Thrust Recovery Outflow Valve With Pressure-Responsive Noise Obstacle
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Solution Overview
Problem
Existing thrust recovery valve systems in aircraft face challenges in managing noise generation during airflow discharge, with fixed obstruction elements either reducing tonal noise at lower altitudes or increasing broadband noise at higher altitudes.
Innovation Solution
A thrust recovery valve system with an obstruction system that includes a pivotably coupled gate and a wall surface, where an obstacle extends into the airflow at lower differential pressures to reduce tonal noise and retracts at higher pressures to minimize broadband noise, all while maintaining the system's stationary components relative to the aircraft body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fixed obstruction element is positioned in the airflow path, then tonal noise is reduced at lower altitudes, but broadband noise increases at higher altitudes
Solution Approach 1:
The patent applies the dynamics principle by making the obstruction element movable rather than fixed. The obstacle is positioned to extend into the airflow path at lower altitudes to reduce tonal noise, and retracts from the airflow path at higher altitudes to minimize broadband noise generation. This dynamic adjustment allows the system to adapt to different operating conditions and eliminate the trade-off between tonal and broadband noise reduction.
2Object-affected harmful factors
If an obstacle extends into the airflow, then tonal noise is reduced, but the system complexity increases due to additional positioning mechanisms
Solution Approach 1:
The patent applies parameter changes by utilizing differential pressure across the valve as the controlling parameter for obstacle positioning. The system uses the existing pressure differential that occurs during normal valve operation to automatically position the obstacle, eliminating the need for external actuators or complex control systems. This approach reduces device complexity while maintaining the ability to reduce tonal noise effectively.
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 effectively reduces noise propagation into the aircraft cabin by dynamically positioning the obstacle based on differential pressure, enhancing passenger and crew comfort across various flight altitudes.
Implementation Method 1
The acceleration of the airflow may be dependent on a differential pressure across the outflow valve as the airflow flows through the outflow valve. For example, differential pressure may cause the airflow to accelerate to a subsonic velocity, sonic velocity, or supersonic velocity.
Implementation Method 2
The outflow valve may be configured to accelerate the airflow as the airflow flows through the flow passage. The thrust recovery valve system may be configured to transfer a thrust to the aircraft produced by the acceleration of the airflow.
Data Source
AI summary
In some examples, a thrust recovery valve system is configured to use an outflow valve to discharge a fluid flow from a cabin of an aircraft to an external environment surrounding the aircraft. The outflow valve may include a frame supported by a body of the aircraft and a gate configured to displace from the frame to define a flow passage for the discharge of the fluid follow. The thrust recovery valve system includes an obstacle configured to extend into the fluid flow in an extended position and retract from the fluid flow in a retracted position. In examples, the obstacle is configured to extend from and/or retract into a wall surface defined by the frame.