为了研究荷电雾滴群撞击植株靶标界面的过程,研究了适合撞击过程测量的相位多普勒粒子分析仪(PDPA)测试方法,分析了荷电雾滴群撞击界面后形态特征及形成的原因。实验结果表明:荷电雾滴群特殊的空间运动结构决定其撞击植株靶标界面后具有独特的存在形态;荷电雾滴撞击界面后只会产生粘附或反弹而不会发生喷溅;较多细微雾滴的存在导致荷电雾滴群反弹后凝并现象显著,使雾滴的粒径增大而个数减少;单雾滴撞击界面后产生粘附或反弹的判据K的临界值不适于荷电雾滴群的撞击过程,而法向Weber数为30可作为发生反弹现象的参考依据;较大的切向速度能够造成荷电雾滴撞击植株界面后反弹现象的发生;荷电雾滴所具有的部分法向动能在撞击反弹过程中转为切向动能。
In order to study the process of charged droplets impacting the plant target interface, a test method by using PDPA was given. Both the morphological characteristics of charged droplets after impact and its causes were analyzed. The measurement results indicated that the special space movement form of charged droplets determined their unique morphological characteristics after impact. Charged droplets after impact would adhere to the interface or rebound but never splash. The existence of more fine droplets made coalescence phenomenon remarkable so as to increase the charged droplet size but decrease their number. The critical value of K for determing a single droplet' s adhesion or rebound after impact was not suitable for the process of charged droplets impacting the plant target interface. However, 30, the critical value of normal Weber number,could be a reference for determing charged droplets' adhesion or rebound after impact. Larger tangential velocity may encourage charged droplets to rebound from the interface after impact. A part of normal kinetic energy of charged droplets would translate into tangential kinetic energy after impact.