远射程风送式喷雾机的雾滴空间传输机理及协同增效机制

Research in the long-range air-blast spraying field was focused on optimization of structure, droplet deposition, droplet drift and recovery. But the mechanism of droplet transfer in space wind is not yet clear. It was found in experiment that the spraying range of air-blast sprayer was affect by mixing some additive to the spraying solution. However, it still needed to be further and depth studied that the increasing efficiency mechanism of air-blast spraying by using some additives. The ultimate goal of this study is to solve the existing problems such as high energy consumption in long-range air-blast sprayer. In this study, air-blast spraying droplet will be used as research objects while methods of aerodynamics, fluid dynamics and finite element analysis will be utilized to carry out the analysis of air-blast sprayed droplets’ in-the-space movement, thus to construct the in-the-space motion models for air-blast sprayed droplets. Changes of the droplet load and its characteristics within the wind field will be studied to reveal the breaking down and aggregating laws during a droplet’s transmission in the space. The mechanism of droplet movement in the air-blast status will be studied to clarify the dynamics principle for reducing droplet rupture and its transmission resistance. Better pesticide solution additive formulations will be filtered out by studying the mechanism of using pesticide solution additives to reduce transmission resistance. Furthermore, it can provide methods for improving the efficiency for air-blast sprayed droplets during their transmission in the space. Theoretical basis of the engineering research as to improve efficiency for air-blast spraying will be established along with the studies, and hereby to provide the basis for air-blast sprayers’ high efficiency and low energy consumption applications. The research will be important implications to the air-blast spraying technology application.

对远射程风送式喷雾机的研究集中在喷雾机结构的优化、雾滴沉积、雾滴飘移及回收方面，但雾滴在空间风场中的传输机理尚未明确；申请者在试验中发现，药液中加入药液添加剂会影响风送式喷雾机的喷程，然而，这种减阻增效的机制有待深入探究。本项目旨在通过对风场中雾滴流的运动机理研究，探索远射程风送式喷雾机降低能耗的途径；拟采用空气动力学、流体力学及有限元分析方法，研究风场中雾滴的受力，建立风场中雾滴的空间运动模型；研究风场中雾滴特性参数的变化规律，揭示雾滴在空间传输过程中的破裂与聚合的规律，阐明风送式喷雾中减小雾滴破裂与传输阻力的动力学原理；研究添加剂、农药剂型及风速对减小雾滴传输阻力的协同增效机制，提供风送式喷雾技术雾滴空间传输中的增效方法；为远射程风送式喷雾机的节能增效工程研究奠定理论基础，为其高效低耗应用提供理论依据。研究成果对风送式喷雾雾滴传输节能增效的技术应用具有重要的科学意义。

风送式喷雾技术是联合国粮农组织推荐的一种先进高效的施药技术，但雾滴在空间风场中的传输机理尚未明确，基于此，本项目针对以下内容开展研究并获得了重要结果：.建立了淹没气-液两相流射流空间流场模型并进行了验证，湍流模型选用标准的k-ε方程，并考虑重力对雾滴流的影响；风场中雾滴流运动仿真选用离散相模型，空心锥雾喷嘴选用离散相模型中的压力-旋转喷嘴雾化模型；外部流场划分为疏密不同的网格；归一化处理了数值计算与田间试验两组数据间数量级的差异，卡方检验结果表明本项目研究所选用的数值计算模型可信。.研究了风场中雾滴的运动特性，获得了雾滴在风场中运动速度的三维矢量表达式：.vx=4.913x2-16.2910x+31.964；vy=0.1485x2-0.5825x+0.2787；vz=0.6739x2-2.2716x+2.956。.阐明了风场中雾滴粒径的变化机理：近出风口处高速气流对雾滴的破碎使得雾滴粒径变小；中速气流作用下，雾滴柱中存在卷吸现象，一些雾滴在前行过程中发生聚合而形成大粒径的雾滴；低速气流使雾滴扩散弥漫，蒸发的作用而使雾滴粒径变小；小粒径雾滴在气流的作用下传送得更远；雾滴粒径平均值的变化规律为dxavr=-0.0151x3+0.6075x2-10.983x+245.7。.研究了喷雾液的张力和粘度对雾滴特性参数的影响，降低液体表面张力可以细化流场中雾滴粒径，雾滴沉积量随液体表面张力降低而减少；增加液体粘度可以使流场中的雾滴粒径变大且有助于降低雾滴密度；液体粘度对雾滴速度无明显影响；发明了雾滴浓度检测系统，填补了雾滴浓度测量技术的空白。.本项目建立的淹没气-液两相流射流空间流场的数值计算模型及归一化处理数据的验证方法，可为将来远射程风送式喷雾机设计及节能减损技术研究提供理论依据。