Study of Active Muffler for Engine Exhaust Systems

• Main Authors: Chien-Hung Shen, 沈建宏
• Other Authors: Jin-Siang Show
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/82953534938985909797

碩士 === 華梵大學 === 機電工程研究所 === 90 === This thesis presents design and control of active mufflers used in engine exhaust systems. Boundary element method in SYSNOISE is employed to investigate noise attenuation performances of various active muffler structures. Based on these performance evaluations, an active muffler having only one loudspeaker inclined at 45 degree with the muffler centerline is constructed and tested for active noise control (ANC). The feedback ANC with two controller tuning algorithms, the filtered-x least mean square (FXLMS) algorithm and Godard modified algorithm is applied independently for engine exhaust noise attenuation. Experimental investigation reveals that feedback ANC with FXLMS algorithm can attain an averaged 23.6 dB noise attenuation for pure tone excitation and over 6 dB noise reduction for motorcycle and automobile exhaust noises. It is also shown that feedback ANC with Godard modified algorithm has faster transient response compared to FXLMS algorithm for a pure tone noise, but has inferior noise attenuation capability than the FXLMS algorithm for the engine exhaust noise at fixed speeds (about 5 dB noise reduction) as well as during run-up tests.