Variable Area Fan Nozzle Actuation With Fixed-Structure Fluid Power
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Solution Overview
Problem
Existing VAFN actuation systems for aircraft engines are heavy, complex, and difficult to maintain due to actuators being mounted on the translating sleeve, which increases drag, weight, and requires cumbersome couplings for power transfer.
Innovation Solution
A VAFN actuation system with fluid-power actuators mounted on the nacelle fixed structure, allowing for a lightweight, less complex design that includes a cylinder with pistons and ports for controlled movement of the VAFN cowl, using pneumatic or hydraulic fluid to optimize engine performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If actuators are mounted on the translating sleeve, then the VAFN cowl can be actuated, but the system weight increases and drag is increased
Solution Approach 1:
The actuator is extracted from the translating sleeve and mounted on the fixed structure instead. This removes the weight penalty of having the actuator move with the translating sleeve and eliminates the need for fairings that protrude into the air stream, thereby reducing both weight and drag while maintaining the actuation capability.
Solution Approach 2:
A coupling mechanism is introduced as an intermediary between the fixed structure and the translating sleeve. This coupling allows power transfer from the stationary actuator to the moving VAFN cowl without requiring the actuator itself to be mounted on the translating sleeve, thus resolving the weight and drag issues.
2Power
If couplings are used to transfer power from fixed structure to translating sleeve, then power transfer is enabled, but system complexity and weight increase
Solution Approach 1:
The patent employs pneumatic or hydraulic couplings to transfer power from the fixed structure to the translating sleeve. These fluid-based couplings are simpler and lighter than mechanical alternatives, reducing system complexity and weight while maintaining effective power transfer for actuating the VAFN cowl.
3Reliability
If mechanical couplings are used for power transfer, then power transmission is reliable, but maintenance difficulty increases
Solution Approach 1:
By using pneumatic or hydraulic couplings instead of mechanical ones, the system achieves reliable power transmission through fluid pressure while significantly simplifying maintenance. These fluid couplings have fewer moving parts and no mechanical wear components, making them easier to service and more reliable over time.
4Ease of operation
If multiple components with coordinated movement are used, then actuation control is achieved, but device complexity increases
Solution Approach 1:
The actuator is extracted from the translating sleeve assembly, separating the power source from the moving components. This reduces the number of components that require coordinated movement and simplifies the overall system architecture while maintaining precise actuation control through the coupling mechanism.
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 reduces engine fuel consumption, decreases noise, and simplifies maintenance by eliminating the need for cumbersome couplings, while providing precise control over the VAFN cowl position.
Implementation Method 1
The actuation system includes a fluid-power VAFN actuator... Each chamber has two ports through which fluid enters and exits in order to control the position of the piston within
Data Source
AI summary
A variable area fan nozzle (VAFN) actuation system is disclosed. The VAFN actuation system is part of an aircraft nacelle, comprising a thrust reverser translating sleeve and a VAFN cowl. The system may translate the VAFN cowl to various positions to optimize engine performance. The system works in two phases. The first phase occurs when the translating sleeve is stowed. During this time, a linear, fluid-pressure VAFN actuator with multiple pistons may translate the VAFN cowl forward and aftward, and hold it in various fixed positions. The second phase occurs when the translating sleeve deploys and then stows.During this time, the actuator may allow the VAFN cowl to travel with the translating sleeve in a controlled manner. When the translating sleeve deploys, the VAFN cowl is pushed aftward by the translating sleeve. When the translating sleeve stows, the VAFN cowl is pulled forward with it.