8 TH EUROPEAN CONFERENCE FOR AERONAUTICS AND AEROSPACE SCIENCES (EUCASS), JULY 2019 Paper number 359 Computational Analysis of Urban Air Mobility Vehicles Patricia Ventura Diaz * and Seokkwan Yoon † NASA Ames Research Center Moffett Field, California, 94035, USA Abstract High-fidelity computational fluid dynamics simulations of multi-rotor urban air mobility vehicles have been carried out. The capacity for vertical lift, together with the great maneuverability, make multi- rotor vehicles an excellent choice for air taxi operations. The three-dimensional unsteady Navier-Stokes equations are solved on overset grids using high-order accurate schemes, dual-time stepping, and a hybrid turbulence model using NASA’s code Overflow. The flow solver has been loosely coupled with a rotorcraft comprehensive analysis code. The vehicles studied consist of small to medium sized drones, and bigger vehicles for future urban air mobility applications. The concept vehicles are intended to focus and guide NASA research activities in support of aircraft development for emerging aviation markets, in particular vertical take-off and landing air taxi operations. Nomenclature a Fluid speed of sound A Rotor disk area, πR 2 c Local rotor blade chord length C ′ Sectional chord force c tip Rotor blade tip chord length C Q Torque coefficient, Q ρ(ΩR) 2 RA C T Thrust coefficient, T ρ(ΩR) 2 A M ′ Sectional blade pitching moment M Mach number, V a M tip Mach number at the blade tip, ΩR a M 2 c c Sectional chord force coefficient, C ′ 1 2 ρa 2 c M 2 c m Sectional pitching moment coefficient, M ′ 1 2 ρa 2 c 2 M 2 c n Sectional normal force coefficient, N ′ 1 2 ρa 2 c N ′ Sectional blade normal force r Radial position R Rotor radius Re Reynolds number, VL ref ν Re tip Reynolds number at the blade tip, ΩRc tip ν V ∞ Freestream velocity y + Non-dimensional viscous wall spacing α Angle of attack, AoA δ Boundary layer thickness Δ Grid spacing µ Advance ratio, V ∞ cos(α) ΩR ν Fluid kinematic viscosity ρ Fluid density Ω Rotor rotational speed * Science & Technology Corporation. † NASA Advanced Supercomputing Division. This paper is a work of the U.S. Government and is not subject to copyright protection in the U.S.. DOI: 10.13009/EUCASS2019-359