| Abstract [eng] |
The main purpose of this work is to experimentally investigate noise emitted by different silencers of different constructions. In order to experimentally investigate the sound pressure of the exhaust system, the theory of the method of conducting such experiments was analyzed. The first and second parts of the work presents theoretical material about the types of exhaust system, legal regulation of car noise. The stated standards describe the amount of permitted exhaust emissions in the exhaust system and the limit values for vehicle noise. In the third part of the paper, literature analysis was performed in which the modeling of fluid dynamics by numerical method was analyzed. Sound wave analysis, their origin and influence of sound pressure on the human body were performed. Discharge control of the exhaust system and sound tones were discussed. Analyzes of silencer geometry improvement and modeling using analytical calculations were performed. The fourth part presents a numerical analysis of silencers during the bachelor's work, which is necessary for comparing experimental and analytical results. The sound pressure of three exhaust systems with different silencers was experimentally determined. Analytically calculated muffler transmission losses. Correlation between backpressure, exhaust gas velocity and acoustic resistance when changing the geometry of the muffler model was investigated. In the experimental study, the maximum sound pressure was obtained in the third silencer, which has a higher throughput and reaches 101.83 dB. The lowest sound pressure is obtained in the diesel combustion engine exhaust system - 82.86 dB. Gasoline internal combustion engine exhaust system - 91.8 dB. . |
