Variable-Porosity Panel System for Aircraft Noise Mitigation
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Solution Overview
Problem
Modern aircraft designs with shorter engine inlets and more compact nacelles face increased engine noise due to reduced acoustic treatment area, and existing passive porosity solutions compromise noise mitigation across various flight conditions.
Innovation Solution
A variable-porosity panel system using a shape memory alloy (SMA) actuator to dynamically adjust the porosity of aircraft surfaces by aligning and misaligning pores, allowing for real-time modulation of airflow and noise attenuation based on flight conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If shorter engine inlets and more compact nacelles are used to improve aircraft performance, then aircraft performance is improved, but engine noise increases due to reduced acoustic treatment area
Solution Approach 1:
The patent applies a variable-porosity panel system that can dynamically adjust its porosity level based on flight conditions. The panel transitions from a fixed porosity design to a dynamic system where the porosity can be changed in real-time, allowing the same acoustic treatment area to be optimized for different operating regimes (takeoff, cruise, landing) despite the reduced overall size of the engine inlet and nacelle.
Solution Approach 2:
The patent changes the porosity parameter of the acoustic treatment panel from a fixed value to a variable parameter. By using a variable-porosity panel system with movable panels or adjustable pore structures, the acoustic treatment can adapt its porosity level to match different flight conditions, thereby maintaining effective noise mitigation across all phases of flight despite the reduced acoustic treatment area.
2Object-affected harmful factors
If fixed porosity acoustic liners are used to mitigate fan noise, then acoustic noise is reduced, but effectiveness varies across different flight conditions due to changing fan RPM and in-duct flow
Solution Approach 1:
The patent replaces fixed porosity acoustic liners with a variable-porosity panel system that can adapt its porosity level dynamically. The system includes mechanisms to adjust the porosity of the acoustic treatment panels in real-time, allowing the same acoustic treatment to be optimized for different fan RPM levels and in-duct flow conditions encountered during various phases of flight.
Solution Approach 2:
The patent changes the porosity parameter from a fixed value to a variable parameter that can be adjusted based on flight conditions. The variable-porosity panel system allows the acoustic treatment to modify its porosity level to match the changing acoustic characteristics of the engine across different operating regimes, thereby maintaining consistent noise mitigation effectiveness.
3Strength
If non-porous surfaces are used on aircraft surfaces, then structural integrity is maintained, but air turbulence increases at high velocities due to airflow impact
Solution Approach 1:
The patent applies porous materials to aircraft surfaces, specifically using variable-porosity panels that can be positioned on aerodynamic surfaces. These porous panels allow controlled airflow through the surface, reducing turbulence and shockwaves at high velocities while maintaining the structural integrity of the underlying non-porous structure. The porosity provides aerodynamic benefits without compromising structural strength.
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 mitigates acoustic noise and aerodynamic inefficiencies by optimizing porosity to match specific flight conditions, improving fuel efficiency and reducing turbulence.
Implementation Method 1
Shape memory alloys (referred to equivalently herein as 'SMAs') are a class of active materials that convert thermal energy into mechanical energy. Heating the material above its austenitic transformation temperature induces a change in the SMA microstructure, known as the Shape Memory Effect (SME), which results in a macroscopic shape change to a stable, defined austenitic shape.
Data Source
AI summary
Variable-porosity panel systems and associated methods. A variable-porosity panel system includes a panel assembly with an exterior layer defining a plurality of exterior layer pores and a sliding layer adjacent to the exterior layer and defining a plurality of sliding layer pores. The variable-porosity panel system additionally includes a shape memory alloy (SMA) actuator configured to translate the sliding layer relative to the exterior layer to modulate a porosity of the panel assembly. The SMA actuator includes an SMA element configured to exert an actuation force on the sliding layer and at least partially received within an SMA element receiver of the sliding layer. The SMA element extends out of the sliding layer only at a sliding layer first end. A method of operating the variable-porosity panel system includes assembling the variable-porosity panel system and/or transitioning the panel assembly of the variable-porosity panel system among the plurality of panel configurations.