Hydrogen Combustor Layout With Downstream Air Mixing

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Solution Overview

Problem

The use of hydrogen as a fuel in gas turbine engines poses challenges due to its gaseous state and increased flammability, which can lead to burn back issues if ignition occurs too close to the fuel feed.

Innovation Solution

A combustor design with central fuel injection and radially outer air injection, where fuel and air are mixed downstream to reduce the risk of flame propagation, utilizing hydrogen as the fuel source.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If hydrogen is used as fuel in gas turbine engines, then energy efficiency and environmental performance are improved, but the risk of burn back increases due to hydrogen's gaseous state and increased flammability

Engineering Contradiction:

Improveenergy efficiencyVSAvoidburn back risk

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by introducing air through outer air supply slots before the fuel injection point, creating a pre-mixing zone where air is already present downstream of the fuel outlet. This preliminary air supply establishes a controlled mixing environment that prevents flame propagation back to the fuel feed, thereby reducing burn back risk while maintaining hydrogen's energy efficiency benefits

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses an intermediary approach by creating a separate air supply system (outer air slots) that acts as a mediator between the fuel injection and combustion chamber. This intermediary air supply controls the mixing process and flame front propagation, preventing direct flame contact with the fuel feed while allowing complete combustion of hydrogen to maintain energy efficiency

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If fuel and air are mixed immediately at the injection point, then combustion efficiency is improved, but flame propagation back to the fuel feed increases

Engineering Contradiction:

Improvecombustion efficiencyVSAvoidflame propagation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies segmentation by separating the fuel injection function from the air mixing function in the axial direction. Fuel is injected at one axial position while air is supplied at a different axial position (downstream), creating distinct zones for fuel delivery and air mixing. This segmentation prevents immediate mixing at the injection point, reducing flame propagation risk while maintaining combustion efficiency through controlled downstream mixing

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses dimensional separation by arranging fuel and air supplies at different axial positions along the combustor length. This axial dimensionality change creates a spatial separation between fuel injection and air mixing, allowing combustion to occur efficiently in a downstream zone while preventing flame propagation back to the fuel feed at the upstream injection point

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 design effectively reduces the risk of burn back by ensuring adequate mixing and separation of fuel and air, maintaining safety and efficiency in hydrogen-fueled gas turbine engines.

Implementation Method 1

A combustor for a gas turbine engine... with central fuel injection and radially outer air injection

Methodology Applied

Scientific EffectCentral fuel injection:

Implementation Method 2

An inner air supply is radially outward of the central fuel passage to deliver air into inner slots extending downstream

Methodology Applied

Scientific EffectRadial air injection:

Implementation Method 3

An outer air supply is radially outward of the inner air supply to deliver air into an outer slot extending downstream

Methodology Applied

Scientific EffectOuter air injection:

Implementation Method 4

fuel and air are mixed downstream to reduce the risk of flame propagation

Methodology Applied

Scientific EffectDownstream mixing:

Data Source

PatentEP4411242B1Combustor with central fuel injection and downstream air mixing

Publication Date: 2026.04.01 PRATT & WHITNEY CANADA CORP

Figure 1
Figure 2A~2C

AI summary

A combustor (100) has a mixing body (104) with a central fuel passage (106) with a central axis (108) and is adapted to be connected to a source of fuel. A nose (110) at a forward end (113) includes a plurality of fuel injection passages (114) allowing fuel to flow from the central fuel passage (106) into an area (112) forward of an outlet (115) from the fuel injection passages (114). An inner air supply radially outwardly of the central fuel passage (106) delivers air into inner slots (120) extending downstream of outlets (115) of the fuel injection passages (114) such that air and fuel can begin to be mixed and move downstream of an end (113) of the nose (110). An outer air supply delivers air downstream of the inner air outlet (115) such that air from the outer air supply, air from the inner slots (120) and fuel from the fuel injection passages (114) are all driven forwardly into a combustion chamber (105). A gas turbine engine (20) is also disclosed.