AN EXPERIMENTAL STUDY ON EFFECTS OF GLASS-WOOL ON TRAVELLING WAVES IN A DOUBLE-CAVITY MUFFLER

Document Type : Original Article

Author

Mechanical Power Engineering Department, Faculty of Engineering, Shebin El-Kom, Minoufiya University, Egypt

Abstract

A muffler is a device designed to reduce the emission of the noise produced from cars engines. Reactive muffler of coupled tubes with or without absorbing materials is experimentally studied in the present paper. Finite amplitude oscillations superimposed on cold gas flow is created by a reciprocating engine of a compressor. For coupled tubes, the experimental results had been taken at different speed (different initial frequencies). Capacitive pressure transducers are used to record pressure history variations. These transducers were connected directly to computer through a Lab View soft ware. Also the power spectrum is calculated from experimental data.
In the case of pipe system arrangement consists of large cavity followed by small one without absorbing materials, it is found that there are no big change in the recorded pressure traces before and after the big cavity. In contrast, in case of existence absorbing materials embedded along the big cavity, smooth pressure waves are noticed at the exit of the large cavity. Moreover, adding glass-wool in the adopted double cavity muffler reduces the outlet noise at the muffler exit and increase in pressure downstream of the large cavity based on the generated complex pattern in the system. Results of this investigation are useful for the muffler designers in order to reduce the output noise levels.

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