Laermminderungsmassnahmen an einem rueckentragbaren Luftblasgeraet mit einem Zweitakt Verbrennungsmotor

Within this research project a low-noise air-blower was developed, which under maximum power produces a volume-flow of 730 m"3/h and a sound power level of 97 dB(A). Near the operator's ear, a sound power level of 85 dB(A) is not exceeded. Therefore, compared to ordinary blowers with the same volume-flow, this low-noise blower shows a reduced noise-emission of more than 10 dB(A). This noise-reducement was possible through technical advancement of some components. The rotational speed was lowered by more than 1000 min"-"1 without reducing the produced volume - flow. The below listed measures were proceeded: increase of motor-power through tuned intake pressure charging, development of inlet and muffler silencer as Helmholtz resonator, avoidance of sharp edges in the ventilator's inside, enlargement of tongue radius, increase of relation of obstacles in the flow to casing. The accomplished measures can be taken over the production without any kind of restriction. The measures at the driving elements can also be applied to other motor powered gradening equipment. Increased costs arise only at the muffler silencer. (orig.)SIGLEAvailable from TIB Hannover: RN 8908(96-025) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Umwelt, Naturschutz und Reaktorsicherheit, Bonn (Germany)DEGerman