Simulation of Design and Operational Parameters of Pneumatic Seed Planter for Cotton Using ANSYS Software

The study reports the results of development and performance of pneumatic precision planter to get desired seed spacing and seed rate at real field condition. Computational fluid dynamic software tool was used to optimize design and operational parameters of pneumatic seed metering mechanism. Vacuum pressure and cell diameter were simulated for cotton seeds through ICEM CFD software and precision pneumatic seed planter was developed. Aerodynamic properties like maximum terminal velocity and drag coefficient of cotton seed were found to be 8.91ms⁻¹ and 0.63, respectively. Analytically it was proved that, the suction pressure is directly proportional to seed density, geometric mean diameter, square of air flow rate and inversely proportional to distance between seed position and cell. Reynolds number was determined and found that air flow is turbulent, hence Navier-Stokes equations were solved using standard k-ε turbulence model. Results of simulation showed that optimum vacuum pressure, rotor speed and cell diameter for cotton were 2.72 kPa, 0.81 ms⁻¹ and 2.66 mm, respectively for third seed metering model (SMM3). The predicted responses of miss index, multiple index and precision index were 6.76, 3.89 and 10.81 percent, respectively with combined desirability of 0.88 for the SMM3 model. The optimum vacuum pressure and cell diameters were derived from simulation study and a cotton precision planter was developed considering additional factor of safety to overcome tractor vibration and air leakage of mechanical components of seed metering mechanism. The simulation results were validated by testing developed metering unit under lab setup using instrumented test rig and was also evaluated for cotton planting under actual field conditions.