A Study on Circulation Strength Decay Over Time of Quadrotor Wake Using Large Eddy Simulation

AIAA SCITECH 2022 Forum

2022

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With the increase interest in utilizing multirotor UAS in very low altitude airspace, the safety aspect associated with higher UAS density gains importance. One of the safety consideration is the separation requirements for UAS sharing the airspace, which consists of two major components: wake-based and CNS performance-based. To evaluate the wake-based separation requirements, the wake-field produced by the leading UAS and the resulting encounter response by the follower UAS must be obtained. While previous studies on aircraft wake vortex evolution showed that the fuselage wake have small impact on the overall wake vortex strength and structures, the more distributed lift generation with less distance between the initial formation point of wake vortex to the fuselage could lead to a larger impact. This paper investigates the impact of including multirotor fuselage on simulating the strength and structure of the resulting wake vortex.

Section: Summary and Future Workmentioning

confidence: 98%

Numerical Investigation on Influence of Fuselage on Multirotor Wake Vortex Structures in Forward Flight

AIAA SCITECH 2022 Forum

2022

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“…Similar process was also used in Refs. [32] and [27] to investigate the long-term evolution and impact of fuselage model inclusion, respectively. The simulations were carried out in two parts, the RANS turbulence modeling for near-field wake generation and the LES turbulence modeling for far-field wake generation.…”

Section: Simulation Setupmentioning

confidence: 99%

Comparison of Small Multirotor Wake Vortex of Different Weight Class and Rotor Configurations via Numerical Simulation

AIAA SCITECH 2023 Forum

2023

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Wake hazard is one of the factors affecting the separation requirement for same-track fixedwing aircraft in civil aviation. It could also be a contributing factor for UAS traffic management (UTM) with multirotors, especially with the widespread use of ADS-B like remoteID for UAS that greatly reduces the separation requirements due to communication, navigation, and surveillance (CNS) performance of the aircraft and the airspace. While the wake vortex structure and decay mechanism for fixed-wing aircraft has been well studied over the years, the same dynamics might not be observed in multirotor aircraft due to difference in lift generation mechanism. Additionally, the difference in wake vortex generation from different multirotor configurations were not as well studied. This paper presents the simulation results from two quadrotors (DJI Phantom 3 size, ∼ 1.2 kg, and Inspire 1 size, ∼ 3.5 kg) and one hexarotors (DJI M600 sized, ∼ 15 kg) for a fixed follow distance behind those aircraft.

“…In addition, instead of only inferring the wind effect from the flow results, the simulated wind data can be utilized for UAS flight simulation using software-in-the-loop (SITL) [27,28] to study UAS stability and flight behavior when encountering the flow patterns in the urban wind field. Simulation with SITL was previously used to determine the separation requirement between UAS by examining the flight behavior of UAS when encountering the wake vortex from another UAS [29,30].…”

Section: Summary and Future Workmentioning

confidence: 99%

Simulation of Wind Field in a Building Complex for Evaluation of the Wind Effect Along UAS Flight Path

AIAA AVIATION 2023 Forum

2023

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With the use of Unmanned Aerial Systems (UAS) becoming more common, wind field within urban environments becomes significant, and its impact on UAS flight should be examined to ensure UAS operations can be implemented and managed safely with little to no risk of damages and injuries to the inhabitants and infrastructures. This study presents the wind field within the Biopolis building complex in Singapore from steady-state RANS simulation using OpenFOAM v1912. The wind simulation was done using various inlet wind speeds and directions based on the measurements from a weather station near the building complex. After obtaining the velocity field for the whole area, the wind effect on UAS along a given flight path was inferred from the local wind velocity magnitude and direction along the path. When the general wind heading was aligned with the flight path, the local wind and its impact on the UAS along its path had more gradual and less extreme changes than in other cases where the UAS had to fly by crossing through the wake flow of the buildings. Additionally, for flow cases with the same inlet wind direction but different reference speeds, similarity in their results was observed when the wind velocity magnitude was normalized with respect to the velocity magnitude at the inlet boundary. Contours of the wind Turbulence Kinetic Energy (TKE) from the simulation results show that the areas with higher TKE are located around buildings at the most upstream against the wind, and these areas increase in size and TKE levels with higher wind speed.