摘要
采用频率在20 Hz以内可调、占空比可调的方波信号驱动开关电磁阀,改变电磁阀门开通和关断的时间,实现了基于脉宽调制(PWM)技术的间歇式脉动变量喷雾。以农业喷施中常用的平口扇形喷嘴为例,从间歇式脉动变量喷雾的流量调节范围、雾量分布、喷雾角、雾滴粒径、雾滴速度及喷雾动态特性随流量的变化规律等方面,分析讨论了PWM间歇式脉动变量喷雾的雾化特性。研究结果是,流量调节范围为4.17;随流量的减小,雾量分布向中央集中的趋势很小,雾滴粒径稍增大,喷雾角、雾滴粒径随流量的变化率分别为0.043 3(°)/%、0.616μm/%,影响程度很微小;随流量的减小,雾滴速度基本无变化,动能中值直径(KEMD)和比能(SE)随流量的变化率分别为-0.63μm/%、0.245 1 J/(kg.%),流量控制对喷雾动态特性的影响也较小。
Spray chara the applicability with the tunable cteristics are the criteria to evaluate variable spray equipments and the index to analyze of the equipments. The switching mode solenoid valve was driven by the square signal duty cycle and the adjustable frequency within 20 Hz. Through changing the turn-on and turn-off time of the valve, the intermittent pulse variable spray based on pulse width modulation （PWM） was realized. Taking flat-fan nozzle commonly used in agriculture as an example, the spray characteristics of PWM-based intermittent pulse variable spray were discussed in the aspects of the change rules of flow adjusting range, spray distribution pattern, spray angle, spray droplet size, droplet velocity and spray dynamic characteristics with flow changing. The results of flow adjusting range is 4.17 ; spray distribution pattern has small tend to concentrate toward the spray center and the spray droplet size decreases slightly when the flow-rate reduces. The change rates of spray angle and spray droplet size with the flow change are 0. 043 3 （ ＊）/% and 0. 616 μm/%. It indicates the effects are all very trivial. Spray droplet velocity nearly has no change with the flow decreasing. And the change rates of kinetic energy median diameter （KEMD） and specific energy （SE） with flow change are -0.63 μm/% and 0.245 1 J/（kg· %） respectively. It also indicates that spray control has less impact on spray dynamic characteristics.
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2009年第1期74-78,共5页
Transactions of the Chinese Society for Agricultural Machinery
关键词
雾化特性
变量喷雾
脉宽调制
Spray characteristics, Variable spray, Pulse width modulation
