Particulate matter emissions represent a significant health risk for humans. The so-called exhaust emissions of vehicles have been regulated for many years, whereas emissions such as brake dust and tire abrasion (so-called non-exhaust emissions), which have a high proportion of total particulate emissions of road transport, will only be regulated in EU7 for the first time. The friction process between brake pad and brake disc produces fine dust particles, of which a large part is emitted into air. This flow behavior of brake fine dust particles into the wheel has not been investigated under realistic conditions so far. In this work, a test setup was developed allowing to analyze the flow of the brake dust particles of a disc brake under (almost) real driving conditions with contactless optical flow measurement technology (3C Stereo Particle Image Velocimetry) into a rotating wheel of a vehicle into a wind tunnel. The experimental is a good starting point to enlarge the system with a brake dust particle filter to evaluate local flow effects. The study shows how flow conditions are affected by real flow around the wheel. The flow into the car rim is significantly changing with and without external flow. In addition, there is a dependence of fine dust particle flow on vehicle velocity and the associated inflow. The laminar-turbulent transition of brake disc boundary layer is decisive for the emission of the particles and changes at increasing speed. Additionally first investigation with a mounted brake dust particle filter were done and the influence on the flow behavior will be discussed in the area around the brake system within the environment of a rotating wheel.
Ing. Kai Götz, Test Engineer, Volkswagen AG; Ing. Calvin Zmuda Trzebiatowski, Mechanical engineer, Ostfalia Hochschule für angewandte Wissenschaften; Prof. Dr.-Ing. Falk Klinge, Professor for applied fluid mechanics, Ostfalia Hochschule für angewandte Wissenschaften; Dipl.-Ing. Frank Stebner, Test engineer, Volkswagen AG; Dipl.-Ing. Tobias Wörz, Lead Product Engineer, MANN+HUMMEL GmbH; Ing. Benedikt Weller, Lead Product Engineer, MANN+HUMMEL GmbH