| Abstract [eng] |
Numerous literatures were studied to evaluate the significance of mufflers in the exhaust system. As mufflers are an integral part of the exhaust system, the design parameters must be carefully accessed to obtain the required outcome. Mufflers are often associated with the scope of sound attenuation property. In this research, a base muffler is chosen to evaluate and validate the analysis simulation parameters to establish the test conditions. The process of evaluation was carried out using Solidworks and Ansys software platforms to determine the analysis outcomes to later compare with existing data. A comparison of the experimental and theoretical values is obtained to validate the results. Further optimized design variants of mufflers were designed using the Solidworks platform to determine the effects of different obstructions introduced in the expansion chamber. Three different design variants of these designs were considered for data analysis purposes. The design variants further have design variations with the difference in the obstructions. The initial analysis was to determine the effect of baffle plates and then baffle plates with obstruction and finally baffle plates with perforated pipes. The combinations of these design variants were analyzed to test the effects of these different types of obstructions. These design variants were analyzed using Solidworks to determine the velocity and pressure trajectories. From the results, the surface velocity of the flow was gained which served as the input to determine the transmission loss on each design variant on Ansys. From the analysis, it is evident that the different obstruction design parameters placed in a different position provide different acoustic loss properties to the flow. The laminar flow at the entry is converted into a controlled laminar flow using the obstructions to attenuate acoustics. From the simulation results, a comparison study was created to understand the impact of the design obstructions inserted into the expansion chamber on transmission loss. This study represents that each obstruction creates a significant amount of acoustics loss. Design 1 yields the maximum transmission loss with the design 1.3 variant having 13.21 dB at 1380 Hz. Design 2 yields the maximum transmission loss with the design 2.3 variant having 99.56 dB at 680 Hz. Design 3 yields the maximum transmission loss with the design 3.1 variant having 116.13 dB at 1300 Hz. Irrespective of the shape of the expansion chamber the baffle plate and perforated pipes create an impact. But to conclude, the position, shape, and size of the obstructions and the design of the expansion chamber play a major role in impacting the transmission loss. Even though studies are stating the performance of reactive mufflers under low frequency, it can be seen that the design of the muffler and expansion chamber alters the transmission loss irrespective of the frequency range. Depending on the needs we can design the muffler and the expansion chamber to perform under a specific frequency range. . |
