirculation path is fluidly connected to the outlet path. The first fuel recirculation path includes a heat exchanger positioned within the hydrogen fuel tank to cool fuel received from at least one of the fuel feed system or a tank pressurization system. The heat exchanger and a Joule-Thomson expansion at the jet pump minimizes recirculated fuel temperature, which in combination with a selective flow recirculation rate improve the life of the primary pump downstream.