Abstract
To improve internal combustion engines, it is critical to measure the temperature distribution of their walls. Lifetime-based temperature imaging was performed in this study. The uncertainty was ±2.0℃ for measurements of uniform temperature fields in the range 40-250℃. Single-shot measurements enabled inhomogeneous temperature distributions in the engine with or without flames to be visualized. Even under motoring conditions, there was a large temperature gradient across the side window at the highest position of the piston. The side window temperature decreased near the intake valve. The intake gas flow had a cooling effect and the intake pressure affected the temperature distribution. The engine speed and the coolant temperature increased the temperature but they did not affect the overall temperature distribution. The instantaneous temperature of the top of the piston was visualized in the transient process after firing had commenced. Single-shot imaging was able to identify hot spots, which may generate soot and cause knocking.
