Naitoh, K., Ayukawa, K., Ikoma, D., Nakai, T. et al., "Fundamental Combustion Experiments of a Piston-Less Single-Point Autoignition Gasoline Engine Based on Compression Due to Colliding of Pulsed Supermulti-Jets," SAE Technical Paper 2016-01-2337, 2016, doi:10.4271/2016-01-2337.
Computational and theoretical analyses for a new type of engine (Fugine), which was proposed by us based on the colliding of pulsed supermulti-jets, indicate a potential for very high thermal efficiencies and also less combustion noise. Three types of prototype engines were developed. One of them has a low-cost gasoline injector installed in the suction port and a double piston system in which eight octagonal supermulti-jets are injected and collide. Combustion experiments conducted on the prototype gasoline engine show high thermal efficiency comparable to that of diesel engines and less combustion noise comparable to that of traditional spark-ignition gasoline engines. This paper presents some combustion experiments of one of the other piston-less prototype engines having bi-octagonal pulsed multi-jets injected from fourteen nozzles. The purpose of this study was to make clear the level of compressive combustion obtained with the pulsed supermulti-jets and air-insulation effect as basic data for application to automobiles, aircraft, and rockets. A torch system for stabilizing the onset of combustion was important in this study because the engine has no pistons and no homogeneous compression at engine start. By developing and employing the torch system, combustion experiments were performed using the colliding of pulsed supermulti-jets. As a result, very strong combustion light was obtained in nine continual cycles, although start of combustion was not still reliable. Therefore, experiments were carried out with a higher oxygen concentration. As a result, more reliable start of combustion with a higher pressure increase and nearly complete air insulation effect were obtained.