![]() ![]() In a nutshell, they discovered that the interactions between rotor wakes in the standard SUI Endurance configuration-with its four overmount rotors-reduce the performance of the rear rotors in forward flight. "In addition," said Ventura Diaz, "the customized images and movies that the NAS Division’s scientific visualization experts created from our simulations are critical to our improved understanding of the complex flow interactions of these vehicles." "NASA’s high-end computing resources were absolutely essential for obtaining our first-of-a-kind results," said Yoon. Ventura Diaz generated complex overset grid systems with hundreds of millions of grid points for each geometry, and ran dozens of simulations on thousands of Intel Xeon (Broadwell) processors on the Pleiades and Electra supercomputers at the NAS facility. Using NASA’s OVERFLOW CFD solver and its Chimera Grid Tools grid-generation software, NAS aerospace engineer Patricia Ventura Diaz spent months painstakingly modeling the surface grids of numerous configuration geometries for three UAVs: the DJI Phantom 3 quadcopter, which has a symmetrical X-shaped airframe with four propellers mounted over the airframe the Straight Up Imaging (SUI) Endurance quadcopter with an elongated airplane-shaped airframe and the Elytron 4S UAV concept for future UAM, which has a joined wing and a smaller, central tilt-wing on which the propellers are mounted. Modeling, Visualization Lead to Discovery "The simulation results show that our hybrid configuration reduces drag, increases forward thrust by more than 50% over the standard configuration, and results in a more aerodynamically efficient vehicle," Yoon continued. "Our simulations produced the highest quality results ever seen in multi-rotor aircraft, allowing us to more deeply understand the complex flow interactions between the UAV rotors and to reveal issues in each design." "This is the first time anyone has done higher-order accurate numerical simulations for urban air mobility vehicles," said Seokkwan Yoon, computational physics branch chief in the NAS Division. What they learned led them to develop a new hybrid quadcopter configuration that will result in a vehicle that flies faster, quieter, and longer. Our simulations produced the highest quality results ever seen in multi-rotor aircraft, allowing us to more deeply understand the complex flow interactions between the UAV rotors and to reveal issues in each design.Īpplying their deep knowledge and experience in using computational fluid dynamics (CFD) to improve the safety and performance of spacecraft, airplanes, and helicopters, NAS Division aerodynamics experts ran high-fidelity CFD simulations to study the performance of three multi-rotor UAV designs, with numerous variations of each. ![]() ![]() Which is why a recent discovery by a team of researchers using high-performance computers at the NASA Advanced Supercomputing (NAS) Division, at NASA’s Ames Research Center, will have far-reaching impacts for designers and manufacturers of future multirotor UAVs and UAM vehicles. Love ’em or hate ’em, drones are here to stay. These are some of the common complaints and safety issues with drones-or Unmanned Aerial Vehicles (UAVs). On the other hand: that annoying buzz droning on and on when you’re trying to commune with nature. Timothy Sandstrom, NASA/Amesĭrones provide many benefits for us earth-bound creatures: disaster relief, beautiful aerial photographs and videos, speedy package delivery, wildlife research, storm tracking and hurricane prediction-and someday, planetary exploration and Urban Air Mobility (UAM) for human transportation in cities. The hybrid design reduces the rotor wake interactions and yields much better performance. The difference in pressure is what generates thrust to fly the drone. If you look closely, you can see that the upper surfaces of the blades are blue (lower pressure), and the lower surfaces are red (higher pressure). The video then shows the vortex wake using the Q-criterion isosurfaces. ![]() The video starts with NASA’s novel hybrid design modification from the original configuration, where the front rotors have been undermounted and the back rotors are kept overmounted. Video from a computational fluid dynamics simulation of the Straight Up Imaging (SUI) Endurance quadcopter hybrid design in forward flight. ![]()
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