Reverse Core Engine Air Intake Particle Separator

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Solution Overview

Problem

The challenge in reducing the size of turbofan engines' core while maintaining efficient rotational speeds of the low pressure spool is hindered by the critical speed limitations, which necessitates compromises in the high pressure spool, such as increased size and weight, to accommodate larger low pressure shaft diameters.

Innovation Solution

The design incorporates a gas turbine engine with a fairing and air intake system that includes an embedded air inlet, a curved duct, and a particle separation outlet, allowing free stream atmospheric air to be supplied to a gas generator, along with a reverse engine core and propulsor section featuring free turbines and fans, enabling efficient airflow and particle management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the core size is reduced to improve engine efficiency, then the low pressure shaft diameter cannot be reduced due to critical speed limitations, requiring increased high pressure spool rotor disk size and weight

Engineering Contradiction:

Improveengine efficiencyVSAvoidhigh pressure spool rotor disk weight

Core Design Contradiction:

ProductivityVSWeight of moving object

Solution Approach 1:

The patent inverts the conventional nested core arrangement by placing the low pressure spool inside the high pressure spool, rather than the traditional high pressure inside low pressure. This inversion allows the low pressure shaft to be positioned where it can maintain sufficient diameter for critical speed requirements while the high pressure components occupy the outer region, resolving the conflict between core size reduction and shaft weight constraints

Inventive Principle:

Principle #13The other way round (Inversion)

2Length of moving object

If the core size is reduced, then the low pressure shaft diameter must be maintained, which compromises the high pressure spool design

Engineering Contradiction:

Improvecore diameterVSAvoidhigh pressure spool configuration

Core Design Contradiction:

Length of moving objectVSDevice complexity

Solution Approach 1:

The patent applies nested doll principle by placing the low pressure spool assembly inside the high pressure spool assembly, creating a concentric configuration. This allows both spools to occupy the same axial space while maintaining their respective diameter requirements, enabling core size reduction without compromising low pressure shaft integrity

Inventive Principle:

Principle #7Nested doll (Nesting)

3Productivity

If free stream air intake is used for reverse core engine, then particle separation is required to prevent engine damage

Engineering Contradiction:

Improveairflow efficiencyVSAvoidparticle contamination

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts particles from the free stream air intake flow using a particle separator positioned at the air inlet. This separates the harmful particles from the beneficial airflow, allowing efficient air intake while protecting the engine from particle damage through physical removal of contaminants before they can enter the engine core

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS9644537B2Free stream intake with particle separator for reverse core engine

Publication Date: 2017.05.09 RTX CORP

AI summary

A gas turbine engine has a fairing and an air intake that includes an air inlet embedded within the fairing for supplying free stream atmospheric air to a gas generator.