Derivation of dimensionless relationships for the agitation of powders of different flow behaviours in a planetary mixer

C. Andre , Jean-François Demeyre (1) , Cendrine Gatumel (1) , Henri Berthiaux (1) , Guillaume Delaplace

1 RAPSODEE - Centre de recherche d'Albi en génie des procédés des solides divisés, de l'énergie et de l'environnement

This study investigates the bulk agitation of free flowing or nearly cohesive granular materials in a pilot-scale planetary mixer equipped with a torque measurement system. Our major aim is to investigate the effect of the flow properties of several powders, as well as that of the set of experimental conditions (engine speeds N-R and N-G), on the power consumption of such a mixer. Thanks to a previous dimensional analysis of the system, this influence is studied through the variations of the power P with a characteristic speed rich, defined from engine speeds and geometrical considerations. Two relationships involving dimensionless numbers are derived to describe the agitation process: N-pG = f (F-rG, Nu(R)/Nu(G) )and N-pM = f(Fr-M). For free flowing powders, a linear relationship is observed when plotting P against u(ch), and he resulting process relationship linking dimensionless numbers is Np-M = 15Fr(M)(-1). In the more cohesive case, power values vary around an average value (P = 54W) and the resulting process relationship is Np-M = 1.8072Fr(M)(-1.467). It is argued that the exponent in the representation of N-pM against Fr-M may be a useful parameter for powder classification, and should be linked to powder rheometrical considerations.

Mots clés: Dimensional analysis; Power consumption; Planetary mixer; Free flowing powder; Cohesive powder

Domaines: Sciences de l'ingénieur [physics]

C. Andre, Jean-François Demeyre, Cendrine Gatumel, Henri Berthiaux, Guillaume Delaplace. Derivation of dimensionless relationships for the agitation of powders of different flow behaviours in a planetary mixer. Powder Technology, 2014, 256, p.33-38. ⟨10.1016/j.powtec2014.02.002⟩. ⟨hal-01625038⟩