Test Bench for the Acoustic Behaviour of Air-Boxes for Motorcycles 2002-32-1812

Air-boxes as a part of the intake system of small engines especially for motorcycles create a specific noise radiation. Simulation methods and experimental investigations to analyse and predict the acoustical behaviour of air-boxes for motorcycles are required in order to pass current noise control legislation and to achieve a pleasant sound.

This paper presents the design of a test bench for the investigation of air-boxes for motorcycles. The test bench is equipped with measurement systems for monitoring and recording volumetric flow, speed, pressure data and sound data.

The sound radiated from the air-box is produced by the pulse flow in the engine induction system. The investigation of the air-box sound at real engine operation is impossible because of the noise produced by the engine. The created gas exchange system is distinguished by a rotating disc with a cut-out section, which opens and closes a pipe instead of the valves in the real engine.

The proof of the function was carried out by comparing of the pressure data received at an engine test rig with the data obtained from the gas exchange system.

Finally, the paper presents acoustical investigation of air-boxes. Different configurations of the air-box were defined to evaluate the acoustical properties.