Plasma jet igniters

There are numerous proposals for the alleviation of these problems, including charge stratification, high levels of turbulence or swirl induced by special valve or piston design, as well as improved electrical ignition systems. These are reviewed by Dale and Oppenheim (1 ). One such form of enhanced ignition system is plasma jet ignition (PJI) and this is the subject of the present review. Because a companion paper in this symposium... 

Figure 1. A cross section of a typical simple plasma Jet igniter. (Reproduced -with permission from Ref. 3. Copyright 19755 Th Combustion Institute.)...

A, plasma jet igniter into air B, plasma Jet ignition of a methane-air mixture with X = 1.3 and C, conventional spark ignition of a methane-air mixture with X = 1.3. Numbers are time in ms. 

Also the gas inside the chamber of the plasma jet igniter is the same as the mixture in the main combustion chamber. This data is compatible with the premise that the plasma jet causes a high degree of turbulence which increases the flame front area and this accounts for the reduction in delay time and increase in burn rate. 

Clearly, as discussed in some detail by Orrin et al (11), fluid mechanical effects are not the whole story when one is using the plasma jet as a source of ignition. Figure 2(B) show a series of photographs of ignition by a plasma jet and for comparison (Figure 2(C)) by a conventional spark in a combustion bomb containing a methane-air mixture at four atmospheres pressure. 

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