THE EFFECTIVENNESS OF SOME PRACTICAL METHODS OF LOWERING THE BACKGROUND ACOUSTIC NOISE, PRODUCED BY THE ENGINE TEST BENCH TECHNOLOGICAL EQUIPMENT

When conducting acoustic researches and finishing works on combustion engines specialized technological equipment and tools mounted mainly in anechoic chambers are used. In order to ensure the high quality and objectivity of the research results of the sound fields produced by the research object it is crucial to achieve a sufficiently low parasitic background noise produced by technological equipment and tools of an engine test bench. The source of a high background noise re-emited to the anechoic chambers interior is structural vibrations of the solid objects of load carrying and flatsheet box-type structures of the bench. The article considers tested technical methods of improving vibroacoustics of load carrying and envelope structures of the engine test bench, which is in startup, commissioning and preliminary operation phase in the research center of a car manufacturer. Therewith there was a requirement to prevent any fundamental changes of the bench original basic construction, in order to minimize potential material and financial expenses for its reengineering process. Tested design solutions allow to reduce the level of parasitic noise disturbances, produced directly by the bench equipment in an anechoic chamber, up to 12 dBA.