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Interior Noise Predictions in the Preliminary Design of the Large Civil Tiltrotor (LCTR2)
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Author and Affiliation:
Grosveld, Ferdinand W.(Northrop Grumman Corp., Hampton, VA, United States);
Cabell, Randolph H.(NASA Langley Research Center, Hampton, VA, United States);
Boyd, David D.(NASA Langley Research Center, Hampton, VA, United States)
Abstract: A prediction scheme was established to compute sound pressure levels in the interior of a simplified cabin model of the second generation Large Civil Tiltrotor (LCTR2) during cruise conditions, while being excited by turbulent boundary layer flow over the fuselage, or by tiltrotor blade loading and thickness noise. Finite element models of the cabin structure, interior acoustic space, and acoustically absorbent (poro-elastic) materials in the fuselage were generated and combined into a coupled structural-acoustic model. Fluctuating power spectral densities were computed according to the Efimtsov turbulent boundary layer excitation model. Noise associated with the tiltrotor blades was predicted in the time domain as fluctuating surface pressures and converted to power spectral densities at the fuselage skin finite element nodes. A hybrid finite element (FE) approach was used to compute the low frequency acoustic cabin response over the frequency range 6-141 Hz with a 1 Hz bandwidth, and the Statistical Energy Analysis (SEA) approach was used to predict the interior noise for the 125-8000 Hz one-third octave bands.
Publication Date: May 21, 2013
Document ID:
20130013992
(Acquired Jul 19, 2013)
Subject Category: ACOUSTICS
Report/Patent Number: NF1676L-15561
Document Type: Conference Paper
Meeting Information: 69th Annual American Helicopter Society Forum and Technology Display; 21-23 May 2013; Phoenix, AZ; United States
Meeting Sponsor: American Helicopter Society, Inc.; New York, NY, United States
Contract/Grant/Task Num: WBS 380046.02.07.04.01.05
Financial Sponsor: NASA Langley Research Center; Hampton, VA, United States
Organization Source: NASA Langley Research Center; Hampton, VA, United States
Description: 12p; In English; Original contains color illustrations
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution as joint owner in the copyright
NASA Terms: SOUND PRESSURE; TILT ROTOR AIRCRAFT; TURBULENT BOUNDARY LAYER; FUSELAGES; NOISE PREDICTION; ACOUSTIC PROPERTIES; FREQUENCY RESPONSE; STATISTICAL ANALYSIS; FREQUENCY RANGES
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