Sound power measurements on heavy vehicles to study propulsion noise in the EU-project IMAGINE
Typ
Examensarbete för masterexamen
Master Thesis
Master Thesis
Program
Publicerad
2005
Författare
Keulemans, Christina
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The aim of this project has been to measure the sound power level of the propulsion noise from a heavy vehicle at constant speed. The measurement results have been compared with the Harmonoise/Imagine source model for heavy vehicles. The model will be used for noise mapping purposes. The influence of driving style, vehicle load and road gradient was also studied. Finally a city cycle test, including different driving modes; acceleration, constant speed, engine braking and low idle, was performed. The work has been performed indoors at the Noise and Vibration Laboratory at Volvo Trucks, Göteborg. Partly in the powertrain rig where the truck cab, with standard noise muffler and noise shields, was built up around the driveline, and partly in the truck noise chamber where the rear tires where encapsulated. The sound power level in third octave bands was measured according to ISO 3744 using a parallelepiped measurement surface. The tested vehicle is a typical long distance truck with a 480 hp engine. The simulated load was 30 tonnes and 18 tonnes for the powertrain rig and the truck noise chamber respectively. The results indicate that the vehicle speed dependent source model shows too high values at higher speeds. The measurements show also that the propulsion noise at constant speed can be modelled as constant below 50 km/h. The sound level increases above 50-55 km/h with the increased engine speed. A rougher driving style defined as driving with one gear lower than most suitable gear, leads to an averaged noise increase of 2,3 dBA in the powertrain rig and 1,4 dBA in the truck chamber. Simulating different vehicle load at horizontal road and with constant speed showed no influence on the emitted noise. Driving on positive and negative road grades in these measurements showed approximately the same noise increase in both up- and downhills due to increased engine load. The city cycle test showed that the difference between the maximum and minimum sound power level is 14 dB with the simulated truck.
Beskrivning
Ämne/nyckelord
Samhällsbyggnadsteknik , Civil Engineering