We have proposed the engine featuring a new compressive combustion principle based on pulsed supermulti-jets colliding through a focusing process in which the jets are injected from the chamber walls to the chamber center. This principle has the potential for achieving relatively silent high compression around the chamber center because autoignition occurs far from the chamber walls and also for stabilizing ignition due to this plug-less approach without heat loss on mechanical plugs including compulsory plasma ignition systems. Then, burned high temperature gas is encased by nearly complete air insulation, because the compressive flow shrinking in focusing process gets over expansion flow generated by combustion. If the compression level based on the supermulti-jets with pistons and cascades added is optimized for a certain size of the present autoignition region between that of very narrow spark ignition and homogeneous-charge compression ignition (HCCI) at very lean burning conditions, this principle for attaining higher thermal efficiency and higher power is applicable to automobiles, aircraft, rockets, and also to flying cars to be developed in the future. High compression only around the chamber center will not bring knocking. It may also enable the downsizing or elimination of a cooling system, resulting in lower prices. Then, the size of autoignition region between that of very narrow spark ignition and homogeneous-charge compression ignition (HCCI) also has combustion stability increased at very lean burning and possibility of low emissions including NOx and soot, while learning the strategy from low NOx and higher thermal efficiency achieved for hydrogen engine reported by Takagi et al. This paper presents four new items of evidence based on experimental data and computational considerations. The first evidence concerns combustion experiments in a piston-less engine having 14 pulsed jets colliding through a focusing process. This is the first prototype engine for confirming this compressive combustion principle, which over the last three years has reliably shown noise-less, high thrust data under lean fuel conditions and a low wall temperature. We confirmed that combustion (detonation) occurs around the chamber center. The second evidence concerns experiments conducted with a strongly asymmetric, double piston engine having a little high temperature domain around the chamber center due to weak compression of eight pulsed jets colliding through a focusing process. This second prototype engine intended for automobiles includes piston compression and pressure gain due to pressure wave reflection from the chamber wall, which provides the possibility for high thermal efficiency related to the nearly complete air insulation effect. It is also stressed that this engine includes a new type of variable motions of the intake-exhaust valve systems. The third evidence concerns quantitative clarification of the compression level under a condition without combustion. The fourth evidence concerns the fuel atomization effect due to the high-speed jets, which can reduce the fuel tank pressure.
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