Active noise control of exhaust noise from actual diesel engine using secondary identical sources

Abstract

Exhaust noise of diesel engines from a muffler is contributed from low frequency tonal components. The tonal component originates from the explosion process of the engine, and radiates as a monopole from the muffler outlet. Generally, passive muffling systems incorporating sound absorbing material are used for dissipating unwanted sound, but exhibited limited Performance for low frequency noise below 500Hz. In this study, active noise cancelation (ANC) using FxLMS algorithm after analyzing the characteristic of diesel engine noise such as the number of cylinders and the revolution of engine is proposed to reduce the exhaust noise. The low frequency tonal noise was reduced very effectively by Converting the sound radiation characteristics into dipole or quadrupole through the proposed ANC. The noise reduction was verified through experiments using scale model and the actual diesel engine ystem.