Each impactor contains the majority of ambient fine mass (dp < 2.5 microns aerodynamic diameter) in a bleed flow (minor flow) that is 20% of the total flow entering the virtual impactor.
In some cases, this means that the collected sample is dispersed over a large filter, which can be avoided by use of virtual impactors to concentrate airborne particles into a chamber that is then sampled either by passive deposition or a more active process such as filtering or impinging the minor flow of the virtual impactor (see above).
This increase in size, and therefore mass, ensured the particles had sufficient momentum to pass through the impactors, exiting in the minor flow (5 L/min) in which the particle concentration is enriched by a factor of 10- to 20-fold.
This increase in size and therefore mass ensures that particles have sufficient momentum to pass through the impactors exiting in the minor flow (5 L/min) in which the particle concentration is enriched by a factor of 10- to 20-fold.
Moreover presence of bidirectional flows influences minor flow direction significantly compared to major flow direction.
In minor flow direction, the reduction in walking speeds was observed at capacity.
Evaluations of the aerosol concentrators were performed at different ratios of the minor flow rate to the total flow rate (minor-to-total flow ratios).
A basic design concept in such classifiers is that particles, with larger Stokes number St, follow the minor flow for collection.
Since is the major flow component and is the minor flow component, it may be more effective to considering than the values in the original space.
Intuitively, only needs to be considered because it corresponds to the major flow component and corresponds to the minor flow component or even turbulence.
The characteristic of the main flow force, minor flow force and total flow force are analyzed contrastively, and the experimental results agree well with the CFD results and mathematical model analysis.
