Доступ предоставлен для: Guest
TSFP DL Home Архив Исполнительный Комитет

CORRELATIONS OF NEAR- AND FAR-FIELD ACOUSTIC DATA IN A HIGH-SPEED JET

Jacques Lewalle
Department of Mechanical and Aerospace Engineering Syracuse University Syracuse, New York 13244, USA

Kerwin R. Low
Department of Mechanical Engineering & Aerospace Engineering, Syracuse University, 149 Link Hall, Syracuse, New York,13244-1240, U.S.A.

Mark N. Glauser
Department of Mechanical and Aerospace Engineering Syracuse University Syracuse, NY 13244, USA

Zachary P. Berger
Department of Mechanical and Aerospace Engineering Syracuse University Syracuse, New York 13244, USA

Аннотация

The cross-correlations of near- and far-field pressure in a M=0.6 cold jet are oscillatory, which implies some phase-locking. A simple model and synthetic signals show that the locking may be related to the steep attenuation with distance from the near-field sensors. In the near-field, wavelet-based nonlinear filtering separates fluctuations that are recognizable at x/D = 3 and 6 (`matched') from the others ('residue'). This decomposition yields distinct signatures in the cross-correlations. The corresponding time lags and frequencies in the cross-correlations point to several categories of sources and their locations. The interpretation is consistent with the eddy pairing or breakdown (i.e. loss of identity) as the sources of noise for short lags, but the longer time lags require another explanation.