Ignition by Multiple Jets

Abstract

The main reason that hot turbulent jet ignition has become attractive to gas engine manufacturers is that hot jet ignition can achieve faster burn rates due to the ignition system producing multiple, distributed ignition sites, which has greater likelihood igniting a lean mixture compared to spark ignition. This leads to better thermal efficiency and low NOx production. Compared to conventional spark ignition, a hot jet has a much larger surface area leading to multiple ignition sites on its surface which can enhance the probability of successful ignition and cause faster flame propagation and heat release. Over the last few decades, pre-chamber jet ignition had technologically advanced from conceptual design phase to actual engines. The early designs developed by Gussak [1–4], Oppenheim [5, 6], Wolfhard [7], and Murase [8] showed the promise of lean ignition by a hot turbulent jet. Later, Ghoneim and Chen [9], Pitt [10], Yamaguchi [11], Elhsnawi [12], Sadanandan [13], Toulson [14, 15], Gholamisheeri [16], Attard [17], Perera [18], Carpio [19], Shah [20], Karimi [21], Thelen [22], and Biswas [23, 24] further investigated in detail the parametric effects and fundamental physics of turbulent jet ignition in laboratory scale prototype combustors and at engine-relevant conditions. All these studies support that turbulent jet ignition possesses several advantages over traditional spark ignition during ultra-lean combustion such as higher ignition probability, faster burn rates, and multiple ignition kernels.