MIXING EFFICIENCY ESTIMATION BY PROBE BREACKDOWN FLUORESCENCE

摘要

The effect of the mixing actuation in compressible flow is observed because of the gasdynamic instability arisen after the long filamentary pulse discharge generation along the contact zone of two co-flown gases. The mixing efficiency is examined qualitatively and quantitatively by means of Probe Discharge Breakdown Fluorescence (PBF). The result of interaction of a pulsed filamentary discharge with a surrounded gas strongly depends on the discharge decay mechanism, which is a function of the discharge electrical and geometrical parameters. At adequate high power deposition (no exact criteria currently), the turbulent gas motion develops in a cooling post discharge channel. As a result, the rate of expansion of after-discharge channel and intensity of small-scale gas movement in vicinity of disturbed zone increase considerably. The turbulent motion arisen in the immediate vicinity of boundary between two gases may significantly enhance of mixing, which can be used to control the mixing rate in high speed directly fuelling combustors. In recent experiments [2-3] it has been shown that there is fast unconventional mechanism of the afterspark channel expansion. The expansion is driven by high velocity radial jets formed during the afterspark channel development. It cannot be described by the conventional model of turbulent expansion. The second discussed idea is the filamentary discharge localization and movement in medium at gradient concentration of two dissimilar components. It is considered that the interaction can be controlled thoroughly, because the discharge position and dynamics in mixing layer enable to be steered by the discharge parameters and physical properties of the gases.