Active Bleed Airfoil Boundary Layer Control
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Solution Overview
Problem
Conventional suction devices for airfoil boundary layer control are complex, large, and heavy, and fail to effectively manage fluid flow separation, leading to increased drag, reduced lift, and decreased control effectiveness, especially at abrupt surface turns or shock waves.
Innovation Solution
An active airfoil boundary layer control system featuring a housing with an induction wall, exhaust wall, and a chamber containing zero-net-mass-flux actuators that induct and exhaust fluid through strategically positioned orifices and nozzles, integrated with a bleed path to actively manage fluid flow and prevent separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional suction devices are used for boundary layer control, then fluid flow separation can be managed, but the devices become complex, large, and heavy
Solution Approach 1:
The induction wall is made porous to allow boundary layer fluid to be inducted through the wall surface itself, eliminating the need for separate suction ports and complex internal piping. This integrates the suction function directly into the wall structure, reducing device complexity while maintaining control effectiveness
Solution Approach 2:
The invention extracts only the essential suction function from complex conventional devices and implements it through a simplified porous wall structure with minimal internal components (chamber and exhaust port), achieving boundary layer control with a much simpler device configuration
2Reliability
If conventional suction devices are used for boundary layer control, then fluid flow separation can be managed, but the devices become large and heavy
Solution Approach 1:
The porous induction wall replaces heavy solid walls with suction ports, allowing the structure to be lighter while maintaining the suction function. The porous material itself provides the flow control mechanism without requiring heavy internal components
Solution Approach 2:
By extracting and eliminating unnecessary components from conventional suction devices, the invention achieves boundary layer control with a significantly reduced weight structure consisting only of the porous wall, chamber, and exhaust port
3Productivity
If boundary layer separation occurs at abrupt surface turns or shock waves, then drag increases and lift reduces, but complex suction devices are required to prevent this
Solution Approach 1:
The porous induction wall provides distributed suction across the surface, effectively managing boundary layer separation at abrupt turns and shock waves without requiring complex localized suction devices. This maintains aerodynamic efficiency with a simple structure
Solution Approach 2:
The porous wall structure serves multiple functions: it provides structural support, enables boundary layer suction, and controls flow separation at various locations (abrupt turns, shock waves) simultaneously, eliminating the need for multiple specialized devices
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 system effectively reduces drag, increases lift, and enhances control effectiveness by actively controlling the boundary layer, preventing separation and improving efficiency, particularly in turbulent flows, while being lightweight and cost-effective.
Implementation Method 1
suction devices are used to remove boundary layer at strategic locations on airfoil surfaces to maintain attached fluid flow and thereby delay and/or reduce flow separation
Implementation Method 2
the induction wall includes a gas permeable surface
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
An airfoil active bleed system and related method. A housing includes an induction wall (39), an exhaust wall (40a,b) having one or more exhaust ports (44), and a chamber (41) between the induction and exhaust walls. Zero-net-mass-flux actuators (48) are located in the chamber and configured and positioned to collectively induct fluid through the induction wall (39) and selectively exhaust fluid through the exhaust port(s) (44).