PREDICTION OF THE CONCENTRATION OF AIRBOR NE DUST IN THE WOODWORKING CHAMBER .1. TIME CHANGES OF THE CONCENTRATION AND DISTRIBUTION OF PARTICLES IN FREE FALLING

The concentration of fine airborne:dust generated in the process wood grinding in a woodworking chamber was measured, and the shapes of the dust particles fallen on a glass plate were analyzed by an image analy zer. The time changes of the dust concentrations as well as of the dis tributions of the particle sizes were predicted by computer simulation s, when the drag-force, due to the friction between the particles and air, is generated on the particles in free falling; The predicted conc entration favorably corresponded to the measured concentration. Howeve r, it revealed the influence of shapes of the fine particles on the fa lling speed, which were observed in an image analysis and of the irreg ular shapes, should be taken into consideration for more correct simul ations.