Optimal passive metamaterial selection for electric-Vertical-Take-Off-and-Landing aircraft: A filtering concepta)

Area of Science:

• Acoustics
• Materials Science
• Aerospace Engineering

Background:

• Electric Vertical Take-Off and Landing (eVTOL) aircraft promise transformative future mobility.
• Ducted fans are key eVTOL propulsion systems, but their noise is a significant challenge.
• Acoustic metamaterial liners are crucial for mitigating eVTOL noise, ensuring public acceptance and regulatory compliance.

Purpose of the Study:

• To address the challenge of selecting the most suitable acoustic metamaterial for specific eVTOL applications.
• To develop a universally applicable filtering concept for evaluating metamaterial performance in noise reduction.
• To analyze and classify existing acoustic metamaterials for noise control in eVTOLs.

Main Methods:

• An extensive database of acoustic metamaterials was compiled and classified into subgroups.
• Metamaterials were designed, fabricated, and their acoustic characteristics assessed through experimental and numerical methods.
• A filtering matrix and a scoring system were developed to evaluate metamaterial applicability.

Main Results:

• A comprehensive overview of acoustic passive metamaterials and their noise reduction efficiencies was presented.
• The study demonstrated a method for scoring and ranking metamaterials based on their suitability for specific applications.
• The filtering concept was successfully illustrated using ducted fans and eVTOL cabin noise scenarios.

Conclusions:

• The developed filtering concept provides a systematic approach to selecting optimal acoustic metamaterials for eVTOL noise reduction.
• This methodology facilitates the application of advanced metamaterials to meet stringent noise regulations and enhance passenger experience.
• The research contributes to the advancement of quieter and more publicly acceptable eVTOL technology.