某型虚拟冲击器的设计及数值模拟

Design and numerical simulation of a virtual impactor

虚拟冲击器能够吸入空气中的气溶胶并收集特定粒径的颗粒。一般来说,常用的虚拟冲击器的切割粒径较大,工作流量也较大,对于某些限制流量的工况可能不适用。在本研究中,开发了一种新型多缝虚拟冲击器,且喷嘴附近注入清洁空气,能够减小气溶胶在冲击器内的损失。通过数值模拟的方法分析该虚拟冲击器的性能,结果表明,即使总流量为36 L/min,也能获得0.08 atm的低压降,利用具有清洁空气的狭缝喷嘴虚拟冲击器,可将切割粒径降到0.2~0.4μm,并以1.8 L/min的流量收集起来。

The virtual impactor inhales aerosols from the air and collects particulates with specific size.In general,the commonly used virtual impacter has large cutting particle size and works at large flow rate,which may not be applicable to some conditions with limited flow.In this study,a new multi-slit virtual impactor is developed.Its main characteristics are that the impactor can work at high flow rate and low pressure drop.Clean air is injected near the nozzle,which can reduce the loss of aerosol in the impactor.The performance of the virtual impactor was analyzed through numerical simulation.The results show that the cutting particle size of the virtual impactor can reach to 0.2-0.4μm,and the low pressure drop of 0.08 atm can be obtained even if the total flow is 36 L/min.The cutting particle size can be reduced even smaller by using the virtual impactor with clean air with slit nozzles,and can be collected at a flow rate of 1.8 L/min.