국내 최대 기계 및 로봇 연구정보

공학설계D/B

공학설계D/B 게시판 내용
Volume Title	Vibration and Acoustic Fatigue
Volume No	Loading actions (near-field jet, buzz-saw noise due to fan, turbulent boundary layer) and Damping (estimation in laminated plates, use of damping treatments).
DATA Title	Computer-based estimation procedure for near-field single-stream jet noise.
DATA Item	99006
KEYWORD	acoustic, engine, field, jet, level, loading, near, noise, pressure, program, sound, turbo
ISBN	1 86246 074 4
ABSTRACT	ESDU 99006 introduces a program (ESDUpac A9906) for estimating near-field noise spectra by interpolating within or extrapolating a database. The variables considered make the procedure particularly applicable to estimating noise from a single-stream jet. Three comprehensive databases are provided, but ESDUpac C9906 may be run to create a new database using the user뭩 data that could include installation and flight effects as well as other noise components (such as combustion noise), or the user may supplement the database with additional data. One database uses data from ESDU 72002 which relates to full-scale jets while the other two result from model tests, for a subsonic jet in one case and a supersonic jet in the other. If a non-axisymmetric jet is used, all measurements in the database, and predictions from it, must apply in the same plane. The method uses a least-squares fitting procedure to estimate noise spectra for the required jet operating condition at nine locations in the database closest to the location of interest. A second fitting procedure for distance is then used to calculate the noise spectrum at the required position. Output is in one-third octave band levels or in spectrum values of dB/Hz (or pascal/Hz). The estimation process using ESDUpac A9906 is described and illustrated with practical worked examples and requires the creation of an input file, the construction of which ESDUpac B9906 facilitates. The programs are provided on disc in the software volume. To facilitate data transfer between programs in the Aircraft Noise Series a standardised format for a common file has been formulated and is described.