NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Acoustic Characterization and Prediction of Representative, Small-Scale Rotary-Wing Unmanned Aircraft System ComponentsIn this study, hover performance and acoustic measurements are taken on two different isolated rotors representative of small-scale rotary-wing unmanned aircraft systems (UAS) for a range of rotation rates. Each rotor system consists of two fixed-pitch blades powered by a brushless motor. For nearly the same thrust condition, significant differences in overall sound pressure level (OASPL), up to 8 dB, and directivity were observed between the two rotor systems. Differences are shown to be in part attributed to different rotor tip speeds, along with increased broadband and motor noise levels. In addition to acoustic measurements, aeroacoustic predictions were implemented in order to better understand the noise content of the rotor systems. Numerical aerodynamic predictions were computed using the unsteady Reynoldsaveraged Navier Stokes code OVERFLOW2 on one of the isolated rotors, while analytical predictions were computed using the Propeller Analysis System of the Aircraft NOise Prediction Program (ANOPP-PAS) on the two rotor configurations. Preliminary semi-empirical frequency domain broadband noise predictions were also carried out based on airfoil self-noise theory in a rotational reference frame. The prediction techniques further supported trends identified in the experimental data analysis. The brushless motors were observed to be important noise contributors and warrant further investigation. It is believed that UAS acoustic prediction capabilities must consider both rotor and motor components as part of a combined noise-generating system.
Document ID
20160009054
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Zawodny, Nikolas S.
(NASA Langley Research Center Hampton, VA, United States)
Boyd, D. Douglas, Jr.
(NASA Langley Research Center Hampton, VA, United States)
Burley, Casey L.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
July 15, 2016
Publication Date
May 17, 2016
Subject Category
Aerodynamics
Acoustics
Report/Patent Number
NF1676L-22587
Meeting Information
Meeting: American Helicopter Society (AHS) Annual Forum
Location: West Palm Beach, FL
Country: United States
Start Date: May 17, 2016
End Date: May 19, 2016
Sponsors: American Helicopter Society, Inc.
Funding Number(s)
WBS: WBS 533127.02.04.07.01
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
No Preview Available