Modeling and optimization of aerodynamic properties of pigeon pea (Cajanus cajan (L.) Millsp.).

Mathematical modeling and optimization was carried out in other to create and provide data for designing harvesting, processing, handling and storage machines or equipment using air for cleaning, sorting or separating pigeon pea seeds. Two varieties (Flavus and Bicolor) of pigeon peas seeds were conditioned from their initial moisture to 8, 10, 12, and 14% d.b, for the determination of terminal velocity and drag coefficient. Seeds samples of weight 50,100 and 150g were poured into a constructed air aerodynamic apparatus during the determination. A response surface method with an I-Optimal (IV) design was used to optimize and model both terminal and drag coefficient properties. The result obtained from the study for terminal velocity ranges from 5.2 to 11.98 m/s while that for drag coefficient ranges from 0.07 to 0.94. A reduced two factor interaction (R2FI) and reduce linear models was used for modeling data of terminal velocity and drag coefficient respectively. The two models was significant at p<0.01. The R2FI and Optimized values range for design consideration for harvesting machines were Moisture (13.52 - 14%), Weight (150g), Terminal velocity (11.67 - 11.98 m/s), Drag coefficient (0.18 - 0.21), Desirability (0.96 - 1.00). Those for processing and handling machines were Moisture (10 - 10.26 %), Weight (150g), Terminal velocity (7.65 0 8.2 m/s), Drag coefficient (0.42 - 0.44), Desirability (1.00). Finally those for storage structures and machines were Moisture (8%), Weight (150g), Terminal velocity (5.22 - 6.05 m/s), Drag coefficient (0.57), Desirability (1.00).