Comparing Aerodynamic Terminal Velocity of Open and Closed Mouth Pistachio Nuts Using Wind Column

Abstract

Determining the terminal velocity as one of the important aerodynamic properties of particles and grains is essential for pneumatic separation, grading, and handling. A wind tunnel system was used in the present research to measure the aerodynamic terminal velocity of pistachio nuts. Some physical properties were measured and calculated. The effects of pistachio mouth status at four levels (closed, open, and semi-open mouth, and shell) were investigated on its terminal velocity. The volume, mass and density of that were 1.33±0.37 cm3, 0.97±0.31 g and 0.72±0.18 g cm3-1, respectively. The average aerodynamic terminal velocity of pistachio was 9.43±1.38 m s-1. The aerodynamic terminal velocity of the pistachio had a direct relationship with the studied physical characteristics, except for density. The terminal velocity of open-mouth pistachio nuts (9.50±0.61 m s-1) was significantly lower than that of closed (10.12±0.51 m s-1) and semi-open mouth (10.16±0.62 m s-1) nuts, with the terminal velocity of the shells (6.51±0.65 m s-1) showing the lowest values. The results revealed that terminal velocity can be considered for pneumatic separation of shells from pistachio nuts as well as the separation of open-mouth nuts from closed-mouth ones.

Keywords

• pistachio
• aerodynamic properties
• pneumatic separation
• terminal velocity