Research On The Technology Of PWM Variable Sprayer

With the introduction of the precision agriculture and its development in the world, especially in modulation spray system, Author has made the analysis on the problem which the modulation spray system is still faced on. First of all, with the help of the basis knowledge of electronic, a special circus is designed in the job, which can be approved to be useful by simulating in EDA tools. With this drive, an experiment system of modulation spray has been made. A laboratory report by the method of weighting is given here in the paper. Secondly it is have done in this job to do some transient numerical simulation of high speed valve by using CFD software FLUENT, At last author has introduced a simulation manner to simulate the spray pattern of modulation spray system in temporal and spatial, with this mathematical model an analysis job is done in this paper which gives the law of spray pattern of modulation spray system. And the conclusion is here:1) With the circuits in this paper the response speed has been increasing that the rising edge can be cut down to 4.5ms, which is 9ms of trailing edge.2) Using the PWM spray with the circuits in this paper, the flow rate can be calculated by Q = τ×Q_max as the frequency is not higher then 5Hz, when the value is 6.6Hz andthe duty cycle is higher than 60%,it meet the dead zone.3) It is find a 10ms long suction pressure, which will result in air-sucking.4) A 2ms time lapse in open period of the valve have been found in the paper, in this two microsecond, the atomization quality is not so good5) When the valve is opening both the pressure and flow rate meet the maximal level, with two zones which increase sharply.6) A 2ms time lapse is also in the shut down time of the valve. It is also harmfulness for the atomization7) The open and shut down time lapse makes 4ms transition time of a cyclic. In this 4ms the flow rate is increasing with the piston position but not linearity which is increasing quickly to the near maximal value when piston is valve is just opening or closing. As the result of shut down time lapse the actual flow rate will higher then presumption.8) With the movement of piston in the valve the vortex is created, developed and transport to the spray, which will affect atomization.9) As result of the simulation, flat fan nozzle will be better then cone jet. The...