Aerodynamic Characteristic Analysis of Multi-Rotors Using a Modified Free-Wake Method

Lee, Jaewon; Yee, Kwanjung; Oh, Se-Joon

doi:10.2322/tjsass.52.168

Cited by 23 publications

(4 citation statements)

References 13 publications

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“…Bohorquez and Hein [4][5][6] contributed through hover performance tests, Kunz and Rubio [7,8] through design and analysis, Lakshminarayan, Schroeder through CFD study [9][10][11][12]. On the multirotor side, there are some experimental studies by Radhakrishnan [13] and Ramasamy [14], computational studies by Griffiths [15], Gupta [16], Lee [17], Rajagopalan [18], and Yoon [19]. There have been a couple of aerodynamics studies on quadrotors as well in recent past.…”

Section: Introductionmentioning

confidence: 99%

Multirotor Drone Aerodynamic Interaction Investigation

Shukla

Komerath

2018

Drones

118

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Aerodynamic interactions between rotors are important factors affecting the performance of in-plane multirotor Unmanned Air Vehicles (UAVs) or drones, which are the majority of small size UAVs (or mini-drones). Optimal design requires knowledge of the flow features. The low Reynolds number of many UAV rotors raises the question of how these features differ from those expected by traditional analytical methods for rotorcraft. Aerodynamics of a set of side-by-side rotors in hover over a range of rotor separation and Reynolds number is studied using high-speed Stereo Particle Image Velocimetry (SPIV) and performance measurements. The instantaneous and time-averaged SPIV data presented here indicate an increase in inter-rotor wake interactions with decrease in rotor spacing and Reynolds number. A dip in rotor efficiency at small rotor spacing at low Reynolds number is observed through thrust and torque measurements. The basic components of in-plane multirotor wake and velocity profiles are identified and discussed to help generalize the findings to a wide range of drones. However, the data provide confidence in traditional analysis tools, with small modifications.

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Section: Introductionmentioning

confidence: 99%

Multirotor Drone Aerodynamic Interaction Investigation

Shukla

Komerath

2018

Drones

118

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“…Although VLM is a useful tool for analyzing the aerodynamics of many rotorcraft configurations, it is not suitable for simulating flow-field over structures like fuselage or empennage. Engineers usually use the source-doublet panel method (also known as the panel method) to evaluate the aerodynamic performance of complex planforms [41,50,[89][90][91].…”

Section: Source-doublet Panel Methodsmentioning

confidence: 99%

Review of vortex methods for rotor aerodynamics and wake dynamics

et al. 2022

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Electric vertical take-off and landing (eVTOL) aircraft with multiple lifting rotors or prop-rotors have received significant attention in recent years due to their great potential for next-generation urban air mobility (UAM). Numerical models have been developed and validated as predictive tools to analyze rotor aerodynamics and wake dynamics. Among various numerical approaches, the vortex method is one of the most suitable because it can provide accurate solutions with an affordable computational cost and can represent vorticity fields downstream without numerical dissipation error. This paper presents a brief review of the progress of vortex methods, along with their principles, advantages, and shortcomings. Applications of the vortex methods for modeling the rotor aerodynamics and wake dynamics are also described. However, the vortex methods suffer from the problem that it cannot deal with the nonlinear aerodynamic characteristics associated with the viscous effects and the flow behaviors in the post-stall regime. To overcome the intrinsic drawbacks of the vortex methods, recent progress in a numerical method proposed by the authors is introduced, and model validation against experimental data is discussed in detail. The validation works show that nonlinear vortex lattice method (NVLM) coupled with vortex particle method (VPM) can predict the unsteady aerodynamic forces and complex evolution of the rotor wake.

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“…One possible simplification is the virtual blade model, in which the rotor is replaced by an equivalent rotor disk on which the velocity and/or pressure are specified as source terms with values obtained from transient CFD or measurement. 10,13 Lee et al 14 showed that time-marching free-wake models can be used for multicopter systems. Teske et al 15 developed CHARM, a self-contained rotor/wake/body computational analysis that models rotorcraft blade aerodynamics and dynamics in hover and forward flight, and Teske et al 15 showed that this approach can be used for some types of multicopters.…”

Section: Rotor Wake Modellingmentioning

confidence: 99%

Evaluation of the pattern of spray released from a moving multicopter

Chyrva

Jermy

Strand

et al. 2022

Pest Management Science

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BACKGROUND Multicopters are used for releasing particulates seeds, fertilizer and spray. Their low cost and high manoeuvrability make them attractive for spraying in steep terrain and areas where overspray is undesirable. This article describes a model of multicopter wake and its influence on particulate dispersion, which is computationally economical compared to many computational fluid dynamics (CFD) approaches, yet retains reasonable accuracy. RESULTS A model was successfully implemented in OpenFOAM. It features source terms for the rotor wash, Lagrangian particle tracking, an evaporation model, and a porous medium approach to model the effect of the ground vegetation. Predictions were validated against the field tests of Richardson et al. which used a DJI Agras MG‐1 multicopter in three different flights with airspeeds of 3.2–4.9 m s−1, ground speeds of 2.1–2.9 m s−1 and cross‐wind speeds of 0.04–2.2 m s−1. The effective swath width (30% line separation) was predicted to within one standard deviation. Sensitivity to a rotor rotational speed, flight height, flight velocity, multicopter roll and yaw angles, surface roughness length, plant height and leaf density was checked. CONCLUSION In all flight trials, the modelled swath was closest to the experimentally obtained swath when the surface roughness of the fetch was equal to 0.5 m (bushes) and the rotational speed of all rotors was equal to 2475 rpm with 0.75R (0.2 m) tall plant canopy (grass) introduced to the model. The model showed acceptable validity for flight velocities of ≤2.8–5 m s−1 when flight parameters can be approximately estimated. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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Aerodynamic Characteristic Analysis of Multi-Rotors Using a Modified Free-Wake Method

Cited by 23 publications

References 13 publications

Multirotor Drone Aerodynamic Interaction Investigation

Multirotor Drone Aerodynamic Interaction Investigation

Review of vortex methods for rotor aerodynamics and wake dynamics

Evaluation of the pattern of spray released from a moving multicopter

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