Conference_programme: 19.1 - Duct Acoustics
Lecture: Design and testing of a muffler for agricultural tractors
Author(s): Piana Edoardo Alessio, Uberti Stefano, Copeta Alessandro, Carlsson Ulf Eric
Summary:
This work focuses on the design of a new muffler for SAME Deutz Series 6 agricultural tractor with the aim of containing the noise emissions within the limits given by the international standards. This vehicle is already produced by the company, it is equipped with a diesel engine able to deliver over 200 HP, and can be particularly noisy at low RPM. Typically, the noise emitted by agricultural tractors is due to the engine and the transmission since the maximum speed is limited to 60 km/h. The maximum sound pressure level allowed by the European Community during pass-by tests is 85 dB(A) at 7.5 m and the noise contribution due to the tire-ground contact is far below the contribution of the engine-transmission system. As concerns the noise emitted by the engine and the exhaust system in static conditions, the test procedure prescribes a sound pressure level measurement to be performed at 0.5 m from the outlet section, 45° angle from the exhaust axis. In this case the maximum permitted sound pressure level is 89 dB(A). The design constraints given by the tractor’s manufacturer are the maximum pressure drop in the muffler path and the available volumes to fit the system “under the bonnet”. Additional available pieces of information were the sound pressure level emitted by the engine without any exhaust system and the drawings of a muffler used in a previous version of the vehicle. The design has been made by using SIDLAB, a lumped parameters simulation software based on an electro-acoustic analogy. After the design stage a prototype has been manufactured and tested at the MWL/KTH laboratory. The agreement between the predictions and the measurements is discussed.
Corresponding author
Name: Dr Edoardo Alessio Piana
e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Country: Italy
