Naitoh, K., Kojima, K., Okamoto, T., Yamagishi, K. et al., "Physical Theory of the Single-Point Auto-Ignition Engine Based on Supermulti-Jets Colliding with Pulse: Leading to Thermal Efficiency over 60% at Various Engine Speeds and Loads of Automobiles," SAE Technical Paper 2014-01-2640, 2014, https://doi.org/10.4271/2014-01-2640.
This paper proposes a new compressive combustion principle for an inexpensive, lightweight, and relatively quiet engine reactor that has the potential to achieve incredible thermal efficiency over 60% even for small engines having strokes shorter than 100mm, whereas eco-friendly gasoline engines for today's automobiles use less than 35% of the supplied energy for work on average. This level of efficiency can be achieved with colliding supermulti-jets that create air insulation to encase burned gas around the chamber center, thereby avoiding contact with the chamber walls, including the piston. Emphasis is also placed on the fact that higher compression results in less combustion noise because of the encasing effect. We will first show that numerical computations done for two jets colliding in line quantitatively agree with shock-tube experiment and theoretical value based on compressible fluid mechanics. Next, computations for colliding of many pulse jets distributed with point-symmetry show a high compression ratio over 30:1, pressure ratio over 100:1, and compression temperature over 1200K. A new P-V diagram extended for this engine concept is also shown, which is between the Otto and Lenoir cycles.