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《Transactions of the Chinese Society for Agricultural Machinery》 2009-01
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Spray Characteristics of PWM-based Intermittent Pulse Variable Spray

Deng Wei1 Ding Weimin2 He Xiongkui1(1.College of Science,China Agricultural University,Beijing 100094,China2.College of Engineering,Nanjing Agricultural University,Nanjing 210031,China)  
pray characteristics are the criteria to evaluate variable spray equipments and the index to analyze the applicability of the equipments.The switching mode solenoid valve was driven by the square signal with the tunable 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.
【CateGory Index】: S491
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