Computational Analysis of Multi-Rotor Flows

Yoon, Seokkwan; Lee, Henry; Pulliam, Thomas H.

doi:10.2514/6.2016-0812

Cited by 109 publications

(70 citation statements)

References 7 publications

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“…3, though the separation distance was shortened by a factor of 10, the measured thrust coefficient for the twin-rotor cases was found to drop by less than 2%, which suggests that the generated mean thrust is independent of the separation distance. Similar results were also reported by Yoon et al [7], who performed a computational study on the aerodynamic interactions of multirotor flows. While the separation distance had limit effect on the thrust coefficient of rotor, the force fluctuations (i.e., thrust standard deviation) were found to increase dramatically as the separation distance becomes smaller.…”

Section: Test Model and Experimental Setupssupporting

confidence: 89%

“…Very few studies can be found in literatures that examined the rotor-torotor interactions on the aerodynamic and aeroacoustic performance of UAVs. Except for Yoon et al [7], they computationally analyzed the aerodynamics performance of multi-rotor flows in a quadcopter, and found that the rotor interaction has significant effects on the vertical forces of quadrotor systems in hover motion. And Intaratep et al [8], who experimentally measured the acoustics level of Phantom II at static thrust conditions, found that there is a dramatically increase in acoustic broadband noise if increased the rotors from 2 to 4.…”

mentioning

confidence: 99%

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An Experimental Investigation on Rotor-to-Rotor Interactions of Small UAV Propellers

Zhou

Ning

et al. 2017

35th AIAA Applied Aerodynamics Conference

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In the present study, an experimental investigation was performed to study the effects of rotor-to-rotor interactions on the aerodynamic and aeroacoustic performances of small UAVs. It was found that, while the thrust coefficients of rotor were independent of the separation distance, the thrust fluctuations were found to increase dramatically as the separation distance decreased. An enhancement of ~ 250% was confirmed for the twin-rotor case (i.e., L= 0.05D) in comparison with that of the single rotor case, which is believed to be caused by the complex flow interactions within rotors as revealed by the detailed PIV and Stereoscopic PIV measurements. Reducing the separation distance not only intensified the force fluctuations, but also increased the aeroacoustic noise level of the baseline case. Comparing to the L = 1.0D case, a maximum enhancement of ~3 dB in aeroacoustic noise was recorded for the L = 0.05D case, which is caused by the severely thrust fluctuations and turbulent flow interactions within rotors.

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Section: Test Model and Experimental Setupssupporting

confidence: 89%

mentioning

confidence: 99%

An Experimental Investigation on Rotor-to-Rotor Interactions of Small UAV Propellers

Zhou

Ning

et al. 2017

35th AIAA Applied Aerodynamics Conference

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“…The impact of rotor turbulence with respect to detecting trace gas concentrations with sensors onboard UASs is relatively unexplored. A handful of publications present some computational fluid dynamic (CFD) analysis in a general context of mapping quadrotor downwash [29][30][31], but there are limited publications that include a CFD analysis for sensor placement [32]. Furthermore, the computational resources are not currently available to run detailed simulations that include the effect on local gas concentrations, thus the analysis of how gas concentrations are affected by UAS rotor turbulence is still something that needs to be studied.…”

Section: Sensors For Trace Gasesmentioning

confidence: 99%

Unmanned Aerial Systems for Monitoring Trace Tropospheric Gases

Schuyler

Guzmán

2017

Atmosphere

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Abstract:The emission of greenhouse gases (GHGs) has changed the composition of the atmosphere during the Anthropocene. Accurately documenting the sources and magnitude of GHGs emission is an important undertaking for discriminating the contributions of different processes to radiative forcing. Currently there is no mobile platform that is able to quantify trace gases at altitudes <100 m above ground level that can achieve spatiotemporal resolution on the order of meters and seconds. Unmanned aerial systems (UASs) can be deployed on-site in minutes and can support the payloads necessary to quantify trace gases. Therefore, current efforts combine the use of UASs available on the civilian market with inexpensively designed analytical systems for monitoring atmospheric trace gases. In this context, this perspective introduces the most relevant classes of UASs available and evaluates their suitability to operate three kinds of detectors for atmospheric trace gases. The three subsets of UASs discussed are: (1) micro aerial vehicles (MAVs); (2) vertical take-off and landing (VTOL); and, (3) low-altitude short endurance (LASE) systems. The trace gas detectors evaluated are first the vertical cavity surface emitting laser (VCSEL), which is an infrared laser-absorption technique; second two types of metal-oxide semiconductor sensors; and, third a modified catalytic type sensor. UASs with wingspans under 3 m that can carry up to 5 kg a few hundred meters high for at least 30 min provide the best cost and convenience compromise for sensors deployment. Future efforts should be focused on the calibration and validation of lightweight analytical systems mounted on UASs for quantifying trace atmospheric gases. In conclusion, UASs offer new and exciting opportunities to study atmospheric composition and its effect on weather patterns and climate change.

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“…This is usually accomplished by using the overset or Chimera grid technique. Some notable works include those of Yoon et al [5], Potsdam and Strawn [6], and Schwarz [7]. Although this approach has high fidelity, it is time consuming.…”

Section: Introductionmentioning

confidence: 99%

Numerical Calculations on the Unsteady Aerodynamic Force of the Tilt-Rotor Aircraft in Conversion Mode

Chen

2019

International Journal of Aerospace Engineering

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A computational method is developed in order to predict the unsteady aerodynamic characteristics of the tilt-rotor aircraft in conversion mode. In this approach, the rotor is modeled as an actuator disk so that the effect of individual blades can be ignored. A novel predictor-corrector-based dynamic mesh method is presented for dealing with extremely large mesh deformation during a conversion process. The dual time-stepping approach and the finite volume scheme are applied to solve the unsteady N-S equation. A parallel algorithm is utilized in this work to improve the computational efficiency. By using the present method, quantitative and qualitative comparisons are made between the aerodynamic coefficients obtained in the quasi-steady fixed conversion mode and the time-accurate continuous transition flight condition. Both two-dimensional (2D) and three-dimensional (3D) computations are carried out. The influence of the tilt modes and the tilt period time on the unsteady aerodynamic forces are also studied. Numerical results demonstrate that the developed method is effective in simulating the aerodynamic characteristics of the tilt-rotor aircraft in conversion mode.

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Computational Analysis of Multi-Rotor Flows

Cited by 109 publications

References 7 publications

An Experimental Investigation on Rotor-to-Rotor Interactions of Small UAV Propellers

An Experimental Investigation on Rotor-to-Rotor Interactions of Small UAV Propellers

Unmanned Aerial Systems for Monitoring Trace Tropospheric Gases

Numerical Calculations on the Unsteady Aerodynamic Force of the Tilt-Rotor Aircraft in Conversion Mode

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