Aerodynamic Characteristics of Jojoba Seeds and Like-Sized Stones

The aerodynamic behavior of jojoba seeds and like-sized stones was studied using both vacuum and positive pressure. The influence of air velocity at the head face, head height, and head angle on the distance at which seed motion was initiated were determined to establish an optimal set of conditions to facilitate seed and stone separation during harvesting. Trials indicated that a head face velocity of 10 m/s (32 ft/s) was required to blow jojoba seeds, and that a velocity of 30 m/s (100 ft/s) was required to vacuum them. Effective air distance increased as head face velocity increased, as head angle decreased when blowing, and as head height decreased while vacuuming. Blowing does not appear to be an effective technique for seed collection, however it may be useful for windrowing. For effective separation of seeds and stones vacuum heads should be mounted as high as possible without compromising retrieval of the seeds.