On the use of planar laser-induced phosphorescence (PLIP) for combustion temperature measurement in SI engines

Abstract

Combustion is the most important process in courses of engine running, the development of engine technology, therefore, relies upon the advancement of combustion technology. Homogeneous charge compression ignition (HCCI) or controlled auto ignition (CAI) have potential to get lean burn, economy and good emission than spark ignition (SI) combustion. In order to investigate the effects of mixture charging to combustion, the formative process of mixture should be controlled to form stratified or homogeneous charge, second a new technique was put forward and used for studying stratified and homogeneous combustion. Transient temperature distribution is crucial for combustion study, especially for heat and mass transfer, physical and chemical action of overflow combustion. It is very difficult to get the transient temperature distribution. In this thesis the author try to measure the 2D gas temperature distribution using laser induced phosphorescence technique at a small optical engine. According to the excited property, intensity ratio method was used. The calibration was conducted by measuring the surface temperature of solid objects in a test cell. The Dy:YAG phosphor powder was excited by 355nm wavelength of a Nd:YAG laser. The median particle diameter was 4um. The phosphorescence was captured an ICCD camera connected with an image doubler. The relationship between the intensity ratios of two wavelengths with temperature was calculated. The temperature distribution of compression stroke was measured and compared with mean temperature calculated from pressure data, the maximum error is 8.35%, this suggest that this technique can be used for 2D gas phase temperature measurement. And this technique was used for 2D combustion temperature measurement in this optical engine. The flame propagation was studied by temperature distribution, three phases of combustion marked from temperature distribution is consistent with the result gotten from fuel burned mass fraction. The mean temperature of LIP have a good consistency with the mean temperature calculated from pressure at pre combustion and after combustion, but the error is more than 10% at main combustion because of chemiluminescence of combustion.</p