<div class="section abstract"><div class="htmlview paragraph">We have proposed a new compressive combustion principle leading to the
auto-ignition of fuel by focusing compression due to the collision of the pulsed
supermulti-jets. This principle has the potential of nearly-complete air
insulation due to encasing burned gas around the center of the combustion
chamber and a high compression ratio around the chamber center while suppressing
vibration and noise levels. We have developed the first prototype engine having
a very small combustion chamber of a diameter of 18 mm and also 14 side passages
for the supermulti-jets colliding at the chamber center. Combustion experimental
results indicating air insulation effect and high thrust over 100 N were
obtained as basic data for various types of applications, including automobiles
and aerospace usage such as for rockets. However, it was found that higher
compression due to more jets is necessary to get stabler combustion. Therefore,
by using a metal 3D printer, we have developed the second engine with 24 side
passages of gas jets colliding, while performing direct injection of liquid fuel
at injection pressure over 5 MPa into the combustion chamber. In our previous
report, the experiment without combustion and its computational simulation show
that the second engine enables a higher compression ratio than that of the first
prototype engine. In this research, we conduct fundamental combustion
experiments using the second engine with a direct injection system, purposing to
achieve stable multi-cycle combustion with auto-ignition of the fuel by focusing
compression due to the collision of supermulti-jets. As a result, a stabler
occurrence of combustion is confirmed for the second engine. Experimental data
of wall pressure obtained also indicate that auto-ignition occurs due to
collision of the supermulti-jets while showing a possibility of higher thrust
over 300 N. Furthermore, we qualitatively perform computations of reacting flows
for the second engine, while showing liquid fuel spray atomized strongly by the
gas jets.</div></div>
