An experimental study of the gravity flow of sorghum

Experiments have been carried out in order to identify some features of the flow of sorghum through an inclined channel. A channel was constructed usi ng acrylic plates so that the flow could be recorded. Two conditions of the sliding surface of the channel were simulated: a smooth surface (an acryli c plate) and a rough surface (a rubber sheet attached to the base of the ch annel). Some of the grains were painted white so that they could be tracked during the video recording. Thus, the velocity at the different elevations were measured and velocity profiles obtained for different slopes of the c hannel. The results show that the conditions of the sliding surface of the channel(rough or smooth) is a main factor to affect the flow. For a rough s urface and small angles, the results show an S-shaped curve of velocity pro file, with a small layer at the bottom which does not flow. As the slope of the channel increases, the depth of the section during steady-state flow d ecreases and the mean velocity increases. The flow discharge reaches a maxi mum at a slope larger than the angle of friction of sorghum. (C) 2001 Silso e Research Institute.