Attract Pressure Tanker Noise Study

In this dissertation,research has been done on lowering noise of the suction-pressurization tank car, which is used in smelting plants and makes serious noise pollution. The Roots vacuum pump,which is the main working parts of the tank car,brings high noise because of the countercurrent used for cooling. To solve this actual engineeringproblem,the technology way is,noise sources identification------lowering noise------effectevaluation.At first,the mechanism of the tank car and the Roots vacuum pump was studied in order to get a general understanding of the main noise sources.The cooling process of the pump was elaborated on emphases and it turned out that intense jet noise would happen.Sound intensity that measured around the tank car indicated that the noise from Roots vacuum pump was the main noise source. Frequency analysis showed that the noise was consist of aero noise at the medium and low frequency,with 80Hz,120Hz and 200Hz as its main frequency.A resistance muffler was designed in order to lowering the main noise that has been identified before. To predict the acoustics performance of the muffler,numerical simulation was taken by acoustic software SYSNOISE,in which the interior sound field of the muffler was simulated by finite element method and the transmission loss was calculated.Effect evaluation was done by contrast between the noise data that tested with three different mufflers(which were, the original muffler, the muffler without reducing vibration,the vibration reduced muffler)assembled on the tank car.The result turned out that the solutions were very effective.It also indicated that reducing vibration of the muffler is very important when lowering noise.