This article introduces an algorithm that determines the thermodynamic conditions behind incident and reflected shocks in aerosol-laden flows. Importantly, the algorithm accounts for the effects of droplet evaporation on post-shock properties. Additionally, this article describes an algorithm for resolving the effects of multiple-component-fuel droplets. This article presents the solution methodology and compares the results to those of another similar shock calculator. It also provides examples to show the impact of droplets on post-shock properties and the impact that multi-component fuel droplets have on shock experimental parameters. Finally, this paper presents a detailed uncertainty analysis of this algorithm’s calculations given typical experimental uncertainties.

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

The structure of the relaxation zone behind a shock wave of moderate strength in a mixture of gas, vapour and droplets is analysed. A model is presented for shock induced evaporation, which is based on wet-bulb equilibrium and on the absence of relative motion between droplets and gas. Experimental and numerical data on heterogeneous condensation induced by an unsteady rarefaction wave and on re-evaporation due to shock wave passage are reported for a mixture of water vapour, nitrogen gas and condensation nuclei. Pressure, temperature, saturation ratio and droplet size are experimentally obtained and are very well predicted by a numerical simulation based on the non-linear quasisteady wet-bulb model for phase transition, as well for the expansion wave as for the shock wave. During expansion, droplet number density decays much faster than predicted, which is not yet satisfactorily explained. Shock induced droplet evaporation is studied for post-shock saturation ratios ranging from 5×10−3 to 0.2, corresponding to shock Mach numbers of 1.2 to 1.9. The evaporation times are well predicted by the theoretical model. No evidence is found for droplet break-up for Weber numbers up to 13, and droplet radii of the order of 1μm.

Shock wave structure in a mixture of gas, vapour and droplets

The random choice method applied to non-linear wave propagation in gas-vapour-droplets mixtures

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/pdf/non-linear-wave-phenomena-in-a-gas-vapour-mixture-with-phase-6qnw7jirat.pdf

Non-linear wave phenomena in a gas-vapour mixture with phase transition

Combustion of fog consisting of a hydrogen–air mixture, water vapor, and ultrafine particles of water is studied experimentally. Inflammable fog was generated by sudden expansion of a system “hydrogenair + water vapor”. It is shown that partial condensation of vapor with the formation of microdroplets constricts the flammability limits. Key words: flammability limits, heterogeneous mixtures, rarefaction wave, IR diagnostics.

Flammability Limits for Hydrogen–Air Mixtures in the Presence of Ultrafine Droplets of Water (Fog)

Heterogeneous condensation and evaporation induced by an unsteady rarefaction wave and by the passage of a shock wave in a water‐nitrogen mixture is studied. Time resolved measurements of modal droplet radius, droplets radius, droplet number density, pressure, and gas density are presented. Condensation on Cr2O3‐particles of about 10 nm starts at a saturation ratio of 3.4. Typical droplet radii and droplet number densities are 1.5 μm and 1011 m−3. A shock wave with Mach number 1.36 causes full evaporation in 4 ms.

/pdf/wave-induced-growth-and-evaporation-of-droplets-in-a-vapour-1nxscsnjqp.pdf

de Hc Rick Lange

Papers

Wave induced growth and evaporation of droplets in a vapour-gas mixture