Investigating the Effect of Acoustic Performance on Vibration Signatures for Optimized Hybrid Muffler

Noise is an unwanted that has a significant impact on people’s health over time. One such unwanted noise is produced by high-pressure gases that emerge from an automobile’s exhaust system.

This exhaust noise is hampering human health, causing a rise in different health problems. The mitigation of such noise is necessary and can be lessened by the muffler. A hybrid muffler is one such muffler that dissipates high-pressure gases and is made up of baffles, tubes and sound-absorbing materials.

In this study, a hybrid muffler is considered for study. The acoustic analysis of the muffler is carried out using pressure acoustic frequency domain analysis in COMSOL and experimentation is performed in an impedance tube set-up. During the experimentation, vibration signals are also acquired with the help of an accelerometer, by placing it at three positions namely the inlet tube, centre and outlet tube of the muffler. The Fast Fourier transform (FFT) analysis is performed for the acquired signals which is followed by wavelet analysis.

From this analysis, the Fejer-Korovkin wavelet having a vanishing moment (N) of 12 is selected as the most suitable wavelet for analysis of vibration signal. Statistical analysis is then performed using this wavelet and Shannon entropy to know the effect of vibration on the muffler. The sensitivity analysis for the Shannon entropy showed a percentage variation of 58.69%, 52.08% and 47.74% from the inlet section to the outlet section of the muffler as compared to 68.47%, 65.29% and 62.15% for the SPL. Thus, the Shannon entropy and sound pressure levels (SPL) obtained from vibration analysis and acoustic analysis respectively correlate with each other. Thus vibration analysis could be taken as an effective method for knowing SPL throughout the muffler.