Perforation and muffler noise reduction system for a small petrol generator

University of Johannesburg, Department of Mechanical Engineering Science, Cnr University Road and Kingsway, South Africa

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Published online: 14 January 2026

Abstract

South Africa’s electrical infrastructure deficit and poor maintenance plans have resulted in frequently occurring power outages, which has caused a decline in productivity, alongside an increase in vandalism. As a result, many households and businesses have resorted to alternative energy sources, such as petrol generators. However, petrol generators are loud, reaching acoustic levels of roughly 90 dB, and have proven negative impacts on society and the environment. To reduce the noise intensity produced by small petrol generators, a noise reduction mechanism has been designed. The mechanism incorporates several noise attenuation materials such as porous absorbers and perforated panels. The design also features both passive and active ventilation features for optimal cooling of the generator during use. With flow simulating software embedded in SolidWorks, the temperature, pressure and acoustic power level within the noise reduction mechanism was investigated. The sound box is shown to reduce the noise of the generator to approximately 10 dB, whereas the muffler, can reduce the noise intensity to 37 dB. The overall temperature within the sound box is roughly 75 ˚C, and the maximum pressure was determined to be 103 kPa, which is sufficient for operation of the generator, without compromising its performance and functionality. A modified experimental model was built to validate the numerical results. The results from the experiment produced similar results in terms of decrease in sound when the insulator is added.