Effect of awn on aerodynamic properties of paddy grains (Oryza Sativa L.(

Abstract

Paddy grains (rough rice) are categorized into two groups, awned and awnless paddies.The awn is a needle-like appendage that extends from the lemmas of the florets and is important domestication and agronomic traits in paddy. The aerodynamic properties of paddy grains and understanding the effect of awn on the aerodynamic properties of paddy are important information for grain harvest and postharvest process like cleaning, handling and for designing related systems. So in this research, aerodynamic properties of two local varieties of paddy (Hashemi and Gilaneh) and effect of awn as specific traits on aerodynamic properties were investigated in different moisture content. Terminal velocities were measured for awned and de-awned paddy grains using the suspension velocity method. Also the drag coefficient for de-awned paddy and resistance coefficient for awned paddy were calculated from the experimentally obtained terminal velocities. Mean value for terminal velocity of the awned and de-awned paddy was obtained 5.88 and 5.73 m/s respectively, that shows de-awning of paddy decreases the terminal velocity of paddy 2.55 %. Drag coefficient of de-awned grains decreased with increase in moisture content, whereas resistance coefficient of awnd grains increased. Obtained aerodynamic properties values provided baseline data which are useful in the design of pneumatic conveying devices.