Aerospace Technic and Technology

The relevance of research on the combustion processes of alkane-based fuels is due to the search for new, efficient, environmentally friendly fuels for the energy and aerospace industries. Paraffin (a mixture of alkanes) is a low-melting material that can be used as an environmentally friendly and high-energy fuel. An important task is to intensify the processes of fuel combustion in the reaction volume. One of the factors of intensification is the electric field. The purpose of this work is to study the laws of the influence of the electric field on the processes of high-temperature heat and mass transfer, melting and burning drops of liquid fuel based on alkanes.

The paper developed a methodology for studying the kinetics of melting and burning of liquid fuel droplets using digital imaging of the object of study and computer processing of the images obtained.

Studies have been conducted on the effect of a uniform electric field on the combustion of alkane particles in the air. The stages of heat and mass transfer in the combustion process are determined. It is shown that the melting of a particle is the main component of the induction period — the time during which the particle ignites. It was revealed that the melting rate significantly decreases if the electric field strength exceeds a certain critical value. It is established that the effect of the electric field on melting is more pronounced at high gas temperatures. It was found that when an octadecane particle melts in an electric field, the unmelted residual solid phase rotates in the melt. It is proved that this is a special case of the Quincke effect.

The kinetics of combustion of octadecane drops of various initial diameters was studied. It has been proven that a linear law of variation of the square of the diameter of a droplet with time (Sreznevsky’s law) is fulfilled in a certain area of burning. The influence of the electric field on the burning rate of particles of different initial diameters was studied. It has been established that under the action of an electric field an increase in the rate of burning of alkane droplets occurs. In particular, for octadecane drops, the burning rate in a constant electric field increases by 10 ÷ 23% depending on the initial diameter of the drop. The burning rate constants of octadecane are found.

The influence of the electric field on the geometric dimensions of the flame is studied. It is established that under the influence of the field the flame becomes asymmetrical and shifts towards the negatively charged plate of the capacitor. This reduces the height of the flame and increases its width. These phenomena are associated with the action of "ion wind" in the flame and the transformation of the energy of the electric field into heat. As a result of the action of these physical mechanisms, the combustion front approaches the surface of the drop, increasing its rate of evaporation.

burning; melting; fuel; engines; alkanes; octadecane; burning rate; electric field; flame

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