The Coanda effect in gas-dynamic noise control

The principle types of silencers are discussed for gas dynamic noise of free steam and gas expansions, as well as the results of research in gas dynamics of jets and applied acoustics. Gas dynamic noise attenuation by means of the Coanda effect is due to fluid decompression in a Coanda ejector of the external type, where a structural change takes place in the acoustic frequency spectrum and in its direction, as well as a substantial decrease in the fluid's velocity, temperature and concentration. This process is continued in the second phase with absorption of the acoustic waves by means of an active structure.