Growth of Exhaust Pulsation Resonance during Rapid Engine Acceleration

The purpose of the present study is to improve the on-street exhaust noise measurement technique for regulating vehicles emitting unacceptably large exhaust noise. The method under development uses racing operation of engines with a wide-open throttle. Due to the high engine acceleration in this operation, exhaust pulsation amplitudes at resonant speeds may not increase sufficiently to represent the amplitudes under full-load acceleration conditions. To investigate the seriousness of this problem, experiments and numerical simulations were conducted. As a result, the sound level measurement error caused by the insufficient resonance growth was found to be sufficiently small for on-street tests.