Wing Flow Fence for Spanwise Pressure Gradient Control
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Solution Overview
Problem
Aircraft wings experience flow separation issues due to pressure gradients caused by airflow attack, particularly at leading edge lift bodies, leading to aerodynamic inefficiencies and potential drag increases.
Innovation Solution
A flow fence is strategically positioned along the main wing chordwise direction between the pressure-side and suction-side flow surfaces to impede partial flows, minimizing spanwise pressure gradients and preventing flow separations, especially in areas beyond leading edge lift bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If wing sweep is increased to improve aerodynamic performance, then cruise efficiency is improved, but flow separation occurs at the outer rim due to spanwise pressure gradients
Solution Approach 1:
The flow fence divides the airflow into separate regions, segmenting the spanwise flow component that causes pressure gradients. By placing vertical barriers at specific spanwise locations, the flow is segmented into independent zones that prevent the development of harmful pressure gradients while maintaining the overall wing sweep configuration.
Solution Approach 2:
The flow fence acts as an intermediary element between the swept wing surface and the airflow. It mediates the interaction by providing a physical barrier that redirects spanwise flow components, preventing them from creating adverse pressure gradients at the outer rim while allowing the wing to maintain its efficient swept-back geometry.
2Reliability
If flow separation is prevented using conventional devices (beams, ribbons, delta plates), then flow attachment is improved, but device complexity and drag increase
Solution Approach 1:
Instead of applying complex flow control devices across the entire wing surface, the flow fence applies local quality changes at specific critical locations. The vertical fences are positioned only where spanwise pressure gradients develop (at defined spanwise stations), providing targeted flow control where needed while leaving other areas undisturbed, thus reducing overall device complexity.
Solution Approach 2:
The flow fence changes the flow parameters (direction, velocity distribution) locally at the fence positions by introducing vertical barriers. This parameter change redirects the spanwise flow component and modifies the pressure gradient distribution, preventing flow separation without requiring complex active control systems or extensive structural modifications.
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
The flow fence effectively prevents flow separations across various flight conditions and wing configurations, enhancing aerodynamic performance by maintaining smooth airflow and reducing drag, particularly beneficial for wings with sweep angles greater than 20 degrees.
Implementation Method 1
a pressure gradient directed in the spanwise direction. This pressure gradient comes about due to the fact that the flow forming due to the attack of an airflow on the upper side of the wing
Implementation Method 2
flow separations may temporarily occur at the outer rim of the wing in the presence of certain flight condition ranges or wing configurations such as flap positions
Data Source
AI summary
A wing of an aircraft has a pressure-side flow surface and a suction-side flow surface relative to an assumed main direction of attack and comprises a flow fence disposed on a flow surface, wherein the flow fence extends in the main wing chordwise direction and between a location of the pressure-side flow surface and a location of the suction side flow surface.