Shock-induced behavior in micron-sized water aerosols

Abstract

We have developed a suite of tools for studying aerosols behind shock waves. A Mie-extinction particle sizing diagnostic and a computational model, along with a specially designed square-section shock tube were developed to study the time-history of micrometer-sized aerosols behind shock waves. These tools are critically needed to pursue the use of shock tubes to study the combustion behavior of low-vapor-pressure fuels. While the facility is designed to study reactive systems, we began by measuring the behavior of water aerosols in the range of 1 -10 m behind shock waves with temperatures between 450 and 600 K and pressures between 0.64 and 1.1 atm. From these data we determined evaporation rates and found a correlation that provides the noncontinuum evaporation rate in terms of the d 2 evaporation rate and a correction function.

Modeling of particle cloud dispersion in compressible gas flows with shock waves

“…In this case, the shock-spray interaction can change dramatically the dispersion of droplets, leading to the change in the mitigation capacity of the spray system. [17][18][19] On the contrary, the particle cloud can also affect the propagation of the shock wave. 20 Basically, as a result of the high velocity of the shocked gas, the shock-droplet interaction can generate complex coupled phenomena such as droplet deformation, atomization, collision, coalescence, and evaporation.…”

AEROFROSH: a shock condition calculator for multi-component fuel aerosol-laden flows

“…Hanson and Davidson used an aerosol shock tube to study the interaction of liquid aerosols with shocks and developed a computer code that correctly predicted the time evolution of evaporating droplet diameters [57][58][59][60]. Fuel loading in their shock tube was accomplished by generating aerosols with ultrasonic nebulizers and then pulling this particle-laden gas into the tube through poppet valves in the endwall.…”

“…Conventional gas-phase shock tubes use a manometric method of determining the fuel concentration prior to experimentation. In contrast, shocks in aerosols require a fuel measurement after droplet evaporation is complete, because techniques of quantifying the amount of fuel aerosol in the Region 1 mixture (e.g., using Mie scattering [60]) are difficult. (Note that in shock tubes that employ aerosol injection systems [37,38], simply measuring the volume of liquid that is injected is possible; however, nonuniformity in the aerosol concentration throughout the shock tube and losses of aerosol to the tube walls make this technique less reliable.)…”

Information content of scattering measurements and characterization of spheroids

“…This method involves the analysis of the dependency among the kernel functions (i.e., the Mie extinction/scattering coefficients) and has been demonstrated to minimize the number of measurements and reveal the optimal wavelengths and angles to perform the scattering measurements. Such results have provided valuable insights into the design of particle/aerosol diagnostics based on wavelength-multiplexed extinction (Ma & Hanson, 2005;Hanson, Davidson, & Hanson, 2007). However, many applications involve characterizing the shape and SDF of non-spherical particles, to name a few, remote sensing of the interstellar dusts (Wickramasinghe, 1991), detecting airborne biological agents (Duncan & Thomas, 2007), and monitoring energetic nanoparticles (Mang, Hjelm, Son, Peterson, & Jorgensen, 2007;Yang, Sun, Wang, & Dlott, 2003).…”