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In this paper an alternative method for collecting laser induced fluorescence (LIF) signals from engines with limited optical access is presented. An endoscopic detection system has been used for LIF visualisation of both gaseous and liquid fluids in a DISI-engine. The use of an endoscope made it possible to monitor parts of the combustion chamber that could not be accessed through the piston with conventional optics. Brief investigations of the signal collection efficiency have been performed on the endoscopic system as well as on a system based upon conventional optics. The technique shows promising results and the use of endoscopic detection systems should be considered as a complement to using advance design quarts piston crowns for conventional detection through the piston.

This paper presents an investigation of a Volvo Direct Injection Spark Ignition (DISI) engine, where the fuel distribution and the in-cylinder flow field have been mapped by the use of laser techniques in an engine with optical access. Along with the experimental work, CFD-modelling of flow and fuel distribution has been performed. Laser Induced Fluorescence (LIF) visualisation of the fuel distribution in a DI-engine has been performed using an endoscopic detection system. Due to the complex piston crown geometry it was not possible to monitor the critical area around the sparkplug with conventional, through the piston, detection. Therefore, an endoscope inserted in the spark plug hole was used. This approach gave an unrestricted view over the desired area. In addition, the in-cylinder flow fields have been monitored by Particle Image Velocimetry (PIV) through cylinder and piston. The results from both the LIF and the PIV measurements have been compared with CFD-modelling at Volvo.