Optical Investigation of HCCI Two-Stage Ignition Using Multiple Injection of Synthetic Fuels

Abstract

Different synthetic fuels have been investigated within a variety of optical experiments at a rapid compression machine using diverse optical set-ups. The experiments have been carried out to determine the fuel requirements for good homogenisation and a controlled ignition and heat release for HCCI combustion. A directly actuated piezo injection system, which allows a flexible multiple injection strategy has been used to inject the fuel at different times during the compression stroke. Mie-scatter and Schlieren optics have been applied to investigate the different behaviour of the synthetic fuels concerning evaporation and mixture formation. The auto ignition behaviour of the different fuels has been investigated using an intensified relay optics and combustion chamber probes utilising the two-colour-method and a photo multiplier analysis systems. A multiple injection strategy and a 13 hole injection nozzle for HCCI operation mode with diesel-like fuels have been designed and optimised using CFD simulation prior to the experimental work. The experimental results using synthetic fuels will then be used to verify advanced 3D CFD models for multi component fuels and their behaviour concerning mixture formation and HCCI two-stage ignition.