Leading Edge Laminar Flow Control with Radial Structural Elements

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Solution Overview

Problem

Current hybrid laminar flow control (HLFC) systems for aircraft leading edges are complex and costly to manufacture, with mechanical joints reducing the effective suction surface and incurring a significant weight penalty, which undermines the drag reduction benefits and makes implementation impractical.

Innovation Solution

A leading edge section with a micro-drilled outer skin and internal suction chambers, utilizing composite materials and radial structural elements to create a laminar flow control system that integrates aerodynamic profiles and optimizes structural support for bird strike resistance, allowing easier inspection and maintenance, and reducing assembly complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional HLFC systems use mechanical joints for assembly, then manufacturing and assembly are simplified, but the effective suction surface is reduced and weight penalty increases

Engineering Contradiction:
Improveassembly simplicityVSAvoideffective suction surface
Core Design Contradiction:
Ease of manufactureVSArea of stationary object

Solution Approach 1:

The patent integrates the suction chambers directly into the leading edge structure itself, eliminating the need for separate mechanical joints. The leading edge is designed as a unified structure where the suction chambers are formed as integral parts, thereby preserving the full suction surface area without interruptions from joints or fasteners.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The suction chambers are nested within the leading edge structure, with chambers positioned at different depths and orientations. This nested arrangement allows multiple suction zones to be incorporated within the limited leading edge volume while maintaining full surface utilization and avoiding the need for external mechanical connections.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Ease of manufacture

If traditional HLFC systems use mechanical joints for assembly, then manufacturing is simplified, but weight penalty significantly increases

Engineering Contradiction:
Improveassembly simplicityVSAvoidleading edge weight
Core Design Contradiction:
Ease of manufactureVSWeight of moving object

Solution Approach 1:

By merging the suction chambers with the leading edge structure into a single integrated component, the patent eliminates the weight of multiple separate parts and their connecting mechanical joints. The unified structure reduces overall weight while maintaining manufacturing feasibility through modern composite fabrication techniques.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs composite materials for the leading edge structure, which provide high strength-to-weight ratio. The composite construction allows for complex integrated geometries including nested suction chambers without requiring heavy mechanical fasteners or joints, thereby reducing overall weight while maintaining structural integrity.

Inventive Principle:
Principle #40Composite materials

3Weight of moving object

If suction chambers are integrated into leading edge structure, then weight and assembly complexity are reduced, but manufacturing precision requirements increase

Engineering Contradiction:
Improveleading edge weightVSAvoidchamber configuration precision
Core Design Contradiction:
Weight of moving objectVSManufacturing precision

Solution Approach 1:

Composite material fabrication processes such as autoclave curing and resin transfer molding inherently provide high dimensional accuracy and surface quality. These processes can directly form the complex nested chamber geometries with the required precision, eliminating the need for post-assembly adjustments or tight tolerances on mechanical joints.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent optimizes the chamber size parameters and spatial arrangement to work effectively with the chosen composite manufacturing process. By adjusting chamber dimensions, positions, and configurations to match the capabilities of composite fabrication, the design achieves the required precision through process-native accuracy rather than requiring ultra-precise mechanical assembly.

Inventive Principle:
Principle #35Parameter changes

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 configuration reduces manufacturing costs, simplifies assembly and inspection, enhances structural integrity for bird strikes, and maintains aerodynamic benefits while minimizing drag, thus improving aircraft performance and fuel efficiency.

Implementation Method 1

The suction chambers (4) are arranged and dimensioned to obtain different pressure gradients over the outer wet surface of the leading edge

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

a correctly profiled wing or lifting surface contour, to generate a suitable pressure gradient, thus maintaining the laminar flow aft of the suction area

Methodology Applied
Scientific EffectLaminar flow: Laminar Flow

Implementation Method 3

Laminar Flow Control (LFC) which relies on a relatively small amount of air being sucked through a perforated skin to suppress boundary layer instabilities

Methodology Applied
Scientific EffectSuction: Suction

Implementation Method 4

Since air laminar boundary layers create less friction at the aircraft surfaces than air turbulent boundary layers

Methodology Applied
Scientific EffectBoundary layer: Boundary Layer

Data Source

PatentEP3173328B1Leading edge with laminar flow control
Publication Date: 2020.01.01 AIRBUS OPERATIONS SL
  • EP3173328B1 patent drawingFigure 1A~1C
  • EP3173328B1 patent drawingFigure 2A~2C
  • EP3173328B1 patent drawingFigure 3~4A

AI summary

The present invention refers to the configuration of a leading edge section (1) with laminar flow control, wherein the leading edge comprises: a perforated outer skin (2), an inner surface (3), a plurality of suction chambers (4) formed between the outer skin (2) and the inner surface (3) and a plurality of radial structural elements (5) to withstand structural loads at the leading edge. The radial structural elements (5) are arranged to define the suction chambers (4) together with the outer skin (2) and the inner surface (3), and the radial structural elements (5) and/or the inner surface (3) are perforated, such that an exterior region of the leading edge is communicated with an interior region of the leading edge through said suction chambers (4). The invention provides an optimized leading edge with a laminarflow control system, from a structural point of view, including improved bird impact performance.