Aerodynamic Properties of Wheat Kernel and Straw Materials

Abstract

Terminal velocity and drag coefficient of wheat kernel and straw materials (Canadian variety) have been experimentally measured by suspending the particles in an air stream. The effects of mass and moisture content of wheat kernel, node position and length of straw on terminal velocity were studied. The results showed that mass and moisture content have significant effects (p<0.01) on terminal velocity. By increasing mass of the kernel from 0.02 to 0.05 g and moisture content from 7 to 20 %(w.b.), its terminal velocity increased linearly from 7.04 to 7.74 m/s and 6.81 to 8.63 m/s, respectively. Drag coefficient of the wheat sample (0,96) showed this kernel was similar to a cylinder in an air stream. The terminal velocity of the straws with different node positions (node free, end node, and central node) and lengths (1 to 10 cm) were measured from 2.53 to 4.85 m/s. Terminal velocity increased by increasing length from 1 to 2 cm and decreased by increasing length from 2 to 10 cm. The results showed that terminal velocity and drag coefficient of wheat straw depended on node position and the end node position had the highest terminal velocity and the lowest resistant coefficient. For air separation of Canadian wheat and straw, the air flow should be less than 7.04 m/s and more than 4.85 m/s. Keywords: