Noise emission and noise sources of a hybrid bus
PALLAS ; CHATAGNON ; LELONG
Type de document
CONFERENCE INVITEE (INV)
Langue
anglais
Auteur
PALLAS ; CHATAGNON ; LELONG
Résumé / Abstract
Awkward environmental conditions induced by dense traffic in urban areas lead many cities to expand sustainable public transportation services. In addition to contributing to the reduction of air pollution and energy consumption, the selection of hybrid buses against conventional buses may also impact on noise emission. The French research project ElLiSup has been developing a plug-in series hybrid bus, operating either in hybrid or electric mode. The noise emission of the vehicle has been assessed and compared with an equivalent Internal Combustion Engine (ICE) bus. Global and third-octave noise analysis has been performed, relying on the classical Controlled Pass-by (CPB) procedure, and on a microphone array beamforming technique for investigating the noise sources. Pass-bys at constant speed, with acceleration and braking have been considered. The hybrid bus provides significant noise reduction at constant low speed due to lower powertrain contribution, both in hybrid or electric mode. This advantage decreases with increasing speed, as rolling noise becomes prevailing. However, in some acceleration or even braking situations the increase of the motor’s contribution in frequency ranges of high human ear sensitivity may put the hybrid bus at a disadvantage, even in electric mode.
