Integrated Fuel Feed Passages for Sequential Injector Testing

Solution Overview

Problem

Conventional fluid dispensing systems in attritable aircraft engines are complex, expensive, and difficult to maintain due to numerous parts, making them heavy, costly, and time-consuming to manufacture and test, with existing inspection methods like CT scanning being inefficient and costly.

Innovation Solution

An additively manufactured attritable engine with integrated fuel feed passages allows for sequential flow testing of individual injectors by inducing a phase change in the flow test fluid, using cooling to block flow in all but one injector at a time, enabling efficient and cost-effective inspection and testing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional fluid dispensing systems with multiple parts are used, then the system can be assembled with standard components, but the manufacturing time and cost increase significantly due to brazing operations

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidmanufacturing time

Core Design Contradiction:

Ease of manufactureVSLoss of time

Solution Approach 1:

The fuel feed passages are integrated directly into the engine case wall structure, merging the fuel delivery function with the structural component. This eliminates separate fuel rails and reduces the number of parts from 10+ to a single integrated component, removing brazing operations and significantly reducing manufacturing time and cost

Inventive Principle:

Principle #5Merging (Combining)

2Ease of manufacture

If conventional fuel dispensing systems with multiple parts are used, then the system can be assembled with standard components, but the weight increases due to additional parts and assembly materials

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidsystem weight

Core Design Contradiction:

Ease of manufactureVSWeight of stationary object

Solution Approach 1:

The fuel feed passages are integrated directly into the engine case wall structure, merging the fuel delivery function with the structural component. This eliminates separate fuel rails and reduces the number of parts from 10+ to a single integrated component, removing brazing operations and significantly reducing manufacturing time and cost

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If CT scanning is used to inspect each injector, then complete inspection coverage is achieved, but the inspection time and cost increase significantly

Engineering Contradiction:

Improveinspection completenessVSAvoidinspection time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The inspection process is segmented by isolating each injector individually through selective freezing. By cooling the engine case wall to freeze fuel in all passages except one, inspectors can test each injector separately using simple flow measurement, replacing complex CT scanning with a sequential, time-efficient process

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The complex CT scanning system is replaced with a simple mechanical flow testing approach. By using thermal cooling to isolate passages and measuring fuel flow through individual injectors, the inspection method substitutes advanced imaging with basic mechanical measurement, dramatically reducing cost and time

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Ease of manufacture

If conventional fuel dispensing systems are used, then the system can be assembled with standard components, but the maintenance and repair costs increase due to multiple operating parts

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidmaintenance cost

Core Design Contradiction:

Ease of manufactureVSEase of repair

Solution Approach 1:

The fuel feed passages are integrated directly into the engine case wall structure, merging the fuel delivery function with the structural component. This eliminates separate fuel rails and reduces the number of parts from 10+ to a single integrated component, removing brazing operations and significantly reducing manufacturing time and cost

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

This method simplifies manufacturing, reduces maintenance costs, and allows for faster, more affordable inspection of each injector, improving the robustness and reliability of the fluid dispensing system while meeting stringent tolerance requirements.

Implementation Method 1

inducing a phase change to a flow test fluid in each of (N−1) fuel feed passages, which prevents flow through each of (N−1) injectors

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 2

applying cooling to an exterior surface adjacent to each fuel feed passage for each of (N−1) injectors and inducing a phase change to a flow test fluid

Methodology Applied

Scientific EffectFreezing: Freezing

Data Source

PatentUS11465247B2Fuel feed passages for an attritable engine

Publication Date: 2022.10.11 RTX CORP

AI summary

An additively manufactured attritable engine includes a compressor section, a combustion section, a turbine section, and an engine case wall, which surrounds the compressor section, the combustion section, and the turbine section. The engine case wall includes a first cavity embedded in the engine case wall that defines an injector that is in fluid communication with the combustion section. The engine case wall includes a second cavity embedded within the engine case wall and defines a fuel feed passage that is in thermal communication through the exterior surface of the engine case wall.