Transient heat flux measurements were obtained at four positions on the cylinder head of a four-stroke single-cylinder spark-ignition engine. Tests were performed for both fired and motored operation of the engine. The primary engine operational variable was engine speed. The results showed that the heat flux varies considerably with position of measurement. At fired conditions, the initial high rate of increase of heat flux at each position of measurement correlated with the calculated time of arrival of the flame at that position. Finally, as expected, the peak heat flux was found to increase with increased engine speed.
Surface temperature measurements were performed in a large bore two-stroke diesel engine used for ship propulsion. A specially designed fast-response surface thermocouple was used together with an embedded standard K-type thermocouple to measure surface temperature and heat flux with high temporal resolution.
Heat flux calculations were carried out both analytically and numerically showing good agreement between the results. Measurements were carried out at three different engine load conditions (25%, 30% and 50% load) in one of the fuel atomizers in the cylinder head. Cyclic surface temperature variations of up to approximately 80 K with a peak temperature of 860 K were observed.
The magnitude of the perturbation of the temperature field due to the presence of the thermocouples was investigated by three dimensional CFD simulations.
Stagnation Point Heat Flux Measurements in a Plasma Wind Tunnel Using a Diamond Heat Transfer Gauge
