| Simultaneous particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) of CH in turbulent jet flames are used to provide new insights into jet flame dynamics and jet flame stabilization.; In attached turbulent non-premixed flames in coflow, the location of the CH layer is found to correspond well with the location of the stoichiometric velocity, US, and also with high strain rate zones; however, significantly higher values of the maximum strain rates, compared to the mean value, are frequently observed. The residence time in the CH layer remains nearly constant with axial distance downstream. The mean value of the maximum principal strain rate is observed to decrease along the axial direction and shows a good correlation to a S ∼ ( x/d)−0.7 relation for a wide range of jet Reynolds numbers.; Flame lengths of jet flames in crossflow and deflected jet flames increase as the injection angle increases due to the reduced entrainment. The correlation between the velocity on the CH layer, UFlame, and US is good at the wind-ward side, while it is not as distinct at the lee side of the jets. Contrary to attached jet flames in coflow, a large dilatation is observed on the flame surface, which is thought to be a result of the premixed characteristics inherent to jet flames in crossflow.; The transition from flame lift-off to blow-out of a non-premixed turbulent jet flame is observed by comparing a stably lifted flame with a lifted flame near blow-out. Instantaneous images show the divergence and deceleration of the flow at the flame base which is characteristic of a leading edge flame. The width of the flame base is found to be wider when the flame is near blow-out and the axial velocity near blow-out is higher when compared to a stably lifted flame. These observations are consistent with numerical studies of the laminar triple flame. Accepting the leading edge flame as the flame stabilization mechanism, a simple blow-out mechanism is proposed. |
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