Resilient and Scalable Quasicrystal Coatings for Quiet and Efficient Urban Air Mobility

With the rapid increase in planning and designing of Urban Air Mobility (UAM), one of the major concerns is noise pollution. Aviation noise from UAMs result in different broadbands of noise that can be very loud to the surrounding community. This is a challenge to introduce and maintain a network of urban air transportation at lower altitudes as a part of daily life. Phononic crystal is a functional acoustic material that has excellent potential in the practical engineering of noise reduction. Optimizing the microscale texturing in selected locations of a UAM vehicle is challenging due to the different physics involved in the noise absorption and decomposition within the micro patterns. We performed exploratory experiments using incompressible and transonic turbulent jet flow on cylindrical bodies coated with periodically arranged micro-structures, classified as low and high strength fibers. Preliminary results show a 2-4 dB of overall noise reduction in the case of high strength fibers compared to the base cylinder for a low-pass filter. The surface modification enabled a band gap that generated substantial attenuation of sound transmission. Various canonical and geometry-specific flow diagnostics measurements are underway to inform an optimized process.