Production of well-controlled laminar aerosol jets and their application for studying aerosol combustion processes

摘要

Generation of steady-state solid aerosol jets with controllable parameters is often necessary in experimental studies and industrial processes.Most of the current approaches use a fluidized bed to produce an aerosol flow and always introduce initial turbulence into the jet.To produce a laminar aerosol jet,flow straighteners and long tubes are sued that make the design cumber some and inflexible.In addition,in a fluidized bed-type system,the aerosol number density and gas flow rate are inherently interdependent.In a new apparatus described in this paper,metal aerosol is produced using an electrostatic recharging of particles in a DC electric field of a parallel plate capacitor,a so-called electrostatic particulate method.The powder is aerosolized within the capacitor without using any gas flows and only a small velocity,a laminar gas jet is used to carry the aerosol away form the chanber through a small nozzle made in the top plate of the capacitor.It is shown that the aerosol number density is controlled by an electric field,independently of the gas flow rate.The usefulness and flexibility of the new technique for the aerosol combustion studies is demonstrated.Preliminary results on characterization of the produced small-scale,laminar,premixed,lifted aluminum-air flames are reproted.The flame propagation velocities are measured and compared to the earlier results;overall fladimensions and radiation profiles are determined.Individual particle flame zones are visualized in the aluminum-air aerosol flame for the first time.