Effect of ventilation design on removal of particles in woodturning workstations

Wood processing tasks such as circular sawing and turning that is associated with woodturning operators produce particularly high exposure levels. A computational model including a humanoid and lathe within a test chamber was simulated with monodisperse particles under five different ventilation designs with the aim of reducing the particle suspension within the breathing zone. A commercial CFD code was used to solve the governing equations of motion with a k-(epsilon) RNG turbulence model. A discrete Lagrangian model was used to track the particles individually. Measurements to evaluate the efficiency of each ventilation design included total particle clearance and the percentage of particles crossing through the breathing plane. It was concluded that the percentage of particles that cross the breathing plane is of greater significance than the other measurements as it provides a better determination of exposure levels. Ventilation that emanated from the roof and had an angled outlet provided greatest total particle clearance and a low number of particles in the breathing plane. It was also found that the obstruction from the local roof ventilations caused separation of the air that flowed along the ceiling to produce a complex flow region. This study provides a basis for further investigation into the effects of particle size and density on the particle flow patterns and potential inhalation conditions for a given ventilation design.