Engine Noise Source Identification Based On Optimized Random Array

The laws and regulations of the current vehicle noise become more and morestrict, and the engine noise is one of the main factors affecting the automotive NVHperformance, so there is an urgent need for engine noise source identification andnoise control.This paper described the various types of engine noise and its causes, andproposed some appropriate measures to improve the different noise. Outlined thefundamental principles of traditional engine noise source identification methods andmodern methods of noise source identification, and introduced the advantages anddisadvantages of these methods, made an in-depth study of the principles andparameters of the beam-forming technology. Acoustic array of different waysespecially optimized random acoustic array were described, focusing on the wheelarray and pizza array belong to the optical random acoustic arrays.Used a method of combing simulation prediction and experimental measurementto analyze for the side cover structural noise of an engine, measured engine left shellvibration acceleration signal with LMS Test. Lab, which was imported in Hypermeshas an excitation to make finite element analysis of the left shell, extracted surfacevibration velocity frequency spectrum as the engine left shell noise radiationboundary conditions, used the LMS Virtual. Lab to do acoustic simulation, analyzedthe simulation results of the noise precision. Beamforming technology was appliedthrough the3560D data front-end of Brüel&Kj r company to have a noise test forthe left side cover, compared with the simulation and verified the results, these twosound power curves were consistent. Made improvements in the left shell structure,then had a noise test on the improved left cover; the improved effect was provedsignificantly. It is of greater reference significance to predict side coverstructure-borne noise and reduce the noise of the entire engine.Located noise sources of the engine with Beamforming technology. Analyzed thepeak signals and contours of each section of the frequency, which determined thedominant noise source was probably at the sprocket cover and flywheel cover.Through order analysis and the elimination method, finally confirmed these twocomponents were the main noise source of the engine. Improve the two componentsby modal analysis and topology optimization. Made an experiment on the improvedmachine and analyzed the collected signal again and verified the results. Compare the power spectra of the original engine and the improved engine, and the sound power oflevel had reduced0.7dB after the improvement, provides a certain reference for thestudy of engine noise reduction.