NOISE-CONTROL OF ENGINE DRIVEN PORTABLE GENERATOR SET

Major noise sources in a noisy portable I. C. engine driven generator set have been identified. The generator set engine is petrol start and kerosene run. The exhaust silencer of the engine was providing substa ntial insertion loss, The separation of engine combustion and mechanic al noise indicated that their contribution was almost equal. Since gen erally combustion noise is more than mechanical noise, the main noise sources were considered to be mechanical in nature. Sound intensity me asurements were performed to identify major noise sources in the gener ator set when the exhaust was ducted away. The results of these measur ements indicated that the main sources of noise in the generator set a re: cooling fan cover, silencer shell, silencer cover and the engine c rankcase. Noise control measures were applied to these parts. Sound pr essure and power levels were measured before and after the application of noise control measures. Constrained layer damping treatment and st iffening Of the cooling fan cover had a combined effect of reducing th e sound pressure level by about 3 dB(A). Rigid clamping of the silence r also reduced the noise level. A partial enclosure was designed for t he generator set. The partial enclosure reduced the sound pressure and power levels by about 4 and 3.7 dB(A), respectively. There was an inc rease in the engine cylinder head temperature due to the enclosure, bu t the increase in temperature was considered to be safe. An overall no ise reduction of 8.5 dB(A) was obtained on side 4 of the generator set as a result of the implementation of all the noise control measures. The noise reduction on the other sides of the generator set was also s ubstantial. (C) 1998 Elsevier Science Ltd. All rights reserved.