Browse Topic: Transportation Systems
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Urban Air Mobility (UAM) aircraft are highly susceptible to turbulent wind disturbances when operating near buildings in complex urban environments. Microscale wind phenomena, combined with the unconventional designs of UAM aircraft, increase the risk of performance deviation, the overall duration, and the cost of flight tests for certification. A way to overcome this would be through simulation-based flight tests. Therefore, this study simulates a UAM aircraft landing vertically behind an isolated tall building, considering four different wind scenarios: no wind, uniform wind fields at low and high spatial resolutions (assumed constant across the airframe), and non-uniform fields with spatially varying velocity profiles at individual rotor hubs. The resultant flight test data are then used to quantify the impact of microscale wind characteristics on landing performance by systematically analyzing the rotor performance, aerodynamics, control response, and trajectory deviation.
Electric vertical takeoff and landing aircraft (eVTOL) have swiftly risen to prominence since the early 2000's due to their potential to serve as a sustainable and scalable improvement in urban air mobility. In edgewise forward flight, these aircraft can experience significant time-varying aerodynamic loads due to being variable RPM vehicles. Their fuselage, booms and auxiliary lifting surfaces are often very lightly damped, lightweight and highly stiff. Thus, multiple bending and torsional modes of vibration can be excited and result in unacceptably high stress levels. Particle impact dampers (PIDs) are an attractive vibration mitigation strategy as they can target more than one mode of vibration. The potential use of a PID to target a bending mode of vibration is experimentally and numerically studied within this work. Experimental forced response analysis shows a 53% attenuation in amplitude of vibrations at the cost of a 5% mass penalty. A reduced order model was developed in order
In the context of developing new rotorcrafts dedicated to Advanced Air Mobility, aeroacoustic simulations of co-axial rotor systems have been conducted using the lattice Boltzmann method with the ProLB code. Eight configurations, spanning from co-rotating rotors to contra-rotating shrouded rotors, were analyzed in stationary conditions through comparisons with experimental data and flow field analysis. This investigation validates our numerical methodology, based on direct noise simulation, and enhances our understanding of noise generation and propagation of such propulsive systems. Our simulations successfully replicate all measured trends in global aerodynamic performance, average noise levels, and noise directivities. Maximum discrepancies were 1.5 N (9%) and 2.1 dB (averaged noise level on the considered microphones). Based on our analysis, the following observations have been made. The open co-rotating rotors is the quietest configuration due to reduced Blade-Vortex Interaction
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