A THEORETICAL PREDICTION OF THE DISCHARGE RATE FROM CONICAL HOPPERS IN BOTH THE MASS-FLOW AND CORE FLOW REGIMES

The Hour Glass Theory of Davidson and Nedderman was one of the first t heoretical predictions of the discharge rate from conical hoppers. Bec ause of the assumptions in the theory, it was applicable only to narro w-angled, smooth-walled hoppers and even here it over-predicted the ma ss flow rate. Subsequent workers have incorporated the effects of wall friction with minor improvements to the accuracy. In this paper allow ance is made of the non-uniform velocity distribution in the hopper. T his enables the theory to be extended to wider angles and into the cor e flow regime. The resulting predictions are in good agreement with es tablished correlations in the mass flow regime but there is less satis factory agreement in core flow.