Comparison of the characteristics of micro-explosion and ignition of two-fluid water-based droplets, emulsions and suspensions, moving in the high-temperature oxidizer medium

摘要

Disintegration of intensely heated liquid droplets often occurs in the mode of puffing and micro-explosion. The efficiency of many gas-vapor droplet technologies can be significantly increased by the rational and controlled use of the effects of dispersion and explosive breakup of the initial droplets. They are often called parent drops. This paper presents the results of experimental studies of fragmentation of boiling-up two-component drops with different composition and structure: emulsions, suspensions, and non-mixed two-liquid drops. The methods of energy supply to the drop by enhancing the convective and radiative heat transfer, close to the real technologies of fuel ignition, were used. The conditions of free fall of inhomogeneous droplets were considered to exclude the influence of holders on their heating and cooling (heat outflow) during the time spent in the combustion chamber. The characteristics of the main heat and mass transfer processes and phase transformations, providing a regime of intense partial fragmentation, as well as the production of aerosol at the droplet micro-explosion, have been determined. When registering micro-explosion, the times of droplet heating before the breakup, the number and size of child-droplets, the ratio of the evaporation surface area before and after disintegration were controlled. The solid particles in the composition of suspension droplets are shown to significantly intensify the processes of heating, micro-explosive break-up and subsequent ignition. The results of experiments carried out in wide ranges of temperature, velocity and droplet size were considered to apply the obtained data to fuel combustion models at different aero- and gas-dynamic conditions.