Naitoh, K., Ikoma, D., Sagara, H., Tamura, T. et al., "Two Small Prototype Engines Developed based on Pulsed Supermulti-Jets Colliding: Having a Potential of Thermal Efficiency Over 60% with Satisfactory Strength of Structure," SAE Technical Paper 2014-32-0099, 2014, https://doi.org/10.4271/2014-32-0099.
In our previous reports based on computations and fluid dynamic theory, we proposed a new compressive combustion principle for an inexpensive and relatively quiet engine reactor that has the potential to achieve thermal efficiency over 50% even for small combustion chambers having less than 100 cc. This can be achieved with colliding supermulti-jets that create complete air insulation to encase burned gas around the chamber center. We originally developed two small prototype engine systems for gasoline. First one with one rotary valve for pulsating intake flow and sixteen nozzles of jets colliding has no pistons. Next, we developed the second one having a strongly-asymmetric double piston system with the supermulti-jets colliding, although there are no poppet valves. The second prototype engine can vary point-compression strength due to the supermulti-jets and homogeneous compression level due to piston, by changing phase and size of two gears. A motoring test done for evaluating the strength of structure shows that this engine stably works over 4000rpm. Experimental data of combustion with a starter motor indicates a possibility of stable engine start for gasoline without any plugs and thermal efficiency of the order of traditional piston engines or a little more.