Tyre/road noise mainly consists of two parts, air-pumping noise and noise created by vibrations of the tyre surface. Air-pumping is a collective concept for noise created directly in the contact between tyre and road. There are a number of suggested generation mechanisms for air-pumping noise but no general theory that can explain and predict the phenomena for all combinations of tyre, road and vehicle speed. This project attacs air-pumping from a different angle - the vehicle speed dependency of different types of noise sources. We assume that air-pumping noise is generated by monopole type of sources (similar to small, pulsating spheres). Then the sound pressure level caused by air-pumping must have a vehicle speed exponent around 4. In other words, the sound pressure level will be proportional to U4, where U is the vehicle speed. The, so far, better understood generation mechanism, tyre vibrations, have a U2 dependency. By analysing the speed exponent of tyre/road noise, the proportion of the two different components can be identified. This powerful tool allows for advanced investigations of the air-pumping phenomenon with the goal to understand how it can be predicted.
Influence of air-flow related sources to the total tyre/road
noise for a slick tyre rolling on a rough road surface.
The project is carried out at the Division of Applied Acoustics in the research group Vibroacoustics.
More information can be found at Leisstras homepage.
Keywords: tyre/road noise, air-pumping
Thomas Beckenbauer (Müller BBM GmbH)
Müller BBM GmbH (Projektleitung)
Chalmers University of Technology
Continental Reifen Deutschland GmbH
Karlsruher Institut für Technologie