Spray-wall interaction on n-dodecane spray combustion and soot formation under different wall temperatures

•Impingement spray have lower soot formation compared to free spray.•The greater air entrainment is the main reason for less soot formation from impingement spray.•The influence of wall temperature on soot production is nonlinear.•SWI increases the volume of the vapor-phase spray and the flame volume.•Large amount of soot formation near the wall due to SWI.