Differential Mobility Analyzers (DMA) have been studied for decades to classify a wide range of particle sizes. Its correct behavior is determined by the resolution, influenced by Brownian diffusion losses, distortions in the electric and flow field. The design configuration, especially inlets and outlets, can be a reason of these effects, affecting the DMA reliability. One of these configurations is the tangential inlet for polydisperse aerosol, used in the Vienna-type DMA. The use of a tangential inlet reduces the residence time and favored the aerosol flow distribution in the classification chamber. However, in this configuration swirl effects of non-uniform particle behaviors had previously been observed.

In this work, the 3D-Computational Fluid-Dynamics has been used to analyze the distortions expected of this DMA in previous studies. The proposed methodology had allowed determining its correct operation and thus, to develop new designs optimizing their operation. The procedure includes the simulation by Ansys Workbench v15.0 and the method to determine an adequate behavior, including the effect on the particle distribution and penetration towards the classification chamber, and the effect on the transfer function. The calculation results have allowed the design of alternative geometries of the aerosol inlet keeping the tangentiality. Using the new geometry, the flow distribution has improved removing the flow disturbances, the particle penetration has increased until 15% and the particle distribution has deviated from the ideal one only in a 2% in some cases. The best behavior has been observed especially at high flow rates and lower particle sizes.

数十年来，差动迁移率分析仪（DMA）进行了研究，以对各种粒径进行分类。它的正确行为由分辨率决定，该分辨率受布朗扩散损耗，电场和流场畸变的影响。设计配置，尤其是入口和出口，可能是这些影响的原因，从而影响DMA的可靠性。这些配置之一是在维也纳型DMA中使用的多分散气雾剂的切向入口。切向入口的使用减少了停留时间，并有利于分类室内的气溶胶流量分布。然而，在这种配置中，先前已经观察到非均匀颗粒行为的旋流效应。

在这项工作中，3D计算流体动力学已用于分析先前研究中该DMA的预期失真。所提出的方法允许确定其正确的操作，因此可以开发优化其操作的新设计。该过程包括Ansys Workbench v15.0的模拟确定适当行为的方法，包括对粒子分布和向分级室的渗透的影响以及对传递函数的影响。计算结果允许设计气雾剂入口的替代几何形状并保持切向性。使用新的几何形状，流分布得到了改善，消除了流扰动，粒子渗透率增加到15％，并且在某些情况下，粒子分布仅偏离理想值2％。观察到最佳性能，尤其是在高流速和较低粒径的情况下。