Aircraft Fuel Nozzle Thermal Growth Compensation

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Solution Overview

Problem

Conventional aircraft fuel nozzles experience heat transfer issues that lead to fuel breakdown and coking deposition, restricting fuel flow, and traditional solutions like heat shields increase weight, which is disadvantageous in aircraft design.

Innovation Solution

A unique fuel nozzle design that transports bulk fuel flow downstream within the nozzle, minimizing surface area exposed to heat transfer and incorporating a coiled section to compensate for thermal growth mismatches, reducing heat pick-up and weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If heat shields or long thermal paths are used to manage thermal energy transfer, then fuel temperature control is improved, but nozzle weight increases

Engineering Contradiction:

Improvefuel temperatureVSAvoidnozzle weight

Core Design Contradiction:

TemperatureVSWeight of moving object

Solution Approach 1:

The fuel nozzle is divided into multiple functional sections: an upstream bulk fuel flow section that transports fuel downstream, and a downstream section where fuel is split into multiple flow passages. This segmentation allows the bulk transport function to be separated from the distribution function, enabling reduced surface area exposure to heat transfer in the bulk flow section while maintaining effective fuel distribution downstream.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fuel flow path transitions from a conventional two-dimensional planar path to a three-dimensional configuration by extending the bulk fuel flow section downstream before splitting. This dimensional extension increases the axial length of the bulk flow path, reducing the surface area to volume ratio and minimizing heat transfer exposure without adding significant weight.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of operation

If conventional fuel flow paths are used, then fuel distribution is achieved, but heat transfer causes fuel breakdown and coking

Engineering Contradiction:

Improvefuel distributionVSAvoidheat transfer

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The fuel is transported through the bulk flow section downstream before being split into multiple passages. This preliminary action of extending the bulk flow path reduces the surface area to volume ratio, minimizing heat transfer exposure and preventing fuel breakdown and coking before the fuel reaches the distribution section.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Different sections of the fuel nozzle are designed with different flow characteristics: the upstream section maintains bulk flow with minimal surface area exposure to reduce heat transfer, while the downstream section provides distributed flow through multiple passages for effective fuel distribution. This local differentiation optimizes both heat transfer resistance and fuel distribution performance.

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 design achieves lower fuel temperatures, reduces coking, and minimizes thermal stresses while maintaining efficient fuel distribution and spray performance, thus enhancing the operational efficiency and lifespan of gas turbine engines.

Implementation Method 1

heat transfer from the ambient environment to the fuel passing through the nozzle

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

transferring the thermal energy through intentionally long thermal paths

Methodology Applied

Scientific EffectThermal energy transfer: Conduction (thermal)

Implementation Method 3

thermal growth mismatches in different regions of the fuel flow path

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 4

one or more spray nozzles connected to the other end of the stem for directing the fuel into the combustion chambers

Methodology Applied

Scientific EffectSpray: Spray

Data Source

PatentUS20220099290A1Aircraft fuel nozzle

Publication Date: 2022.03.31 PARKER HANNIFIN CORP

AI summary

A fuel injector for an aircraft gas turbine engine includes a housing stem, a fuel nozzle coupled to the housing stem, and a fuel conduit extending through the housing stem and into the fuel nozzle where the fuel conduit bends to extend in a longitudinal downstream direction within the fuel nozzle. The fuel conduit is configured to transport bulk fuel flow further along the nozzle before being split downstream in the fuel circuit for final spray distribution, thereby promoting lower fuel temperatures. The fuel nozzle may minimize metal-to-metal contact between an external wall of the nozzle in thermal communication with ambient environment and an internal portion of the nozzle in thermal communication with the fuel circuit to minimize heat pick-up in the fuel. The fuel conduit may include a coiled section within a cavity of the fuel nozzle for compensating for thermal growth mismatches of the fuel injector.