1964 年 33 巻 12 号 p. 887-894
A study on the flow of powder is made with a double cylinder type viscometer. By rotating the outer cylinder, both the torque exerted on the inner cylinder and the amplitude of torque fluctuation are measured. Experiment is made with a mixture of talcum powder and glass granules and with fatty acid smeared glass granules. By representing the torque in the early stage of rotation by To, that in the ultimate settled stage by T∞ and that at the N th rotation by Tn, the relation
is found to hold. The constant K represents the fluidity of powdered mass and is independent of the speed of rotation in most cases. With fatty acid smeared glass granules, it decreases with the increase of speed of rotation due to clotting of particles by cohesion. The internal friction coeffi-cient of powdered mass calculated from T∞ of the above equation is in good agreement with the result obtained by shearing box method. With powder mixtures, the torque fluctuation is of a complicated pattern because of separation of components while rotated. With fatty acid smeared glass granules, the amplitude of torque fluctuation decreases with the increase of amount of fatty .acid on granules.