Fluidic Boundary Layer Control on Multi-Element Aircraft Wings
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Solution Overview
Problem
Existing systems for controlling boundary layer flow over aircraft wings face challenges such as unsteady forces and moments from oscillatory actuators, structural integrity issues, and limitations in energy output and safety concerns with combustion-based systems, which hinder their practicality and market acceptance.
Innovation Solution
A system employing fluidic devices with zero net mass flow, integrated into multi-element aircraft wings, that selectively control fluid flow through ports on the slat, main wing element, and flap to regulate boundary layer flow, using electrically powered pumps for continuous ingestion and ejection, and employing various port configurations to enhance aerodynamic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oscillatory actuators are used to control boundary layer flow, then flow manipulation capability is improved, but unsteady forces and moments increase causing structural integrity issues
Solution Approach 1:
The patent employs oscillatory actuators that periodically ingest and eject fluid through ports in the wing structure. This periodic action creates unsteady flow manipulation capability while the system is designed to accommodate the resulting unsteady forces and moments through proper structural integration, resolving the contradiction between flow control effectiveness and structural integrity
Solution Approach 2:
The actuators utilize the boundary layer flow itself as the working fluid, ingesting it at one location and ejecting it at another. This self-service approach eliminates the need for external fluid sources or complex plumbing systems, allowing the system to achieve flow manipulation capability while maintaining structural simplicity and integrity
2Power
If combustion-powered actuators are used to increase jet velocity, then energy output is improved, but safety hazards and system complexity increase
Solution Approach 1:
The patent replaces combustion-powered actuators with electrically driven actuators that use electromagnetic or piezoelectric mechanisms to generate fluid ejection. This substitution eliminates combustion-related safety hazards such as fire risks and explosive hazards while still achieving sufficient jet velocity through controlled diaphragm or piston motion, thereby resolving the contradiction between power output and safety
Solution Approach 2:
The electrically driven actuators use simple, robust components such as diaphragms or pistons that can be easily replaced if needed, rather than complex combustion systems. This approach reduces safety hazards and system complexity while maintaining adequate jet velocity for flow control applications
3Object-affected harmful factors
If electrically driven actuators with limited displacement are used, then safety is improved, but maximum jet velocity and energy output are limited
Solution Approach 1:
The patent employs dynamic amplification techniques where the actuator operates at resonant frequencies to maximize jet velocity output for a given displacement amplitude. By optimizing the oscillation frequency and utilizing the natural dynamics of the diaphragm or piston system, the actuators achieve higher jet velocities despite limited physical displacement, thereby resolving the contradiction between safety and power output
Solution Approach 2:
The system optimizes key parameters such as oscillation frequency, port geometry, and chamber volume to maximize jet velocity within the constraints of safe, electrically driven actuation. By carefully tuning these parameters, the actuators achieve adequate jet velocity for effective flow control while maintaining safety through the use of non-combustion-based mechanisms
4Device complexity
If fluidic actuators with Zero-Net-Mass-Flow are used, then system complexity is reduced, but ability to alter viscous flow characteristics is limited
Solution Approach 1:
The patent employs multi-element wing configurations with actuators distributed across slats, main wing elements, and flaps. This spatial distribution in multiple dimensions allows the Zero-Net-Mass-Flow actuators to effectively control viscous flow characteristics across the entire wing surface, compensating for the limitations of individual actuators and achieving overall flow control effectiveness without increasing system complexity
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 significantly improves lift and reduces drag, achieving aerodynamic performance beyond inviscid levels, with reduced structural fatigue and safety risks, while eliminating the need for external fluid sources and complex plumbing.
Implementation Method 1
one or more suction openings arranged in spanwise direction near the wing trailing edge... The suction and discharge openings are connected by a conduit running from the trailing edge towards the leading edge. A rotary piston pump is arranged in the conduit to draw in boundary layer air through the trailing edge suction opening(s)
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5C
AI summary
A system and method for controlling boundary layer flow over an aircraft wing are provided. The system includes at least one wing element (12, 14, 16) , and a plurality of ports (s1, s2, m2, m3, fl, f2) defined in the wing element and in fluid communication with one another. The system also includes at least one fluidic device operable to continuously ingest the fluid through at least one of the ports and eject the fluid out of at least one other port to control boundary layer flow of the fluid over the wing element .