Turbojet Nacelle Air Intake Deflection for Thrust Reversal

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Solution Overview

Problem

High bypass ratio turbojet engines face significant challenges in thrust reversal due to conventional systems increasing weight, size, and drag, while existing air intake designs hinder the thrust reversal phase by creating local depressions that reduce performance.

Innovation Solution

An air intake with a deflection device featuring movably mounted deflection members that extend radially to separate the reverse air flow from the internal wall during thrust reversal, maintaining an aerodynamic profile during thrust phases, thereby preventing bypass and local depressions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional thrust reversal system is integrated in the nacelle, then thrust reversal capability is achieved, but weight, overall size and drag are significantly increased

Engineering Contradiction:

Improvethrust reversal capabilityVSAvoidengine weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The air intake structure is designed to serve dual purposes: guiding internal air flow during normal thrust phase and guiding reverse air flow during thrust reversal phase. The same internal wall and air intake lip structure is used for both forward and reverse flow guidance, eliminating the need for separate thrust reversal components and thereby reducing weight.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the thrust reversal function with the existing air intake structure. The internal wall and air intake lip that originally only guided forward air flow are modified to also guide reverse air flow, merging two functions into a single integrated structure, which reduces overall size and weight.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If the reverse air flow bypasses the aerodynamic profile of the air intake, then thrust reversal phase can occur, but a local depression zone is generated that creates upstream suction opposing the thrust reversal

Engineering Contradiction:

Improvethrust reversal phaseVSAvoidupstream suction force

Core Design Contradiction:

Adaptability or versatilityVSForce

Solution Approach 1:

The air intake lip is designed to preliminarily guide the reverse air flow in a controlled manner before it reaches the critical region. By pre-conditioning the flow direction and preventing uncontrolled bypass, the formation of local depression zones is avoided, thereby eliminating the opposing upstream suction force.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the potentially harmful bypass flow that creates depression zones into a beneficial controlled flow pattern. By modifying the air intake geometry, the reverse air flow is channeled to follow the internal wall smoothly, transforming what would be a harmful uncontrolled bypass into a useful controlled flow that enhances thrust reversal without creating opposing forces.

Inventive Principle:

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

3Productivity

If the air intake has an aerodynamic profile for guiding internal air flow, then thrust phase performance is optimized, but the reverse air flow is hindered during thrust reversal phase

Engineering Contradiction:

Improvethrust phase performanceVSAvoidthrust reversal performance

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The air intake structure is designed with dynamic adaptability through its geometric features that respond differently to forward and reverse air flows. The internal wall profile and air intake lip configuration automatically adapt to guide either internal air flow during thrust phase or reverse air flow during thrust reversal phase, maintaining optimal performance in both conditions without requiring active control mechanisms.

Inventive Principle:

Principle #15Dynamics

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

Enhances thrust reversal performance without compromising thrust phase efficiency by ensuring the reverse air flow is properly directed, reducing opposing forces and maintaining aerodynamic integrity.

Implementation Method 1

allow the reverse air flow to be separated from the internal wall to promote the thrust reversal phase

Methodology Applied

Scientific EffectFlow separation: Flow Separation

Implementation Method 2

The air intake 200 has an aerodynamic profile for separating an upstream air flow F into the internal air flow F-INT guided by the internal wall 201

Methodology Applied

Scientific EffectAerodynamic flow guidance: Aerofoil

Data Source

PatentUS11933246B2Turbojet engine comprising a nacelle with an air intake to promote a reversed thrust phase

Publication Date: 2024.03.19 SAFRAN AIRCRAFT ENGINES SAS

AI summary

An aircraft turbojet engine extending along an X axis and comprising a blower configured to provide a reverse thrust and a nacelle comprising an air intake which comprises at least one deflection member movably mounted between a deployed position in which the deflection member projects from the inner wall or from the lip of the air intake in a radially inward direction of deployment facing the X axis or in a longitudinal direction of deployment with respect to the X axis, in order to allow a release of the reverse air flow from the inner wall to support the reverse thrust phase, and a retracted position in which the air intake has an aerodynamic profile so as to guide the internal air flow along the inner wall in order to support the thrust phase.