Aeroacoustics and Vibration Analysis of Multirotor eVTOL for Sustainable Urban Air Mobility (UAM)

Urban air mobility (UAM) is gaining popularity, driving advancements in electric vertical takeoff and landing (eVTOL) aircraft. These advancements are significant in metropolitan areas, where it is necessary to mitigate vibration and noise. This letter explores the noise and vibrational study of eVTOLs, aiming to make UAM more eco-friendly and widely accepted. It focuses on the distinct noise patterns of multirotor aircraft across various flight phases from static to dynamic tests. The proposed eVTOL UAM prototype features a lightweight carbon-fiber-reinforced structure with a total all-up weight of 110 kg, including a payload capacity of 50 kg. The study uses a 3-D approach to analyze the different vibrational and acoustic behaviors of eVTOLs in these scenarios. It delves into how noise is created and spread, particularly from rotor blades, emphasizing tonal and broadband noise. The research employs experimental analysis involving accelerometers, microphones, and tachometers for detailed tracking of vibrations and noise levels within the aircraft's structure. The noise spectrum data show its main features; the dominant noise levels were observed in low frequencies up to 800 Hz, between 6 and 7 kHz, and around 9 kHz. In addition, the vibrational analysis reveals that the dominant natural frequency is observed to be at 200 Hz. This analysis leads to insights toward vibration reduction strategies through structural improvements and damping technologies.