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Prediction of BVI Noise for an Active Twist Rotor Using a Loosely Coupled CFD/CSD Method and Comparison to Experimental DataNumerical predictions of the acoustic characteristics of an Active Twist Rotor (ATR), using two methods to compute the rotor blade aerodynamics and elastic blade motion are compared to experimental data from a wind tunnel test in the NASA Langley Transonic Dynamics Tunnel (TDT) in 2000. The first method, a loosely coupled iterative method, utilizes the Computational Fluid Dynamics (CFD) code OVERFLOW 2 and the Computational Structural Dynamics (CSD) code CAMRAD II. The second method utilizes the CAMRAD II free-wake model only. The harmonic active-twist control to the main rotor blade system is identified with three parameters - harmonic actuation frequency, actuation amplitude, and control phase angle. The resulting aerodynamics and blade motion data from the two methods are then used in the acoustics code PSU-WOPWOP to predict acoustic pressure on a spherical array of equally spaced observers surrounding the rotor. This spherical distribution of pressure is used to compute the sound power level representing baseline and actuated conditions. Sound power levels for three categories of noise are defined as - blade-vortex interaction sound power level (BVIPWL), low frequency sound power level (LFPWL), and overall sound power level, OAPWL. Comparisons with measured data indicate the CFD/CSD analysis successfully captures the trends in sound power levels and the effects of active-twist control at advance ratios of 0.14 and 0.17. The free-wake model predictions show inconsistent sound power levels relative to the trends in the experimental and CFD data. This paper presents the first ever comparison between CFD/CSD acoustic predictions for an active-twist rotor and experimental measurements.
Document ID
20120009834
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Fogarty, David E.
(National Inst. of Aerospace Associates Hampton, VA, United States)
Wilbur, Matthew L.
(Army Research Lab. Hampton, VA, United States)
Sekula, Martin K.
(Army Research Lab. Hampton, VA, United States)
Boyd, David Douglas, Jr.
(Army Research Lab. Hampton, VA, United States)
Date Acquired
August 25, 2013
Publication Date
May 1, 2012
Subject Category
Acoustics
Report/Patent Number
NF1676L-14452
Meeting Information
Meeting: American Helicopter Society 68th Annual Forum and Technology Display
Location: Fort Worth, TX
Country: United States
Start Date: May 1, 2012
End Date: May 3, 2012
Funding Number(s)
WBS: WBS 877868.02.07.07.03.02.01
Distribution Limits
Public
Copyright
Other

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