Noise Analysis Of Diesel Generator Set And Acoustic Simulation Of Exhaust Muffler

Currently, industrial noise pollution has become a growing concern. Diesel generator sets have been widely used as a backup power. Noises above100dB produced by diesel generator sets seriously endanger human body health. Therefore, reducing the noise of diesel generator sets has become an important task to the generator set manufacture. To reduce the noise level of diesel generator set, one diesel generator set,220kW, made by New-Line Machine&Electricity Equipment Co., Ltd was taken to test and analyze noise, and an engine exhaust muffler was designed based on acoustics FEM. The main contents and results are as follows:(1) To understand the noise of diesel generator set, noise testing for the diesel generator set was taken according to GB/T2820.10-2002"Reciprocating internal combustion engine driven alternating current generating sets-Part10:Measurement of airborne noise by the enveloping surface method". The method of average sound pressure level and average sound intensity was used for processing noise test data. Frequency domain analysis was taken for analyzing the processed noise data, draw a conclusion that exhaust noise and cooling fan noise are the one of main noise. It provides the reference for reducing the noise of diesel generator set.(2) To reduce exhaust noise, a muffler was chosen. The characteristics of basic muffler units have much impact to acoustic characteristics of mufflers. It was found that the transmission loss of muffler units with parameters changes in the law, by acoustic simulation analysis for muffler units. It provides the basis to exhaust muffler design.(3) According to the noise test results and based on the purpose of30dB reduction for exhaust noise, firstly, it was designed a muffler with three-chamber, straight-through pipe and internal perforated tube by using empirical formula. By acoustic simulation, it was found the frequency band which amount of noise reduction is zero. Then, the muffler was improved based on characteristics of muffler unit, inserted two small expansion chambers at the internal baffle plates of the muffler, and designed perforation at the insertion tube of each chambers. Finally, it was conducted acoustic simulation analysis for the muffler improved, and taking into account the maximum exhaust flow rate and the average temperature, good results of noise reduction is obtained in the region of less than3000Hz. The muffler designed meets the design requirements basically.The study results and conclusion of noise measurement and analysis for a diesel generator set, research findings for the characteristics of muffler unit’s transmission loss and the design of a muffler in this paper can provide reference for the noise reduction of diesel generator sets.