Aerodynamic Properties of Seeds

peculiarities of the behavior of seeds in an air current. The aerodynamic properties of seeds depend upon such factors as the dimensions, form, weight, and surface texture of the seeds. These properties are taken into consideration in constructing machines for cleaning and sorting seeds. Special devices are used for studying the aerodynamic properties of seeds, including pneumatic classifiers, in which an air current is passed up a vertical tube onto a rack of seeds. The velocity of the air current necessary to suspend the seeds is called the critical velocity. For example, the critical velocity for wheat grains equals 8 to 11 m/sec; for corn, it is 10 to 17 m/sec. The resistance of the seeds to the air current depends upon their sail quality (parusnost’)—that is, the cross-sectional area perpendicular to the current. The behavior of seeds in a current depends upon their specific sail quality, or the ratio of the seeds’ average cross-sectional area (in sq cm) to their mass (in g). The specific sail quality is characterized by the velocity pressure of the current which puts the seed in suspension. This pressure is measured by a micromanometer.