Adjustable Nacelle Chines for Vortex Control
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Solution Overview
Problem
Conventional aircraft nacelle chines lack the ability to actively adjust and tune the position and strength of the vortex generated during flight, providing only near-binary control, which limits near-stall pitch control and maximum lift capacity.
Innovation Solution
The implementation of adjustable chines on aircraft nacelles, coupled with a control system that allows for granular adjustment of the chine's position and vortex strength, enabling precise control of the vortex generated over the wing surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional fixed chines are installed on the nacelle to generate vortices for delaying stall, then the wing lift capacity at high angles of attack is improved, but the aerodynamic drag during cruise, takeoff and landing increases
Solution Approach 1:
The chine is made adjustable relative to the nacelle, allowing it to be positioned in different locations along the nacelle surface. This enables the chine to be deployed when vortex generation is needed (high angle of attack) and repositioned or stowed when vortex generation is undesirable (cruise, takeoff, landing), thus dynamically adapting to different flight conditions to reduce drag while maintaining lift capacity benefits
2Strength
If the chine is positioned to generate optimal vortex for stall delay, then the wing lift capacity is maximized, but the airplane pitch characteristics at angles of attack beyond stall become unacceptable
Solution Approach 1:
The adjustable chine position allows for dynamic control of vortex generation characteristics. By repositioning the chine along the nacelle, the vortex strength and location can be modified to achieve acceptable pitch characteristics at post-stall angles of attack while still maintaining adequate lift capacity, thus dynamically balancing performance and stability requirements
3Reliability
If the chine extends outwardly into the airflow to generate vortex, then the flow separation is controlled beneficially, but the aerodynamic drag penalty increases
Solution Approach 1:
The chine's ability to be repositioned relative to the nacelle allows it to be placed in locations where it can effectively control flow separation and generate beneficial vortices. When vortex generation is not needed, the chine can be repositioned to minimize its interference with the airflow, thereby reducing the aerodynamic drag penalty while maintaining flow separation control capability when required
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 solution enhances near-stall pitch control and increases the maximum coefficient of lift by allowing for active adjustment of the vortex, improving aerodynamic performance across various flight conditions.
Implementation Method 1
the chine is sized and positioned to control the separation of the flow over the wing by generating a vortex that interacts beneficially with a boundary layer of the upper surface of the wing
Implementation Method 2
a vortex that interacts beneficially with a boundary layer of the upper surface of the wing in order to reduce flow separation
Data Source
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AI summary
Aircraft nacelles having adjustable chines are described. An example apparatus includes a chine coupled to a nacelle, the chine rotatable relative to the nacelle about an axis of rotation, wherein: the chine is oriented along a fore-aft direction and the axis of rotation substantially perpendicular to a plane of the chine defined by an outer mold line of the chine; or the axis of rotation is substantially perpendicular to a local area of an outer surface of the nacelle.