Variable Geometry Flush Boundary Diverter for Aircraft Engine Inlets
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Solution Overview
Problem
Military aircraft face a trade-off between efficient engine performance and survivability due to the observability issues caused by boundary layer diverters, which can increase the risk of being detected and damaged.
Innovation Solution
A variable-geometry airflow diverter system with a moveable door or occlusion device that can be opened to direct boundary layer air away from the engine inlet, improving engine performance, and closed to reduce observability by sealing the upstream passage, thereby enhancing survivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a boundary layer diverter is installed to improve engine performance, then engine efficiency is improved, but aircraft observability increases and survivability decreases
Solution Approach 1:
The boundary layer diverter is designed with movable components (doors, flaps, or panels) that can dynamically change their configuration between open and closed positions. This allows the aircraft to optimize engine performance when needed while maintaining low observability when survivability is prioritized, transforming a static structure into an adaptive system that responds to operational requirements.
Solution Approach 2:
The diverter structure is divided into multiple segmented sections with independent movable elements rather than a single fixed structure. This segmentation allows selective opening or closing of different portions of the diverter, enabling fine-tuned control over both engine performance optimization and observability reduction based on specific flight conditions and threat levels.
2Productivity
If the diverter passageway entrance is made visible to improve airflow intake, then engine performance is enhanced, but the aircraft becomes more detectable from below or in front
Solution Approach 1:
The diverter passageway entrances are positioned and oriented in three-dimensional space to exploit angular relationships. By locating entrances on upper surfaces or at angles that are not visible from below or frontal views, the design allows effective airflow intake while maintaining stealth characteristics when viewed from critical detection angles.
Solution Approach 2:
Different portions of the aircraft surface have different properties - some areas have open diverter entrances for optimal airflow, while other areas maintain closed or concealed configurations for low observability. This local differentiation allows the aircraft to optimize performance at specific locations without compromising overall stealth characteristics.
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 allows for alternating configurations to optimize engine performance and survivability by selectively diverting boundary layer air, resulting in improved engine efficiency and reduced visibility, thus enhancing the aircraft's operational capabilities.
Implementation Method 1
the boundary layer of air closest to the surface of the aircraft experiences drag. This drag reduces the speed of the air in the boundary layer with respect to the free stream of air farther away from the surface of the aircraft.
Implementation Method 2
the boundary layer of air closest to the surface of the aircraft experiences drag. This drag reduces the speed of the air in the boundary layer
Data Source
AI summary
An airflow diverter system for an aircraft may include an external aircraft surface upstream from an engine inlet and a passage having an upstream opening adjacent the engine inlet. The passage may be configured to channel boundary airflow from the external aircraft surface away from the engine inlet. The diverter system may include an occlusion device configured to selectively open and close the opening to the passage.