NASA@SC18

Aeronautics

Towards Urban Air Mobility: The Side-By-Side Air Taxi

Overview

Increased urbanization is pushing our cities’ transportation to its limits, costing valuable time and money. What if we could use the third dimension to move around town? Imagine a sky with delivery drones, urban air taxis, and shared flying vehicles. No, this is not a dream. This is Urban Air Mobility (UAM)—the new era in air transportation that NASA is working on right now.

UAM vehicles are envisioned to be autonomous and use electric or hybrid propulsion to transport a small number of passengers from one point in a city to another in a short time, avoiding all ground traffic; and to have the capacity for vertical take-off and landing (VTOL), eliminating the need for large-scale infrastructure such as long runways. Their rechargeable batteries promise a greener future for aviation. NASA has proposed multiple conceptual designs for UAM that can be used as a common reference in industry and academia.

Project Details

In this work, NASA’s side-by-side, intermeshing rotor air taxi concept is simulated using high-fidelity computational fluid dynamics (CFD) methods. An intermeshing rotorcraft offers the advantage of being more compact while being able to generate the same or higher thrust than a side-by-side helicopter without overlapping rotors.

The surface of the rotorcraft, and surrounding air, are modeled using hundreds of millions of grid points with overset volume grids. The flow is then resolved with NASA’s high-order accurate Navier-Stokes CFD solver, OVERFLOW.

Results and Impact

After first generating the overset grids and simulating the flow for different flight conditions, we then calculate the performance of the rotorcraft configurations. High-resolution visualizations help researchers understand the complex rotor flow interactions. In addition, results from high-fidelity simulations can be used to calibrate and validate low-fidelity design tools.

Why HPC Matters

In order to accurately predict the performance of the rotorcraft, the fluid equations are solved on grids comprising hundreds of millions of grid points. In addition, the rotating grids for the blades make the problem unsteady. The rotor interactions are captured thanks to OVERFLOW. Only with the most powerful supercomputers can such complex problems be solved in just a few days.

The simulations were carried out on NASA’s Pleiades and Electra supercomputers at the NASA Advanced Supercomputing (NAS) facility, using between 1,000 to 2,000 Intel Xeon Broadwell and Skylake processors.

What's Next

The side-by-side air taxi is one of many NASA conceptual designs for UAM. Other new configurations are being explored and simulated with high-fidelity CFD.

More Information

Patricia Ventura Diaz, NASA Ames Research Center
patricia.venturadiaz@nasa.gov
Seokkwan Yoon, NASA Ames Research Center
s.yoon@nasa.gov