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The vaporisation frequency response due to pressure oscillations is analysed for a spray of repetitively injected drops into a combustion chamber. In the Heidmann analogy, this vaporizing spray is represented by the so-called ‘mean droplet’, which is a continuously fed spherical droplet at rest inside the combustion chamber. Only radial thermal convection and conduction effects are considered inside the vaporizing mean droplet since the feeding is realized symmetrically with the same liquid fuel, using a point source placed at the centre. This feeding process, at some liquid-liquid heat transfer coefficient, is now considered as a proper boundary condition of the generalized feeding regime, which controls the whole fuel injection process into the chamber. Effects due to the variation of the heat transfer coefficient are analysed for the evaporating mass response factor, calculated on the basis of the Rayleigh criterion. A chaotic response is especially noticed in the process when the heat transfer coefficient is fixed at unity.
We examine cases of stationary vortices that can appear inside spherical liquid drops. The first case is that of an incompressible external flow of uniform speed at infinity, leading the liquid in the drop by friction to form a Hill vortex. In the second case, the external fluid does not interact by friction with the liquid, but the drop is subjected to an axial temperature gradient causing a variation in surface tension. This time it is the induced movement which entrains the internal liquid. Note that the two situations can lead to the same Hill vortex. Combined effects are envisioned. We are also interested in the time factor in these phenomena.
In this short article, we give a summary of combustion-based weapons and their effects. Flame throwers and thermobaric weapons, bombs: napalm, explosive devices, phosphorus bombs are mentioned. Then it comes to missiles, the space army and weapons pollution.
The macroscopic balance equations of the fluid interfaces were established by considering two scales of length and by means of some approximations, such as the conservation of the mixed velocity vector and of the gradient parallel to the crossing of the interfacial zone. We generalize this method to the case of four-interfaces in the presence of electromagnetic fields. The transition to space-time is indeed a means of obtaining a homogeneous presentation of the balance sheets.
