Viscosity measuring technique for gas-solid suspensions

It is important that we clarify the interaction between particles in particle processing. The interaction between particles under shear flow is considered to be evaluated by energy dissipation, i.e. viscosity, in a powder layer. By measuring the torque exerted on the mixing blade of a powder rheometer, the viscosity of the powder layer could be calculated. The viscosity decreased with the blade velocity and such a shear thinning rheological property is similar to that observed for solid-liquid suspensions. By applying the suspension rheology model, which was developed for the evaluation of the agglomeration state of solid-liquid mixtures under shear flow, particle agglomeration around the blade under dry powder flow conditions was evaluated. As the shear rate increases, the size of agglomerated particle clusters is proved to decrease. At high shear rate or low solid volume fraction, the inter-particle bonding energy is revealed to be constant independent of the shear rate and solid volume fraction.