Dmitrii O. Glushkov

Numerical Investigation of Water Droplets Shape Influence on Mathematical Modeling Results of Its Evaporation in Motion through a High-Temperature Gas

The numerical investigation of influence of a single water droplet shape on the mathematical modeling results of its evaporation in motion through high-temperature gases (combustion products of a typical condensed substance) has been executed. Values of evaporation time, motion velocity, and distance passed by various droplet shapes (cylinder, sphere, hemisphere, cone, and ellipsoid) in a high-temperature gases medium were analyzed. Conditions have been defined when a droplet surface configuration affects the integrated characteristics of its evaporation, besides temperature and combustion products concentration in a droplet trace, insignificantly. Experimental investigations for the verification of theoretical results have been carried out with using of optical diagnostic methods for two-phase gas-vapor-liquid flows.

Transient Heat and Mass Transfer of Liquid Droplet Ignition at the Spreading over the Heated Substrate

The processes of heat and mass transfer accompanied by phase changes and chemical reactions are numerically modeled for the ignition of a liquid droplet formed from a condensed substance hitting the surface of a high-temperature metallic plate (substrate). The time delay of a droplet ignition is determined as well as the influence scope of a substrate, droplet, and oxidizer temperature, together with sizes and speed of droplet spreading on the ignition response. Conditions are revealed when spreading and deformation of a liquid droplet dominate during the ignition process.

Numerical and Experimental Research of Heat and Mass Transfer at the Heterogeneous System Ignition by Local Energy Source with Limited Heat Content

Numerical and experimental investigations were executed for determination of macroscopic regularities of heat and mass transfer processes under the conditions of the phase transformations and chemical reaction at the ignition of vapors coming from fabrics impregnated by combustible liquid into oxidant area at the local power supply. It was established that initial temperature of local energy source and volume fraction of combustible liquid vapors in fabric are necessary for realization of ignition conditions in a system “fabric—combustible liquid—oxidant.”. Thus three ignition modes are possible for such system. The most widespread mode is an arrangement of ignition zone near the lateral side of local energy source. Also we obtained approximating expressions of ignition delay time on initial temperature and characteristic size of a local energy source for fabrics impregnated by some kinds of combustible liquids (gasoline, kerosene, and diesel fuel). Its dependences may be useful at engineering calculations of fire danger for processes of single hot particles interaction with liquid combustible substances.

Research of Macroscopic Regularities of Heat and Mass Transfer at the Ignition Condition of a Liquid High-Energy Material by an Immersed Source with a Limited Energy Capacity:

We carried out a numerical and experimental investigation of heat and mass transfer at the ignition condition of a liquid high-energy material by a typical immersed source with a limited energy capacity, being a small, intensely heated metallic particle. The numerical research is made on the basis of a model taking into account a group of interrelated physicochemical processes (thermal conductivity, diffusion, convection, mixing, and radiative heat transfer) with phase transitions (evaporation of the liquid and crystallization of the particles material). We established such terminal conditions for the immersion energy source that prevent inflammation of the high-energy material.

Mathematical Modeling of Heat and Mass Transfer Processes with Chemical Reaction at Polymeric Material Ignition by Several Small-Size Hot Particles

Numerical research of interconnected heat and mass transfer processes in the “two hot particles—polymeric material—air” system was executed. The joint effect of several local heat sources on the main integrated characteristic of ignition process (ignition delay time) was established. Two ignition models characterized by the relative positioning of hot particles on a polymeric material surface were revealed. Besides, there were established characteristics of local heat sources and the distance between them (700  K and or  K and when regularities of heat and mass transfer processes in the “two hot particles—polymeric material—air” system are similar to regularities of heat and mass transfer processes in the “single hot particle—polymeric material—air” system.

Numerical Study of Heat and Mass Transfer at the Ignition of Condensed Substances by Hot Particles

Mathematical models of ignition of condensed substances considering interconnected processes of a heat and mass transfer in systems “composite propellant – hot particle – gas”, “liquid fuel – hot particle – air” and “gel-like fuel – hot particle – gas” were developed. As a result of numerical modeling modes of ignition for solid, liquid and gel-like condensed substances characterized by ignition delay time and arrangement of ignition zone relative to local energy source were established. Liquid fuel has 3 ignition modes, composite propellant and gel-like fuels have 1 ignition mode

Mathematical modelling of low-temperature ignition of small-sized coal particles

Physical and predictive mathematical models of small-sized coal particles ignition in the conditions of rather low temperatures (less than 500 K) were developed. The model considers the interconnected processes of heat transfer in a particle and surrounding gas area, thermal decomposition of coal, diffusion of coal decomposition products (volatile components) and its oxidation reaction, warming of coke part (carbon) and its heterogeneous ignition. Mechanisms of volatile components gas-phase ignition and coke part of a coal particle heterogeneous ignition were investigated. The limit conditions for possible ignition of coal dust particles at rather low temperatures were determined according to the results of the executed numerical modeling. Approximating mathematical expressions for forecasting of low-temperature ignition characteristics of coal particles at the objects of industrial power engineering were formulated.