Analysis of the relationship between near-wall velocity distribution and wall heat flux under diesel spray flame impingement in an RCEM

To clarify the relationship between the near-wall flow and the heat flux through the wall, the velocity distribution of the diesel spray flame and the heat flux at the combustion chamber wall were measured in a rapid compression and expansion machine (RCEM), which has a twodimensional combustion chamber. The velocity distribution of the diesel spray flame near the wall was measured by the particle image velocimetry (PIV), and the heat flux through the wall where the diesel spray flame impinges was measured using a newly developed multi-point heat flux sensor. Furthermore, the velocity gradient tensor was calculated based on the measured velocity distribution results, and the effect of the shear flow characteristics on wall heat transfer was analyzed. As a result, the higher the injection pressure leads the higher the peak value of the heat flux. A fluctuation of the heat flux exhibits the same trend as the fluctuations of the velocity, and a high heat flux appeared in the high-velocity gradient tensor region, which suggests that the characteristics of shear flow near the wall can affect the heat flux.