Aerosol formation in an isothermal stagnation flow

Abstract

An experiment has been performed in a laminar stagnation point flow in which two non-premixed reactants produced an aerosol of sub-micron particles. The reactants were NH3 and HCl. The rate of mixing of the reactants was determined by the velocity gradient or strain rate of the flow; the response of the aerosol dynamics to the flow field was measured with a laser light scattering technique. Laser Doppler Spectroscopy was used to measure the particle size. It was found that the particle size was independent of the strain rate of the flow. On the other hand, the particle number density decreased as the strain rate increased. It is argued that the intensity of light scattered from the aerosol is, therefore, a measure of the amount of product of the relatively slow NH3-HCl reaction.