Feed Arm for Multiple Circuit Fuel Injector

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional multiple circuit fuel injectors for gas turbine engines face issues with coking in both primary and secondary fuel flow passages due to extreme heat, leading to fuel deposition and flow restrictions, especially in the secondary passage where fuel velocity is low or intermittent.

Innovation Solution

A feed arm design for a multiple circuit fuel injector featuring an elongated tubular sleeve and fuel tube with a primary fuel flow passage that surrounds the secondary passage, facilitating heat transfer through conduction and convection, and constructed from materials with high thermal conductivity to prevent coking by maintaining lower localized wall temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If fuel flows intermittently through the secondary fuel flow passage, then power output can be adjusted, but coking occurs due to low fuel velocity and high temperature

Engineering Contradiction:

Improvepower output adjustmentVSAvoidcoking prevention

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent merges the primary and secondary fuel flow passages into a single integrated tubular member structure. The passages are positioned concentrically with the secondary passage surrounding the primary passage, allowing thermal coupling between the two flow paths. This integration enables heat transferred from the primary passage to preheat fuel in the secondary passage, preventing coking while maintaining the ability to adjust power output by controlling flow distribution between passages.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent converts the harmful effect of high temperature in the secondary fuel passage (which causes coking) into a beneficial effect by using thermal coupling with the primary passage. The heat that would otherwise cause fuel degradation is now utilized to preheat fuel in the secondary passage, reducing thermal stress and preventing coking. The high temperature environment, previously a hazard, becomes a resource for improving fuel flow stability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Object-affected harmful factors

If heat shields surround the fuel passages, then fuel is protected from extreme heat, but coking still occurs when wall temperature exceeds maximum value

Engineering Contradiction:

Improveheat protectionVSAvoidcoking prevention

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent introduces thermal coupling as an intermediary mechanism between the primary and secondary fuel passages. Instead of relying solely on passive heat shields that block heat, the system uses the primary fuel passage as an active thermal mediator that transfers heat to the secondary passage. This intermediary approach actively manages temperature distribution, preventing wall temperatures in the secondary passage from exceeding the maximum value that causes coking.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Volume of moving object

If the secondary fuel flow passage is in close proximity to the combustion chamber, then compact design is achieved, but coking occurs due to extreme heat exposure

Engineering Contradiction:

Improveinjector compactnessVSAvoidcoking prevention

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent combines the thermal management function with the compact structural design by integrating the primary and secondary passages concentrically within the tubular member. This merged structure allows the secondary passage to be positioned close to the combustion chamber for compactness while the primary passage serves as an internal thermal management system, transferring heat away from the secondary passage walls to prevent coking.

Inventive Principle:

Principle #5Merging (Combining)

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 prevents coking in both primary and secondary fuel flow passages by maintaining higher fuel flow velocities and enhanced heat transfer, ensuring continuous operation and reducing the risk of fuel deposition.

Implementation Method 1

the fuel tube is configured to facilitate heat transfer between the primary fuel flow passage and the secondary fuel flow passage by means of conduction and/or convection

Methodology Applied

Scientific EffectConduction: Conduction (thermal)

Implementation Method 2

the fuel tube is configured to facilitate heat transfer between the primary fuel flow passage and the secondary fuel flow passage by means of conduction and/or convection

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS8443608B2Feed arm for a multiple circuit fuel injector

Publication Date: 2013.05.21 COLLINS ENGINE NOZZLES INC

AI summary

A feed arm for a multiple circuit fuel injector of a gas turbine engine. The feed arm includes an elongated tubular sleeve having a central bore with an interior wall defining an inner diameter, and an elongated fuel tube positioned within the bore of the tubular sleeve. The fuel tube includes a tubular wall defining an outer diameter, which is substantially equal to the inner diameter of the central bore. A primary fuel flow passage is formed within the tubular wall of the fuel tube and bounded by the interior wall of the tubular sleeve, and the primary fuel flow passage circumferentially extends around the fuel tube at least once along the axial length of the fuel tube. A secondary fuel flow passage extends through a central portion of the fuel tube, and the fuel tube is configured to facilitate heat transfer by conduction and/or convection.