1-D acoustical analysis of axial-inlet, transverse-outlet air cleaners of rectangular and circular cross-section

This paper deals with the prediction of the acoustical performance of two basic types of air cleaners: 1 ) rectangular axial-inlet transverse-outlet (RAITO) and 2) circular axial-inlet transverse-outlet (CAITO), through 1-D acoustical analysis. Predictions of the acoustical performance of the air cleaners have been validated with 3-D FEM results. The acoustical performance of the cleaner box has been compared with the bare plenum performance (without any filter element) in order to estimate the acoustical performance of the filter element. It has been shown that even if inlet and outlet pipes do not lie exactly on the centre of the corresponding cross section, the 1-D formulation still can predict the transmission loos (TL) with reasonable accuracy in the low- and mid-frequency zones. The 1-D model presented here is not only more convenient and much faster than the 3-D model, and it has the additional advantage of being able to incorporate the effect of mean flow, particularly the dissipative effect of mean flow at the inlet/outlet of the air cleaner. This 1-D model would facilitate a rational design of an air cleaner for control of the intake noise of internal-combustion engines.