Variable-Geometry Ducted Fan for VTOL Efficiency
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Solution Overview
Problem
Traditional ducted fan designs for vertical take-off and landing (VTOL) air vehicles compromise on aerodynamic efficiency for both horizontal and vertical flight modes, as they cannot maximize performance in each operational mode simultaneously.
Innovation Solution
A variable-geometry ducted fan system with a rotatable air duct and a variable-area nozzle that adjusts its exhaust area by pivoting pedals, allowing the fan to optimize airflow for either vertical or horizontal flight modes, thereby enhancing aerodynamic efficiency in both modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a traditional ducted fan design is used with fixed geometry, then the structure is simple and easy to manufacture, but the aerodynamic efficiency suffers in both vertical and horizontal flight modes
Solution Approach 1:
The ducted fan employs variable-geometry components including adjustable stators, variable-pitch fan blades, and a variable-area nozzle that can change configuration between vertical and horizontal flight modes. This dynamic adaptability allows the system to optimize aerodynamic efficiency for each flight regime while maintaining a relatively simple base structure.
Solution Approach 2:
The invention changes key geometric parameters of the ducted fan system - specifically the pitch angle of fan blades, the angle of stators, and the cross-sectional area of the nozzle - to optimize performance for different flight modes. These parameter adjustments enable high aerodynamic efficiency in both vertical hovering and horizontal cruising without requiring completely different designs.
2Force
If the ducted fan is optimized for vertical flight, then hover thrust is maximized, but horizontal flight efficiency deteriorates
Solution Approach 1:
The variable-pitch fan blades and adjustable stators allow the system to dynamically reconfigure between vertical and horizontal flight modes. In vertical flight, blades and stators are positioned to maximize thrust generation for hovering. In horizontal flight, they are adjusted to optimize for forward propulsion efficiency, thereby resolving the contradiction between the two flight regimes.
Solution Approach 2:
The ducted fan system is designed as a multi-functional propulsion system that can effectively perform both vertical take-off/landing and horizontal cruising operations. The variable-geometry components enable a single unified system to adapt its characteristics for different flight modes, eliminating the need for separate optimized designs for each mode.
3Productivity
If the ducted fan is optimized for horizontal flight, then cruising efficiency is maximized, but vertical flight performance deteriorates
Solution Approach 1:
The system uses variable-pitch fan blades and adjustable stators that can be reconfigured between horizontal and vertical flight modes. For horizontal cruising, the geometry is optimized for efficient forward propulsion. For vertical flight, the same components are adjusted to maximize thrust generation in the vertical direction, allowing high performance in both regimes.
Solution Approach 2:
The invention adjusts key geometric parameters including fan blade pitch angle and stator angle to optimize performance for different flight modes. These parameter changes enable the system to achieve high cruising efficiency in horizontal flight while maintaining the capability to generate maximum vertical thrust when needed for take-off and hovering.
4Productivity
If a variable-area nozzle is added to the ducted fan, then aerodynamic efficiency improves in both flight modes, but device complexity increases
Solution Approach 1:
The variable-area nozzle uses a simple mechanical linkage system with pedals that can pivot to change the nozzle cross-sectional area. This relatively simple mechanical mechanism enables effective control of exhaust flow area to optimize aerodynamic efficiency in both vertical and horizontal flight modes without introducing excessive complexity.
Solution Approach 2:
The variable-area nozzle changes the exit area parameter of the exhaust flow to optimize performance for different flight conditions. By adjusting this single key parameter through a simple mechanical system, the invention achieves improved aerodynamic efficiency while avoiding the need for complex multi-component control systems.
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 achieves high aerodynamic efficiency in both hovering and high-speed cruising by maximizing thrust in vertical flight and minimizing exhaust area for efficient horizontal flight, enabling operation up to 350 knots with improved hover thrust augmentation and propulsive efficiency.
Implementation Method 1
exiting the air from the variable-geometry ducted fan through the exhaust to generate thrust
Data Source
AI summary
A variable-geometry ducted fan may include an air duct having a longitudinal axis, the air duct including an inlet of the variable-geometry ducted fan, a fan rotatably mounted within the air duct downstream from the inlet, the fan including fan blades defining a fan area, and a variable-area nozzle coupled to the air duct downstream from the fan, the variable-area nozzle including an exhaust of the variable-geometry ducted fan having a variable exhaust area.