Fluid Flow in the Squish-Jet Combustion Chamber

Abstract

Fluid flow characteristics near top dead centre (TDC) were measured in three different combustion chambers designed to generate squish flow and to enhance turbulence generation in internal combustion engines. One of the combustion chambers was a plain bowl-in-piston type, whereas the remaining two were different configurations of the squishjet chamber, which has a unique geometry for forming jets that converge radially inwards as TDC is approached. Both particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) were used to measure mean velocities and turbulent fluctuations near to TDC. To accurately and consistently set the initial and boundary conditions, the University of British Columbia Rapid Intake and Compression Machine (UBC-RICM) was used. The microscopic particles used for PIV and LDV seeding were introduced into the cylinder by a novel system developed to suit the momentary flow in the UBC-RICM. The experimental study led to a greater understanding of the flow processes inside these complex combustion chambers. The results also indicated that squish-jet chambers tend to generate higher levels of turbulence than plain bowl-in-piston chambers do, even though they may generate lower mean squish velocities. These results will also be used in a future study to assess the validity of squish flow predictions made by the computational fluid dynamic code, KIVA-3V.