Effect of initial pressure on the propagation characteristics of supersonic turbulent jets in fuel jet ignition

Abstract

The effects of initial pressure (Pini) on the propagation characteristics of supersonic turbulent jets (STJ) were studied experimentally in a constant volume chamber. Based on the top vortex motion, three types of flame propagation modes are identified: Mode 1, the vortex in the middle of the jet propagates; Mode 2, the vortex in the middle of the jet moves to the top and the tail; Mode 3, jet tail flame extinguished. Each mode follows a 3-stage propagation method: (a) a jet flame with a with a sharp drop in the flame tip velocity (VFTV); (b) a self-accelerating mushroom-shaped flame followed by turbulent flame with low frequency oscillation; (c) a turbulent flame with a drop in VFTV. The momentum dissipation causes the velocity to drop in stage I and stage III, and stage II is controlled by the eddy motion of the mushroom-shaped flame tip and the pulsation of the flow field. The experimental results show that higher Pini can stimulate a stronger interaction mechanism between flow field oscillation in the main combustion chamber (MCC) and chemical heat release oscillation in the pre-chamber (PCC). Based on an evaluation of the model correlations, we found that the jet penetration length showed a linear relationship with the product of the relative pressure fourth root and the time square root.