Rotorcraft Fairing Flap for Cooling Drag Trade-off
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Solution Overview
Problem
The existing aerodynamic devices on rotorcrafts face challenges in optimizing air inlet size for various flight phases, leading to inefficiencies in cooling and propulsion, as well as potential vibration and drag issues due to fluctuating air pressure and flight conditions.
Innovation Solution
The implementation of a rotorcraft with a fairing equipped with moving flaps that automatically adjust their orientation and cross-sectional area in response to airflow, allowing for optimal suction and cooling during hovering and forward flight phases without the need for motor-driven actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a large mouth for the air inlet is used, then head losses are minimized and cooling performance is optimized during hovering, but uncontrolled delivery of cool air at excessive flow rate occurs during forward flight, causing capture drag and vibration
Solution Approach 1:
The patent applies the dynamics principle by replacing the fixed air inlet mouth with movable flaps that can dynamically adjust their position. The flaps are mounted to rotate about a second axis of rotation and automatically orient themselves as a function of the current orientation of the stream of cool air, allowing the effective inlet area to change based on flight conditions. This resolves the contradiction by enabling the system to have a large effective area during hovering (minimizing head losses) and a restricted area during forward flight (minimizing capture drag).
Solution Approach 2:
The patent applies parameter changes by modifying the geometric parameter of the air inlet mouth through movable flaps. The flaps can change the effective cross-sectional area and orientation of the inlet, adapting the parameter to match different flight phases. During hovering, the flaps orient to maximize inlet area for optimal cooling, while during forward flight, they adjust to reduce the effective area and prevent excessive air delivery that causes capture drag.
2Productivity
If a large mouth for the air inlet is used, then optimum operation of the heat exchanger is guaranteed during hovering, but non-negligible capture drag occurs during forward flight
Solution Approach 1:
The movable flaps enable dynamic adjustment of the inlet characteristics to match different operational requirements. During hovering, the flaps position themselves to provide a large effective inlet area, ensuring optimum heat exchanger operation. During forward flight, the flaps automatically adjust to restrict the inlet, preventing the excessive air delivery that causes capture drag, thus resolving the contradiction between cooling performance and drag reduction.
3Loss of energy
If a mouth of small dimensions is used, then head losses occur during hovering affecting fan performance, but flow rate of cool air is minimized during forward flight
Solution Approach 1:
The movable flaps provide dynamic control over the inlet geometry, allowing the system to have a large effective area during hovering to minimize head losses and maintain fan performance, while automatically restricting the area during forward flight to minimize the flow rate of cool air delivered, thus resolving the contradiction between maintaining flow during hovering and minimizing flow during forward flight.
4Device complexity
If a fixed size mouth is used, then the design is simple, but the performance is restricted for different flight phases
Solution Approach 1:
The patent applies dynamics by introducing movable flaps that can automatically adjust the inlet configuration based on flight conditions. While this increases device complexity compared to a fixed inlet, it significantly improves adaptability and versatility, allowing optimal performance during both hovering and forward flight phases. The flaps automatically orient themselves as a function of the stream orientation, providing adaptability without requiring complex control systems.
5Ease of operation
If motor-driven actuators are used to control flaps, then precise control is achieved, but the risk of actuator failure and defective control increases
Solution Approach 1:
The patent applies self-service by designing flaps that automatically orient themselves as a function of the current orientation of the stream of cool air, eliminating the need for motor-driven actuators and their controls. The flaps use the airflow itself as the control mechanism, which inherently adapts to different flight conditions. This resolves the contradiction by removing the reliability issues associated with actuators while maintaining the ability to achieve optimal flap positioning for different flight phases.
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 minimizes head losses and capture drag, ensures optimal cooling and propulsion performance across different flight phases, and reduces the risk of vibration and poor cooling, enhancing the overall aerodynamic design and safety of the rotorcraft.
Implementation Method 1
the moving flap/each moving flap orienting itself automatically and passively as a function of a current orientation of the stream of cool air at the mouth of the air inlet
Data Source
AI summary
A rotorcraft having an aerodynamic device arranged below a rotor, which rotor participates at least in providing lift for the rotorcraft in the air, the rotor being mounted to rotate about a first axis of rotation, the aerodynamic device having a fairing provided with at least one air inlet for enabling a stream of cool air to flow from a region that is situated outside the rotorcraft to another region that is situated inside the rotorcraft; at least at a mouth of the at least one air inlet in the fairing, the aerodynamic device has at least one moving flap that is mounted to move in rotation, the at least one moving flap having at least one degree of freedom of movement in rotation about a second axis of rotation relative to the fairing, and the at least one moving flap orienting itself automatically and passively.