Investigation of particle detachment from the rotating wheel in indoor environment

Abstract

There are various wheels are required for indoor activities, such as spinning bike wheels in the gym, various mechanical equipment wheels in the factory. Obviously, these rotational movements of wheels will cause the detachment of particles adhering to the wheel. This common phenomenon is regarded as an important contributor to particulate matter concentrations in indoor environment. The work performed in this study mainly focused on the description and understanding of the process of particles detachment from the rotating wheel into the air. A set of theoretical models were proposed to clarify particle detachment mechanisms. Since the detachment occurs when the sum of external force moments exceed the maximum adhesion resistance moment, different forces acting on the particles should be considered before the particles detached. There are adhesion forces between the particles and the wheel surface, hydrodynamic forces acting on the particles and centrifugal forces due to the rotating wheel. In order to verify models, the corresponding experiments were carried out and the experimental results were quite consistent with the calculation results of models. Results showed that adhesion force, hydrodynamic drag force and centrifugal force were important and critical detachment diameters of particles adhering to the wheel can be influenced by these forces. Effects of different relevant parameters on these forces, including surface roughness, wheel speed, particle size were analysed. Higher roughness, larger particle and faster wheel speed are more conducive to the detachment of particles.