Adjustable Inlet System for Ducted Fan Propulsion
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Solution Overview
Problem
Ducted fan systems face a compromise in performance due to the need for rounded inlet lips for low-speed flight and sharper lips for high-speed flight, leading to suboptimal operation in at least one flight condition, and existing solutions like inflatable lips are prone to failure and foreign object damage.
Innovation Solution
An adjustable size inlet system with a petal array and actuators that change the circumference of the inlet lip, allowing it to transition between a bellmouth and cylindrical profiles to optimize thrust production across various flight conditions, including hovering, low-speed, and high-speed flights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a rounded inlet lip is used, then thrust production at low speeds is improved, but profile drag at high speeds increases
Solution Approach 1:
The inlet lip is designed with movable petals that can dynamically change their position between a rounded configuration for low-speed flight and a sharper configuration for high-speed flight. This dynamic adaptability allows the system to optimize performance across different flight regimes, resolving the contradiction between low-speed thrust production and high-speed drag reduction
Solution Approach 2:
The inlet lip is segmented into multiple movable petals rather than being a single fixed structure. This segmentation allows independent adjustment of each petal to achieve the desired overall shape, enabling transition between rounded and sharp profiles while maintaining structural integrity and aerodynamic efficiency
2Object-generated harmful factors
If a sharper inlet lip is used, then profile drag at high speeds is reduced, but thrust production at low speeds deteriorates
Solution Approach 1:
The inlet lip configuration is made dynamic through movable petals that can be repositioned based on flight conditions. During high-speed flight, the petals are adjusted to form a sharper profile that reduces profile drag, while during low-speed flight, they form a rounded profile that enhances thrust production, thus resolving the performance trade-off
3Shape
If inflatable inlet surfaces are used, then rounded inlet profile at low speeds is achieved, but vulnerability to failure and foreign object damage increases
Solution Approach 1:
The patent replaces the pneumatic/inflatable mechanical system with a structured petal array system. Instead of relying on inflatable membranes that are vulnerable to punctures and failure, the new design uses rigid or semi-rigid petals with mechanical actuation, significantly improving reliability while eliminating the foreign object damage vulnerability associated with inflatable structures
Data Source
AI summary
An adjustable size inlet duct system for a ducted fan propulsion system may change its inlet profile to enhance thrust levels in low-speed and hovering flight conditions and may change its inlet profile to reduce drag to permit faster flight speeds at higher operating speeds. The adjustable size inlet duct system may include duct petals and associated actuators. During slow speed flight, the petals may expand to generate a rounded large inlet area bellmouth profile. At higher flight speeds, the petals may contract to reduce the profile drag of the duct in forward flight. An optional exterior bypass duct may be included to provide additional thrust in excess of the thrust provided by the ducted fan. An optional annular electric motor housed in the exterior bypass duct may be included to generate still more excess thrust.