亚微米虚拟冲击器是实现高灵敏度生物气溶胶光学在线监测的前提，是当前的研究热点之一。基于空气动力学理论与相关研究基础，设计了一种切割粒径为0.4 μm的亚微米级粒子虚拟冲击器，利用计算流体动力学(CFD)分析软件Fluent以及离散相模型对虚拟冲击器结构的入口喷嘴与收集孔间距、收集孔径和流量比等各种设计参数进行模拟与分析，得到了一组优化设计参数并制作了虚拟冲击器实物。测试结果表明，该虚拟冲击器具有良好的浓缩效果，对0.37、0.5、0.7 μm聚苯乙烯乳胶球(PSL)粒子的收集效率等参数与仿真结果基本吻合，验证了流体动力学分析方法的可行性。该虚拟冲击器切割粒径的实验测试结果达到0.4 μm，满足实际应用需求。

A virtual impactor for submicron particles is prerequisite for bio-aerosol optical online monitoring and it is a hot research topic. Based on aerodynamics and past research work, a 0.4-μm-cutpoint virtual impactor is designed with the help of a commercial computational fluid dynamics (CFD) package, Fluent. Discrete phase model (DPM) is applied to simulate and analyze the effect of nozzle-to-collection probe distance, collection probe diameter and minor-to-major flow ratio. The virtual impactor with optimum design parameters is fabricated and tested. According to the experimental results, the virtual impactor can collect 0.37 μm, 0.5 μm and 0.7 μm PSL microspheres efficiently as desired, which proves that the CFD method is practical. Cutoff diameter of the virtual impactor can reach 0.4 μm, which is fit for practical applications.