Adaptive Duct Geometries for Proprotor Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ducted rotor systems face performance compromises in various flight modes due to static duct geometry, which is suboptimal for both vertical takeoff and landing (VTOL) and forward flight, leading to inefficiencies in thrust production and increased drag.
Innovation Solution
Incorporation of adaptive geometry devices in the duct, such as hinged noses, Krueger flaps, plain flaps, and Fowler flaps, that can change shape based on flight mode, allowing the duct to adjust its leading edge inner lip radius, chord length, and diffusion angle to optimize performance in VTOL and minimize drag in forward flight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a duct with larger inner lip radius, duct chord length and diffusion angle is used, then performance while hovering in VTOL flight mode is improved, but drag penalty in forward flight mode increases
Solution Approach 1:
The duct geometry is made dynamic through the inclusion of movable adaptive geometry devices (hinged noses, Krueger flaps, plain flaps, Fowler flaps) that can change the duct shape based on flight mode. In VTOL mode, the duct adopts a configuration with larger inner lip radius, chord length, and diffusion angle for improved thrust efficiency. In forward flight mode, the duct transitions to a configuration with reduced dimensions to minimize drag, thus resolving the contradiction between thrust efficiency and drag across different operating conditions.
Solution Approach 2:
The patent changes the geometric parameters of the duct (inner lip radius, chord length, diffusion angle) dynamically based on flight mode requirements. By using actuators to move adaptive geometry devices, the duct transitions between different parameter sets: larger values for VTOL hover performance and smaller values for forward flight efficiency, thereby optimizing performance across both regimes without compromise.
2Device complexity
If a static duct shape is used, then device complexity is reduced, but performance compromises occur in both VTOL and forward flight modes
Solution Approach 1:
The duct transitions from a static to a dynamic configuration by incorporating movable adaptive geometry devices. These devices include hinged noses, Krueger flaps, plain flaps, and Fowler flaps that can be actuated to change the duct shape. Although this increases device complexity, it enables the duct to optimize its performance in both VTOL and forward flight modes, justifying the added complexity through significant performance improvements.
Solution Approach 2:
The duct is segmented into multiple controllable sections through the adaptive geometry devices. Each section (leading edge, trailing edge, intermediate portions) can be independently adjusted to achieve optimal geometry for the current flight mode. This segmentation allows fine-tuned control over the duct's overall shape, enabling performance optimization while maintaining manageable complexity through modular design.
3Adaptability or versatility
If adaptive geometry devices are added to the duct, then flight performance in all modes is improved, but device complexity increases
Solution Approach 1:
The adaptive geometry devices serve multiple functions: they modify the duct geometry for different flight modes, control flow separation, and optimize pressure distribution. By integrating these devices into the duct structure, the system achieves multi-functionality that enables it to adapt to both VTOL and forward flight requirements, justifying the increased complexity through versatile performance enhancement.
Solution Approach 2:
The system employs feedback control where the flight mode is sensed and used to actuate the appropriate adaptive geometry devices to the required position. This feedback mechanism ensures that the duct geometry is automatically optimized for the current operating condition, enhancing adaptability while managing complexity through automated control rather than manual intervention.
Data Source
AI summary
A proprotor system for a ducted aircraft convertible between a vertical takeoff and landing flight mode and a forward flight mode includes a plurality of proprotor blades and a duct surrounding the proprotor blades. The duct includes an adaptive geometry device movable into various positions including a hover position and a cruise position. One or more actuators coupled to the adaptive geometry device are configured to move the adaptive geometry device between the hover position and the cruise position based on the flight mode of the ducted aircraft, thereby improving flight performance of the ducted aircraft.