Riassunto analitico
Noise regulations for motorcycle have become more and more stringent over the years and are in contrast with the performance of a motorcycle with a sporty soul. One of the main sources of noise, in this type of vehicle, is the exhaust: this part in the same time must expel combustion gases from the cylinders with the least pressure losses in order not to aect the performance of the engine and, in its path, it has to reduce the level of sound pressure at the exhaust in order to stay within noise regulations. This thesis activity aims to measure and analyze the sound level of a motorcycle that performs the maneuvers required by the UNECE R41; these manuvers are called WOT, acronym of Wide Open Throttle, in which driver enters proving ground and accelerate opening throttle completely and CRS in which driver ride at constant speed. These two type of manuvers will be performed by changing the diameter and length of the tailpipe. In addition to the sound level measurements, static pressure measurements will be carried out in the exhaust manifolds and at the exit of the pre-muer in order to correlate the back-pressure at the exhaust with the sound level measured from the outside. On the same vehicle, temperature measurements will be taken with the aid of K-type thermocouples; these will be employed, in conjunction with pressure measurements, to improve the 1D fluid dynamics model already in use for the development of exhaust systems
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Abstract
Noise regulations for motorcycle have become more and more stringent over the years and
are in contrast with the performance of a motorcycle with a sporty soul. One of the main
sources of noise, in this type of vehicle, is the exhaust: this part in the same time must
expel combustion gases from the cylinders with the least pressure losses in order not to
aect the performance of the engine and, in its path, it has to reduce the level of sound
pressure at the exhaust in order to stay within noise regulations.
This thesis activity aims to measure and analyze the sound level of a motorcycle that
performs the maneuvers required by the UNECE R41; these manuvers are called WOT,
acronym of Wide Open Throttle, in which driver enters proving ground and accelerate
opening throttle completely and CRS in which driver ride at constant speed. These two
type of manuvers will be performed by changing the diameter and length of the tailpipe.
In addition to the sound level measurements, static pressure measurements will be carried
out in the exhaust manifolds and at the exit of the pre-muer in order to correlate the
back-pressure at the exhaust with the sound level measured from the outside.
On the same vehicle, temperature measurements will be taken with the aid of K-type
thermocouples; these will be employed, in conjunction with pressure measurements, to
improve the 1D fluid dynamics model already in use for the development of exhaust
systems
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