Model calculations to determine the influence of air flow on aspiration coefficients of dust particles for two different sampling heads

Simplified flow models have been developed for vertical and horizontal elutriators in an air stream. By means of these it has been possible to calculate the particle paths in order to determine the aspiration characteristics. The model for the vertical elutriator gives aspiration coefficients A which are partly in agreement with the most recent theoretical results obtained by Davies and Subari; the experiments carried out by these authors yielded lower values for A. In the case of the horizontal elutriator the validity range of the flow model is only limited. The experiments show a higher decrease of the separation coefficient with increasing air flow rate than in theory. The possible causes are discussed.