This paper describes the analyses of automobile transaxle noise under both stationary and non-stationary conditions using the Helmholtz Equation Least Squares (HELS) based near-field acoustic holography method. Analyses are carried out at 1266 and 3500 rpm, respectively, under a steady-state condition, and from 1000 to 6000 rpm run-up conditions. In all these analyses, a custom designed 63 microphone arrays conforming to the contour of the transaxle front and side surfaces are used to acquire the acoustic pressures in the nearfield of the transaxle. These acoustic pressures are taken as input to the HELS codes to reconstruct the entire acoustic field on the transaxle surface, including the surface acoustic pressures, normal surface velocity, and normal acoustic intensity. For the transaxle run-up noise analysis, spectrograms are generated, which are correlated directly to the acoustic pressure, velocity, and surface acoustic intensity distributions on the transaxle surface. These diagrams enable one to correlate specific orders in spectrograms to the 'hot spots' on the source surface directly, and to identify the energy input to the transaxle that produce sound radiation to the exterior region. These three-dimensional acoustic images can provide valuable insight into transaxle noise reduction.
Analysis of transaxle noise using HELS-based near-field acoustic holography
Analyse des Transaxle-Geräusches mit Hilfe der akustischen Nahfeldholographie auf der Basis der Methode der kleinsten Quadrate der Helmholtz-Gleichung
2006
6 Seiten, 7 Bilder, 12 Quellen
Conference paper
English
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