Investigation of Elementary Processes in a Process-Spray at Non-Newtonian Droplets by means of Direct Numerical Simulations

通过喷雾工艺制造的颗粒产品的性能取决于潜在的喷雾特性。喷雾内部的初级雾化和液滴碰撞对颗粒的粒径分布影响很大，从而影响产品的质量。到目前为止，在非牛顿流体中，剪切变薄液滴的碰撞已经得到了广泛的研究，而粘弹性液滴的碰撞是目前研究的重点。本项目的目的是完成这些研究工作。为此，我们将考虑牛顿、粘弹性和部分干燥液滴的碰撞。除了对这些基本过程的基本理解之外，还可以获得这些过程的机理建模的数据。由于现有模型未充分考虑牛顿液滴碰撞过程中的粘性耗散，本文对其进行了研究。一旦建立碰撞模型，将扩展到包括粘弹性流变的影响。抗碰撞稳定性与部分干燥的液滴有关。通过直接数值模拟获得的结果将被纳入机理建模。转移到具有较低细节水平的模拟，例如欧拉-欧拉和欧拉-拉格朗日模拟，可以更好地预测整个过程和产品特性。

The properties of particulate products manufactured by means of spray processes depend on the underlying spray characteristics. The primary atomization as well as droplet collisions inside the spray influence the particle size distribution and thus the quality of the product significantly. Up to now, in the class of non-Newtonian fluids the collision of shear thinning drops have been investigated extensively and first studies have been devoted to the collision of viscoelastic drops. The aim of the present project is to finalize these research works. For this purpose we will consider the collision of Newtonian, viscoelastic and partially dried droplets. In addition to the basic understanding of these elementary processes, data for the mechanistic modeling of these processes can be obtained. The viscous dissipation during the collision of Newtonian drops is investigated, as it is not adequately included by existing models. Once the collision model is developed, it will be expanded to include the influence of viscoelastic rheology. The stability against collisions is relevant for partially dried drops. The findings, obtained by Direct Numerical Simulations, will be incorporated into the mechanistic modeling. The transfer to simulations with a reduced level of detail, such as Euler-Euler and Euler-Lagrange simulations, allow for a better prediction of the overall process and product properties.