Effect of Vane Shape on Fertilizer Distribution for a Dual-Disc Spinner Spreader

Abstract

Abstract.Spinner-disc spreaders are commonly used for application of granular fertilizers with components (divider, spinner-discs, and vanes) influencing material flow behavior and distribution. Fertilizer ricocheting off these components is an uncontrolled aspect of material flow that negatively impacts spread uniformity. Therefore, an investigation using potash (KCl) was conducted to understand the impact of vane shape on fertilizer flow, ricocheting and distribution for a dual-disc spinner spreader. Four different vane shapes were used in this study. The first two vanes (Vanes 1 and 2) were common to this type of spinner spreader with a tapered and open-faced design. However, Vane 1 had a forward tapered top edge at an angle of 32° while Vane 2 had a top edge that was tapered backwards at 15°. Vanes 3 and 4 both had C-channel cross sections with Vane 3 tapered from inside out but Vane 4 had a constant height. Treatments included application rates of 220 and 440 kg/ha using three spinner disc speeds (600, 700, and 800 rpm). Stationary tests were conducted using a collection device that mounted around the spinner discs and vanes in order to estimate fertilizer particle exit points off the vanes. Standard pan tests were conducted to characterize resulting spread patterns, effective spread width, and spread uniformity. Results indicated that the level of ricocheting was significantly impacted by top edge design of a vane and increased with disc speed. The forward, upward facing top edge of Vane 1 caused on average, 26% of the material flow to be ricocheted by the vanes thereby inducing an uncontrolled nature of spread. However, the rearward facing top edge of Vane 2 reduced ricocheting by 13% plus generated a backward particle rotation for those contacting it. The majority of ricocheting occurred when particles contacted the vanes compared to the spinner discs. Ricocheting generated an uncontrollable aspect of the spread pattern with these particles applied along the centerline of the spreader. The effective spread width increased with disc speed. All four vane shapes generated equal effective spread widths of 18.3 and 21.3 m at 600 and 700 rpm, respectively. However, at 800 rpm, Vane 4 generated the greatest effective spread width of 24.4 m compared to 22.9 m for the other three vanes. The wider spread width for Vane 4 was contributed to the rectangular U cross-section maximizing the horizontal velocity of potash particles when exiting the vanes compared to the other three, more open faced vanes. Finally, the spread uniformity varied by vane shape with Vane 2 consistently generating the lowest CVs. Keywords: Distribution, Ricocheting, Vane Design, Spread uniformity, pattern.