Adjustable Nacelle Chines for Vortex Control

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Solution Overview

Problem

Aircraft nacelles with conventional chines face limitations in adjusting the vortex position and strength during flight, leading to suboptimal near-stall pitch control and reduced maximum lift capacity due to fixed positions and binary control of vortex generation.

Innovation Solution

The implementation of adjustable chines that can be rotated or translated relative to the nacelle, allowing for granular adjustment of vortex position and strength through a control system, enabling precise control of vortex generation in response to changing flight conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional fixed chines are installed on the nacelle to generate vortices for delaying stall, then the wing lift capacity at high angles of attack is improved, but the aerodynamic drag during cruise, takeoff and landing increases adversely

Engineering Contradiction:

Improvewing lift capacityVSAvoidaerodynamic drag

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The chine is made rotatable relative to the nacelle, transitioning from a fixed to a dynamic configuration. This allows the chine to be positioned at different angles: deployed at high angles of attack to generate vortices and delay stall, and retracted or adjusted during cruise to minimize aerodynamic drag. The dynamic adjustment resolves the contradiction between needing vortex generation for lift and minimizing drag for efficiency.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If conventional fixed chines are positioned to optimize vortex generation for stall delay, then the near-stall pitch control is improved, but the pitch characteristics at angles of attack beyond stall become unacceptable

Engineering Contradiction:

Improvenear-stall pitch controlVSAvoidpitch characteristics at post-stall angles

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The rotatable chine enables dynamic repositioning to adjust pitch characteristics. At near-stall angles, the chine is positioned to generate vortices that improve pitch control. Beyond stall, the chine can be repositioned to generate a nose-down pitching moment, providing acceptable pitch characteristics across the full range of angles of attack, thus resolving the contradiction between near-stall and post-stall performance.

Inventive Principle:

Principle #15Dynamics

3Strength

If the chine is configured to generate strong vortices for delaying stall, then the maximum lift capacity increases, but the aerodynamic drag penalty increases

Engineering Contradiction:

Improvemaximum lift capacityVSAvoidaerodynamic drag

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The rotatable chine allows the aircraft to have strong vortex generation capability when needed (at high angles of attack) while minimizing drag during normal cruise operations. The chine can be deployed to its full effective position only during critical phases of flight, and retracted or adjusted to a low-drag configuration during efficient cruise, thus resolving the energy loss contradiction.

Inventive Principle:

Principle #15Dynamics

4Device complexity

If binary control of vortex generation is used with fixed chines, then the control system is simple, but the ability to adjust vortex position and strength in response to changing flight conditions is limited

Engineering Contradiction:

Improvecontrol system complexityVSAvoidvortex position and strength adjustment

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The rotatable chine introduces a continuous degree of freedom for vortex control, moving from binary (on/off) to analog (variable position and strength) control. This allows granular adjustment of vortex characteristics in response to varying flight conditions, significantly improving adaptability while adding only a single rotational degree of freedom to the control system.

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

This solution enhances near-stall pitch control and increases the maximum lift capacity by allowing active adjustment of vortex position and strength, improving aircraft performance across various flight angles.

Implementation Method 1

The chine is typically mounted on a side of the nacelle and is sized and positioned to control the separation of the flow over the wing by generating a vortex that interacts beneficially with a boundary layer of the upper surface of the wing

Methodology Applied

Scientific EffectVortex generation: Vortex Ring

Implementation Method 2

generating a vortex that interacts beneficially with a boundary layer of the upper surface of the wing in order to reduce flow separation

Methodology Applied

Scientific EffectBoundary layer interaction: Boundary Layer

Implementation Method 3

the chine is rotatable relative to the nacelle about an axis of rotation. In some disclosed examples, the axis of rotation is substantially perpendicular to a plane of the chine defined by an outer mold line of the chine

Methodology Applied

Scientific EffectRotational movement:

Data Source

PatentUS11591097B2Aircraft nacelles having adjustable chines

Publication Date: 2023.02.28 THE BOEING CO

AI summary

Aircraft nacelles having adjustable chines are described. An example apparatus includes a chine coupled to a nacelle. The chine is oriented along a fore-aft direction. The chine is rotatable relative to the nacelle about an axis of rotation. The axis of rotation is substantially perpendicular to a plane of the chine defined by an outer mold line of the chine.