A Pulse-Width-Modulation-based(PWM-based)continuously variable sprayer was developed using a proportional regulating solenoid valve.Variable flow-rate was obtained by varying the duty cycle of the actuating signal wit...A Pulse-Width-Modulation-based(PWM-based)continuously variable sprayer was developed using a proportional regulating solenoid valve.Variable flow-rate was obtained by varying the duty cycle of the actuating signal with 24 kHz frequency.Flow-rate regulating ranges of the PWM-based continuously variable spray(i.e.the turndown ratio responding to 100%-40%duty cycle)are 7.14:1,3.57:1,and 3.70:1 for flat-fan,hollow-cone and solid-cone nozzles,respectively.The purpose of the study was to evaluate the PWM-based continuously variable spray.The method was to quantify the effects of flow-rate control on spray characteristics in terms of droplet size spectra,spray distribution patterns,and spray angle for flat-fan,hollow-cone,solid-cone nozzles.For all nozzles tested,spray distribution concentrated on the center of the spray field with the decrease of flow-rate.But the spray shape is still symmetrical.The sensitivities of the spray angles to flow-rate were 0.83,0.67,and 0.58(o)/%respectively for flat-fan,hollow-cone and solid-cone nozzles.Compared with the sensitivities of spray angle for PWM-based intermittent variable spray,they are somewhat larger.As flow-rate was reduced from the maximum(100%flow-rate)to the minimum controllable rate,the observed median diameter of spray droplets decreased by 5.4%,9.8%,and 9.9%for flat-fan,hollow-cone and solid-cone nozzles,respectively.This indicates that spray droplet size was affected slightly by flow-rate control.展开更多
文摘A Pulse-Width-Modulation-based(PWM-based)continuously variable sprayer was developed using a proportional regulating solenoid valve.Variable flow-rate was obtained by varying the duty cycle of the actuating signal with 24 kHz frequency.Flow-rate regulating ranges of the PWM-based continuously variable spray(i.e.the turndown ratio responding to 100%-40%duty cycle)are 7.14:1,3.57:1,and 3.70:1 for flat-fan,hollow-cone and solid-cone nozzles,respectively.The purpose of the study was to evaluate the PWM-based continuously variable spray.The method was to quantify the effects of flow-rate control on spray characteristics in terms of droplet size spectra,spray distribution patterns,and spray angle for flat-fan,hollow-cone,solid-cone nozzles.For all nozzles tested,spray distribution concentrated on the center of the spray field with the decrease of flow-rate.But the spray shape is still symmetrical.The sensitivities of the spray angles to flow-rate were 0.83,0.67,and 0.58(o)/%respectively for flat-fan,hollow-cone and solid-cone nozzles.Compared with the sensitivities of spray angle for PWM-based intermittent variable spray,they are somewhat larger.As flow-rate was reduced from the maximum(100%flow-rate)to the minimum controllable rate,the observed median diameter of spray droplets decreased by 5.4%,9.8%,and 9.9%for flat-fan,hollow-cone and solid-cone nozzles,respectively.This indicates that spray droplet size was affected slightly by flow-rate control.
