GOALI: Liquid Charging in Electrostatic Atomizers for Coating and Painting Applications

本提案的重点是研究在喷雾器喷嘴处产生电荷的过程。这项工作将与一个工业合作伙伴，喷涂系统公司（SSCo）合作完成，喷涂系统公司是一家大型国际喷雾产品制造商，在芝加哥伊利诺伊大学附近拥有一个设备齐全的研究实验室。这些合作项目已经与上海合作组织进行了持续的合作。提出研究的动机是为了促进涂料和油漆应用的静电雾化器的商业化。这两种应用都将受益于控制滴入轨迹的能力，从而避免浪费，提供精确的沉积，并减少有害物质的扩散。拟议的工作旨在提供实现这些性能特征所需的理解。此外，还将开发一种低成本的计算模型，作为这些雾化器设计的预测工具。该方案包括基于理论、计算和实验的并行研究。这是一个多尺度的问题，将通过理论来解决，将对极薄的近电极极化层的分析（其中存在电荷不平衡）与对更大维度的电中性体流的分析分开。由于这种分离，人们只需要求解不可压缩体流中的拉普拉斯方程（电势）和纳维-斯托克斯方程。通过电极处的边界条件耦合得到Laplace方程和Navier-Stokes方程的数值解。还提出了实验(i)确定电极表面反应速率的经验系数，以及（ii）为计算模型的验证提供数据。将实施验证模型，详细研究各种参数（如电极形状）的影响。与SSCo的合作将为模型验证提供实验数据，并将促进该过程的扩大。更广泛的影响包括工业推广和本科生和研究生的参与；创建演示充电过程的动画。一个成功的非导电液体静电雾化器将为喷雾剂和涂层提供巨大的优势，这些都是我们周围和我们日常生活中使用的材料。

The focus of this proposal is to investigate the process of the generation of electrical charges at the nozzles of sprays. This work will be done in collaboration with an industrial partner, Spraying Systems Company (SSCo), a large international manufacturer of spray products with a well-equipped research lab near the University of Illinois at Chicago. The co-PIs already have an on-going collaboration with SSCo. The motivation for the proposed research is to facilitate the commercialization of the electrostatic atomizers for coating and painting applications. Both of these applications would benefit significantly from the ability to control drop trajectories to avoid waste, provide precision deposition, and reduce the spread of hazardous materials. The proposed work aims at providing the understanding needed to achieve these performance characteristics. In addition, a low-cost computational model as a predictive tool for the design of these atomizers will be developed. The proposal includes concurrent studies based on theory, computation and experiments. This is a multiscale problem that will be tackled by theory to separate the analysis of the extremely thin near-electrode polarized layer, where an imbalance of charges exists, from the analysis of the electroneutral bulk flow with much larger dimensions. As a result of this separation, one would only need to solve for a Laplace equation (for the electric potential) along with the Navier-Stokes equations in the incompressible bulk flow. The solution of the Laplace and Navier-Stokes equations, which are coupled through the boundary conditions at the electrode, will be obtained numerically. Experiments are also proposed to (i) determine an empirical coefficient for the rate of reaction at the electrode surface, and (ii) provide data for validation of the computational model. The validated model will be implemented to conduct a detailed study on the effect of various parameters, such as the shape of the electrode. Collaboration with SSCo will provide experimental data for model validation and will facilitate the scale-up of the process. Broader impacts include industrial outreach and involvement of undergraduates and graduate students; creation of animations demonstrating the charging process. A successful electrostatic atomizer for non-conducting liquids will provide great advantages in sprays and coatings, which are materials that surround us and we use in everyday life.