Hydraulic Loop Architecture for Hydrogen Turbine Leak and Pressure Control

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Solution Overview

Problem

Challenges exist in managing cryogenic hydrogen temperatures and controlling actuators in hydrogen fuelled gas turbine engines, particularly in aircraft applications, where conventional systems are complex and pose safety risks due to hydrogen leaks and different material compatibility issues.

Innovation Solution

A closed-loop hydraulic system with a single hydrogen fuel heat exchanger and additional heat exchangers for engine fluids, along with a hydraulic pump that maintains higher pressure in the hydraulic system to prevent hydrogen leaks, and a high-pressure sub-loop for actuator control, reducing the risk of fires and system overpressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If multiple hydrogen-hydraulic heat exchangers are used to manage temperatures of hydrogen fuel and other engine fluids, then temperature management capability is improved, but system complexity and manufacturing difficulty increase due to multiple leak risk interfaces

Engineering Contradiction:
Improvetemperature management capabilityVSAvoidsystem complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent combines multiple heat exchange functions into a single hydrogen-hydraulic heat exchanger that simultaneously manages temperatures of hydrogen fuel and other engine fluids through integrated heat transfer pathways, eliminating the need for multiple separate exchangers and their associated leak risk interfaces

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single hydrogen-hydraulic heat exchanger is designed to perform multiple temperature management functions for different engine fluids including hydrogen fuel cooling and other engine fluid temperature control, making one component serve universal thermal management purposes

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If hydrogen fuel pressure is reduced in the heat exchanger, then safety against hydrogen leaks is improved, but hydraulic actuation capability deteriorates due to insufficient pressure for actuator operation

Engineering Contradiction:
Improvesafety against hydrogen leaksVSAvoidhydraulic actuation capability
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The hydraulic system is divided into two separate loops: a low-pressure hydrogen fuel loop that prioritizes safety with maximum 5 bar pressure, and a high-pressure hydraulic actuation loop that operates independently at higher pressures for effective actuator control, with each loop serving its specific function without pressure compromise

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A hydraulic pump acts as an intermediary device that draws low-pressure hydrogen-fuel-cooled hydraulic fluid and pressurizes it to high pressure for actuator operation, decoupling the pressure requirements of the hydrogen fuel system from the hydraulic actuation system while maintaining thermal management effectiveness

Inventive Principle:
Principle #24Intermediary (Mediator)

3Power

If hydraulic fluid pressure is maintained at high pressure throughout the system, then actuator performance is improved, but risk of component damage and system overpressure events increases

Engineering Contradiction:
Improveactuator performanceVSAvoidrisk of component damage
Core Design Contradiction:
PowerVSObject-affected harmful factors

Solution Approach 1:

The hydraulic system is segmented into a high-pressure sub-loop for actuators and a low-pressure main loop for cooling, with a restrictor creating a pressure barrier that protects downstream components from high pressure while maintaining actuator performance through selective high-pressure delivery

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

High pressure is applied locally only where needed for actuator operation through the high-pressure sub-loop, while other parts of the hydraulic system such as the heat exchanger and cooled components operate at lower pressures, providing pressure-appropriate conditions for each component

Inventive Principle:
Principle #3Local quality

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 effectively manages fluid temperatures and actuator control, offering safety, weight, and cost advantages by minimizing hydrogen leaks and reducing component damage, while supporting dual or triple-fuel architectures without active actuation.

Implementation Method 1

a first heat exchanger configured to exchange heat between hydrogen fuel and hydraulic fluid within the hydraulic fluid conduit

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

a further heat exchanger configured to exchange heat between the hydraulic fluid and one or more further engine fluids

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

a hydraulic pump configured to pressurise and drive hydraulic fluid flow through the hydraulic fluid conduit

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP4636237B1Gas turbine engine hydraulic system
Publication Date: 2026.04.15 ROLLS ROYCE PLC
  • EP4636237B1 patent drawingFigure 1
  • EP4636237B1 patent drawingFigure 2
  • EP4636237B1 patent drawingFigure 3

AI summary

A hydraulic system for a hydrogen fuelled gas turbine engine. The hydraulic system comprises a closed-loop hydraulic fluid conduit (232), a hydrogen-hydraulic fluid heat exchanger (230) configured to exchange heat between cryogenic hydrogen fuel and hydraulic fluid within the hydraulic fluid conduit (232), and a second fuel-hydraulic heat exchanger (518) configured to exchange heat between a second, non-hydrogen fuel and hydraulic fluid in the hydraulic fluid conduit (232).