Aerobreakup in Rarefied Supersonic Gas Flows (Keynote)

We present new experimental results on the interfacial instabilities and breakup of Newtonian liquid drops suddenly exposed to rarefied, high-speed (Mach 3) air flows. The experimental approach allows for the first time detailed observation of interfacial phenomena and mixing throughout the breakup cycle over a wide range of Weber numbers. Key findings are that Rayleigh-Taylor instability alone is the active mechanism for free stream Weber numbers as low as 28 for low viscosity liquids and that stripping rather than piercing is the asymptotic regime as We→∞. This and other detailed visual evidence over 26 < We < 2600 are uniquely suitable for testing CFD simulations on the way to basic understanding of aerobreakup over a broad range of conditions.