Experimental Analysis of Piston Surface Temperature in a Heavy Duty Compression Ignition Engine

The heat transfer processes occurring in a compression ignition engine are complex, especially considering flame-wall interaction on the piston crown from impinging jets. To study the heat flux occurring on the piston in a heavy-duty diesel engine, a piston was instrumented with fifteen thermocouples and a wireless telemetry system. Eight of the thermocouples are high speed surface thermocouples placed primarily in regions with significant flame-wall interaction, providing crank-resolved surface temperature data. This work presents the first experimental datasets collected with this instrumented piston, describing in detail the thermocouple location selection process as well as data processing and uncertainty quantification for the high-speed surface thermocouples with a particular emphasis on cyclic variability and sensor-to-sensor variability. With this methodology established, data from this piston can be used for modeling and simulation studies as well as for studying the impact of operating conditions on heat flux and flame-wall interaction. The analysis showed that there were significant differences in observed cyclic variability of transient heat flux among the different surface thermocouples that did not appear physical. The sensors did appear able to capture phenomenological aspects of the heat flux process of mixing controlled combustion though the magnitude of transient heat flux appeared higher than expected and further work, including repeatability tests with additional instrumented pistons, is required to form stronger conclusions.