# Design and Testing of a Gasoline Engine Muffler Based on the Principle of Split-Stream Rushing
## 4 Discussion  
Orthogonal tests were implemented to ascertain the optimal combination of structural parameters for the split-stream rushing muffler. LMS. Virtual. Lab and Fluent were utilized to simulate the Transmission Loss and fluid dynamics of the muffler. Through modifying the structural parameters, namely the perforation aperture of the perforated pipe, the perforation rate of the perforated pipe, and the perforation rate of the perforated plate, the acoustic and aerodynamic performances of the muffler exhibited varying degrees of alterations. Orthogonal tests were deployed to identify the main factors influencing the sequence, with the perforation rate of the perforated plate being the most significant, followed by the perforation aperture of the perforated pipe, and then the perforation rate of the perforated pipe. Upon analyzing the outcomes of the orthogonal test, the optimal combination of the structural parameters was established as a perforation aperture of 8 mm for the perforated pipe, a perforation rate of 10% for the perforated pipe, and a perforation rate of 15% for the perforated plate. By comparing the simulation results of the Transmission Loss of the split-stream rushing muffler and the original muffler, it was found that in the main muffling frequency band from 300 Hz to 1000 Hz, the average Transmission Loss of the split-stream rushing muffler was 41.91 dB, and the average Transmission Loss of the original muffler was 34.13 dB, whereas the average Transmission Loss of the split-stream rushing muffler was 7.78 dB higher than the average Transmission Loss of the original muffler. At the same time, the transfer loss in the main muffling frequency band was summed and calculated, and it was found that the transfer loss of the split-stream rushing muffler was 22.91% higher than that of the original muffler. Secondly, in the high-frequency region after 1000 Hz, the Transmission Loss of the split-stream rushing muffler was higher than that of the original muffler. In terms of aerodynamic performance, the Pressure Loss of the split-stream rushing muffler was smaller than that of the original muffler. Through the insertion loss test and test bench Pressure Loss test of split-stream rushing muffler, it could be seen that the muffling performance of split-stream rushing muffler was better, and the suppression effect was obvious for the main muffling frequency band and high-frequency noise. These results provide valuable references for the performance optimization of mufflers. However, it should be noted that these conclusions are obtained through simulation software under ideal conditions. The software was unable to simulate real-world scenarios, and its effectiveness in practical applications might have been somewhat limited. It is necessary to consider numerous complex factors present in the real world, such as ambient temperature, humidity, wind speed, and geographical location. Future research could further enhance the evaluation and optimization of muffler performance by improving field test conditions and other methods, thereby providing more accurate and reliable data support for practical applications. The acoustic performance of mufflers improved as the temperature rose, and gasoline engines typically had relatively high exhaust temperatures. Due to technological limitations, this paper did not consider the influence of temperature on muffler performance, which could be taken into account in subsequent research. Conceptualization, S.A. and H.Y. ; methodology, Y.L. ; software, M.J.; validation, Y.M., H.S. and J.X. ; formal analysis, Y.L. ; investigation, H.Y. ; resources, M.J.; data curation, S.A.; writing--original draft preparation, S.A.; writing--review and editing, H.Y. ; visualization, J.X. ; supervision, H.S. and W.J. ; project administration, Y.M. ; funding acquisition, J.X. and W.J. All authors have read and agreed to the published version of the manuscript.