Measurement of transient temperature distribution in a single-cylinder optical engine using laser induced phosphorescence (LIP)

Combustion is the most important process in engine operation; the development of engine technology, therefore, relies upon the advancement of combustion technology. Homogeneous charge compression ignition (HCCI), low temperature combustion (LTC) and controlled auto ignition (CAI) have the potential to allow for better fuel economy and reduced emissions in comparison with spark ignition (SI) combustion. Transient temperature distribution is crucial for understanding combustion, especially heat and mass transfer as well as the chemical reactions of combustion. The authors attempt to measure 2D gas temperature distribution using laser induced phosphorescence (LIP) techniques in a single-cylinder optical engine. The intensity ratio method from phosphorescence was employed to measure the temperature distribution. Dy:YAG phosphor was used, and excited by the 3rd harmonic of an Nd:YAG laser at a wavelength of 355nm. The phosphorescence was captured by an ICCD camera connected to an image doubler. The relationship between the intensity ratios of the two wavelengths and therefore temperature were calculated. The temperature distribution of the compression stroke was measured and compared with the mean temperature calculated from in-cylinder pressure data. The results suggest that this technique can be used for 2D gas-phase temperature measurement. This technique was also used for combustion temperature measurement. The mean temperature from LIP is generally consistent with the mean temperature calculated from in-cylinder pressure in the pre- and post-combustion processes