Studies on the Terminal Velocity of Grains (II)

In Case of Grain Group

Abstract

To obtain the mean actual terminal velocity of grain group, the mean rising velocity of the rough rice group in the vertical pipe were measured. The results obtained were as follows.
1. The mean rising velocity of the rough rice group increased as the air velocity and the weight ratio of the rough rice to air in flow increased (Fig. 2).
2. The mean actual terminal velocity of rough rice group increased as the air velocity increased and it decreased as the weight ratio of the rough rice to air in flow increased (Fig. 3).
3. In the range of the air velocity from 9.2 to 13.5m/s and the weight ratio of the rough rice to air in flow from 0.7 to 2.8, the mean actual terminal velocity Vtg could be expressed as the empirical equation (5).
4. At the weight ratio of 1.0, it was considered that the rough rice rised to take with the posture as its intermediate direction between X and Z axes to be nearly parallel to the direction of air stream in the low air velocity about 9.0m/s and as its X axis to be parallel to the air stream in the high air velocity about 13.5m/s in the vertical pipe. At the weight ratio of 3.0, it was considered that the rough rice rised to take with the posture as its nearly intermediate direction between Z and Y axes to be parallel to the direction of the air stream in the low air velocity about 9.0m/s and as its intermediate direction between X and Y axes to be nearly parallel to the direction of the air stream in the high air velocity about 13.5m/s.
5. If the theoretical terminal velocities of grain on given three axes are determined, it becomes possible to estimate the mean actual terminal velocity and the mean rising velocity of grain group at the certain air velocity and weight ratio of the grain to air in flow in the vertical pipe, using the flying orientation coefficient n (described in the paper I) for the other grains which their shapes are similar to the rough rice.