국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	Development and Validation of an Interactive Liner Design and Impedance Modeling Tool
저자	Howerton, Brian M.;; Jones, Michael G.;; Buckley, James L.
Keyword	ACOUSTIC IMPEDANCE;; ACOUSTIC PROPERTIES;; BROADBAND;; FREQUENCY RANGES;; GRAPHICAL USER INTERFACE;; LININGS;; MATHEMATICAL MODELS;; NOISE REDUCTION;; RESONATORS;; SOUND TRANSMISSION;; SURFACE PROPERTIES;; TRANSMISSION LINES
URL	http://hdl.handle.net/2060/20120010351
보고서번호	NF1676L13780
발행년도	2012
출처	NTRS (NASA Technical Report Server)
ABSTRACT	The Interactive Liner Impedance Analysis and Design (ILIAD) tool is a LabVIEW-based software package used to design the composite surface impedance of a series of small-diameter quarter-wavelength resonators incorporating variable depth and sharp bends. Such structures are useful for packaging broadband acoustic liners into constrained spaces for turbofan engine noise control applications. ILIAD s graphical user interface allows the acoustic channel geometry to be drawn in the liner volume while the surface impedance and absorption coefficient calculations are updated in real-time. A one-dimensional transmission line model serves as the basis for the impedance calculation and can be applied to many liner configurations. Experimentally, tonal and broadband acoustic data were acquired in the NASA Langley Normal Incidence Tube over the frequency range of 500 to 3000 Hz at 120 and 140 dB SPL. Normalized impedance spectra were measured using the Two-Microphone Method for the various combinations of channel configurations. Comparisons between the computed and measured impedances show excellent agreement for broadband liners comprised of multiple, variable-depth channels. The software can be used to design arrays of resonators that can be packaged into complex geometries heretofore unsuitable for effective acoustic treatment.