A one-dimensional model has been developed to investigate the thermal decomposition of rocket grade hydrogen peroxide (HP) in a stream of previously decomposed HP products. The model developed assumes steady, one-dimensional adiabatic flow and includes basic mass balances, droplet evaporation, gasphase decomposition kinetics, droplet dynamics, and control volume conservation laws. The code is a...

In the present study, a molecular tagging technique was developed to achieve simultaneous measurements of droplet size, flying velocity and temperature of “in-flight” droplets in a spray flow. Phosphorescent molecules, which can be turned into long-lasting glowing marks upon excitation by photons of appropriate wavelength, were premixed in the water droplets and served as the tracers for the qu...

This contribution explores a droplet actuation mechanism which involves mixing two different liquids slugs in a glass capillary. The resulting contrast in surface tension which arises provides the necessary propulsive power for the droplet. The conceptual idea is demonstrated for an ethanol-water system. The droplet is observed to rapidly reach a peak velocity which then gradually decreases wit...

We numerically study the behavior of self-propelled liquid droplets whose motion is triggered by a Marangoni-like flow. This latter is generated by variations of surfactant concentration which affect the droplet surface tension promoting its motion. In the present paper a model for droplets with a third amphiphilic component is adopted. The dynamics is described by Navier-Stokes and convection-...

Driven by its importance in nature and technology, droplet impact on solid surfaces has been studied for decades. To date, research on control of droplet impact outcome has focused on optimizing pre-impact parameters, e.g., droplet size and velocity. Here we follow a different, post-impact, surface engineering approach yielding controlled vectoring and morphing of droplets during and after impa...

Auto-ignition and combustion of single fuel droplets of methanol, n-heptane and iso-octane are studied. The numerical simulations are based on a detailed vaporization model, a detailed transport model and detailed chemical kinetics. The governing equations of the two phases are solved in a fully coupled way. The influence of different physical parameters like droplet temperature, gas phase temp...

The shape of a dew droplet deposited on the mirror surface of a copper plate was measured accurately using an interference microscope that employed a phase-shift technique. The microscope was constructed by adding a piezoelectric transducer to an interference microscope. A simple method that uses a conventional speaker horn and an optical fibre cable was used to depress any speckle noise. The s...

We investigate the droplet size distributions and concentrations produced by an aerosol generator driven by a high velocity air jet delivered in cross flow to an oil tube at Mach numbers of 0.1-1.0, and Weber numbers based on the air flow parameters between 1000 to 40000. Measured Sauter mean droplet diameters (SMD) from 1μm to 3.5μm were determined by an Electronic Low Pressure Impactor over t...

The Sound attenuation and dispersion in saturated gas-vapor-droplet mixtures with evaporation has been investigated theoretically. The theory is based on an extension of the work of Davidson (1975) to accommodate the effects of transpiration on the linear particle relaxation processes of mass, momentum and energy transfer. It is shown that the inclusion of transpiration in the presence of mass ...

In the present study, an experimental investigation was conducted to quantify the dynamics of the water droplet impact process on a solid surface in order to elucidate underlying physics to improve our understanding of the important microphysical processes pertinent to aircraft icing phenomena. The Reynolds number (Re) and Weber number (We) of the water droplets ranged from Re  1700 to 4900, a...