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Analysis and modelling the coating of solid particles

固体颗粒涂层的分析和建模

基本信息

批准号：
336370664
负责人：
Professor Dr.-Ing. Martin Sommerfeld
金额：
--
依托单位：
Institut für Verfahrenstechnik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/336370664?language=en
关键词：
Analysis modelling coating solid particles

项目摘要

In the frame of the research project it is planned to analyse the fundamentals and to derive models for the collision of droplets with larger solid particles and their coating for Euler/Lagrange calculations. The elementary process of collisions between droplets and larger solid particles will be analysed experimentally using imaging techniques. For that purpose a droplet chain will be produced into which solid particles are shot with defined velocity and frequency. As a result of the collision of droplets with larger particles one may observe bouncing, deposition or disintegration. The collision event will be visualised using high-speed cameras and illumination by LED-arrays and a laser. The results will be analysed by image processing. For all the relevant parameters of influence it is first required to determine the outcome of the collision and summarise them with respect to the important non-dimensional numbers, e.g. Ohnesorge-number and impact Reynolds-number. The considered parameters of influence are the size ratio (droplet/particle), droplet liquid properties (viscosity and surface tension), particle properties (temperature and surface roughness), impact velocity and impact location of the droplet on the particle surface (i.e. central and lateral impacts). As mentioned before, the droplets are smaller than the particles and the liquid is wetting. All these effects need to be considered for deriving physically-based boundaries between the collision outcomes using the relevant non-dimensional numbers. For the regime splashing or partial deposition the size distribution of the droplet fragments also will be analysed and modelled.The next step is the experimental determination of the dimensions of the final liquid film on the particles, including film thickness and lateral dimension of the film. For that purpose the droplet liquid will be doped with fluorescing dye in order to allow a better distinction from the image of the particle. For the development of the coating model with respect to the impact conditions and the relevant non-dimensional numbers, physically based correlations shall be developed.In addition, for analyzing the collision outcomes, theoretical studies will be conducted based on an energy balance. The liquid film formation on the particle will be studied based on film theory.The developed coating model, which considers a broad range of parameters and also for the first time lateral impact, will be derived for being used in the frame of Lagrangian calculations of technical coating processes.

在研究项目的框架内，计划分析基本原理，并推导液滴与较大固体颗粒及其涂层的碰撞模型，用于欧拉/拉格朗日计算。将使用成像技术对液滴与较大固体颗粒之间碰撞的基本过程进行实验分析。为此，将产生一个液滴链，固体颗粒以规定的速度和频率射入其中。由于液滴与较大颗粒的碰撞，人们可以观察到反弹、沉积或解体。碰撞事件将使用高速摄像机以及LED阵列和激光照明来可视化。结果将通过图像处理进行分析。对于所有相关的影响参数，首先需要确定碰撞的结果，并针对重要的无量纲数，例如Ohnesorge数和Impact Reynolds数对它们进行汇总。考虑的影响参数包括液滴尺寸比(液滴/颗粒)、液滴液体特性(粘度和表面张力)、颗粒特性(温度和表面粗糙度)、液滴在颗粒表面的撞击速度和撞击位置(即中心撞击和横向撞击)。如前所述，液滴比颗粒小，液体是湿润的。在使用相关的无量纲数确定碰撞结果之间的物理边界时，需要考虑所有这些影响。对于区域溅射或部分沉积，还将对液滴碎片的尺寸分布进行分析和建模。下一步是实验确定颗粒上最终液膜的尺寸，包括液膜厚度和液膜的横向尺寸。为此，将在液滴液体中掺入荧光染料，以便与颗粒的图像更好地区分开来。为了建立关于碰撞条件和相关无量纲数的涂层模型，应建立基于物理的关联。此外，为了分析碰撞结果，将基于能量平衡进行理论研究。基于液膜理论研究了颗粒上液膜的形成过程，建立了考虑各种参数的液膜模型，并首次在拉格朗日计算的框架下对工艺涂层过程进行了计算。