Micro-perforated Wing Leading Edge for Laminar Flow Control
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Solution Overview
Problem
Existing aircraft wing designs that aim to achieve laminar flow over aerodynamic surfaces often incorporate complex suction chambers and additional weight, which complicates integration with ice-protection systems and increases drag.
Innovation Solution
An aircraft wing assembly with a leading edge featuring a micro-perforated first flow surface portion that extends only 2% or less of the local chord, allowing for boundary layer suction without suction chambers, combined with strategically located outlets for airflow control and fairings that minimize drag and enhance pressure gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If suction chambers are used to control pressure difference through micro-perforations for laminar flow, then laminar flow is achieved, but device complexity and weight increase
Solution Approach 1:
The invention extracts and eliminates the suction chamber component from the system. Instead of using traditional suction chambers to control pressure difference, the patent uses a simplified micro-perforated skin structure where the pressure difference is naturally controlled by the aerodynamic design and the micro-perforations themselves, removing the need for complex suction chamber assemblies
Solution Approach 2:
The micro-perforated skin structure serves itself by using the natural pressure difference that arises during flight to drive the suction effect. The aerodynamic pressure gradient automatically provides the driving force for boundary layer control without requiring additional active components or complex pressure control systems
2Object-generated harmful factors
If suction chambers are used to maintain laminar flow, then drag is reduced, but weight increases
Solution Approach 1:
The suction chamber structure is completely removed from the design. The weight penalty associated with suction chambers is eliminated while maintaining the drag reduction benefits through the micro-perforated skin design that uses natural aerodynamic pressure differences
Solution Approach 2:
The invention changes the design parameters by using a micro-perforated skin with specific perforation patterns and dimensions that allow effective boundary layer suction without requiring heavy suction chambers. The perforation size, distribution, and geometry are optimized to achieve the desired flow control with minimal structural weight
3Reliability
If micro-perforated surface is extended over large area, then suction effect is enhanced, but manufacturing complexity and weight increase
Solution Approach 1:
The micro-perforated skin is applied locally only in the critical regions where boundary layer control is most beneficial, rather than over the entire wing surface. This localized approach maintains suction effectiveness in key areas while significantly reducing manufacturing complexity and material requirements
Solution Approach 2:
The invention uses partial action by applying micro-perforations only to the extent necessary to achieve laminar flow control in critical regions. Rather than perforating the entire surface, the design uses sufficient but not excessive perforation area to maintain the boundary layer, optimizing the balance between effectiveness and manufacturability
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 design reduces complexity and weight while maintaining sufficient suction for laminar flow, delaying boundary layer transition and reducing drag, thus improving fuel efficiency and reducing the need for additional ice-protection system modifications.
Implementation Method 1
A known mechanism to achieve a certain laminar regime is to dampen growth of small perturbations in the boundary layer by suction through micro perforations in the surface
Implementation Method 2
The restriction of the micro-perforated first flow surface portion to 2% or less of the chord has shown to achieve a pressure difference through the micro-perforations that allows sufficient suctioning of boundary layer air
Implementation Method 3
Laminar boundary layer flow or, in short, laminar flow over an aerodynamic surface is generally associated with less drag than turbulent flow over that aerodynamic surface
Data Source
AI summary
An aircraft wing assembly including a main wing portion, a high-lift device with a flow surface including an upper skin portion and a lower skin portion, wherein the flow surface of the high-lift device comprises a first flow surface portion, a second flow surface portion and a third flow surface portion, wherein the first flow surface portion is micro-perforated for an air inflow, wherein the first flow surface portion extends on the upper skin from the leading edge in chordwise direction for 2% or less of the local chord and extends on the lower skin from the leading edge in chordwise direction for 2% or less of the local chord, and wherein the second flow surface portion is not micro-perforated and extends over the rest of the upper skin portion, and wherein the third flow surface portion is not micro-perforated and extends over the rest of the lower skin portion.