Correctness of probe withdrawal of samples in flames

Studying RDX and HMX combustion mechanisms by various experimental techniques

“…Certainly, the sampling near the burning surface becomes more representative in the case of intense heat release in the c-phase, because the destruction of the local wave structure is not so fatal for the c-phase processes in this case. Still, the question of what exactly is sampled in the region at a distance smaller than 100 μm from the surface is open, because the problem considered in [32] is inapplicable to the case with a gasifying surface inside the domain Δ.…”

“…Thus, when approaching the burning surface, the sampler takes the gas from an approximately 100 μm zone in front of the sampler. It is important to know beforehand which zone governs the combustion process: if the responsible zone is the gas phase, then the gas sampling from the governing zone leads to cardinal destruction of the combustion process, because the condensed phase is devoid of heating on an area greater by more than an order of magnitude than the area of the sampler tip (see [32] for α ≈ 100). Unfortunately, it is such a situation that occurs in studying the RDX and HMX combustion zones at atmospheric (and subatmospheric) pressure.…”

“…The calculated results were plotted in Fig. 3 in [32]. That figure showed the sampling zones with the relative sampling power α = 200 and 10.…”

“…Because of the strong dependence of the degree of conversion on r, the spatial resolution of sampling (Δ) was only insignificantly different from z 0 . Such a consideration of the problem showed [32,[23][24][25][26] that the following relations are valid:…”

“…What has to be sampled and from which part of the flame it should be sampled are the issues considered in detail in [23][24][25][26]32]. The problem of gas sampling from an isothermal flow of the mixture with the degree of conversion increasing along only one spatial coordinate Z was solved theoretically in [32]. The sampler was approximated by a disk drain of radius R and power q.…”