Airflow through crushed-rock layers

Pressure drops through packed concrete spheres and crushed rocks were investigated by wind tunnel experiments. The diameters of concrete spheres were 0.041 m and 0.052 m, respectively. The mean particle size of the crushed rocks was 0.096 m. The experimental results show that the Ergun equation with revised coefficient values can be used to predict pressure drops through the coarse spherical particle beds. A practical Ergun-type equation for arbitrary shape particles has been developed based on Krumbein sphericity. The coefficient values of the practical Ergun-type equation for crushed-rock layers were measured.