Optical Diagnostics for Gasoline Direct Injection Engines

Abstract

AbstractAdvancements in internal combustion (IC) engine technologies have improved both spark ignition (SI) and compression ignition (CI) engines immensely in terms of fuel efficiency and emissions. Gasoline engines are giving tough competition to their diesel counterparts in the light-duty passenger car segment with continuously increasing market share. Apart from lower exhaust emissions, current generation Gasoline Direct Injection (GDI) engines offer higher power output and superior fuel economy. Nevertheless, automotive researchers and engineers have used many tools to evolve state-of-the-art GDI engine technology continuously. The most important and useful tool in engine development is optical diagnostics. Optical access to the engine allows non-intrusive investigations of the in-cylinder processes using optical/laser-based diagnostics, which provides information not available by any other research tool. This chapter discusses applying such techniques to understand various in-cylinder processes such as spray-flow interactions, fuel–air mixture formation, combustion, and pollutant formation in GDI engines. It includes detailed perspectives that help optimize engine design and control parameters adapted to conventional and alternative fuels. It broadly covers studies related to in-cylinder flow characteristics, sprays characterization, fuel spray-air interactions, fuel evaporation, mixture formation, flame propagation characteristics, and pollutant formation, corresponding to different GDI engine operating parameters. This chapter discusses applications of various optical diagnostic techniques in GDI engine investigations such as particle imaging velocimetry (PIV), Mie-scattering, phase Doppler interferometry (PDI), laser-induced fluorescence (LIF), natural flame chemiluminescence, laser-induced incandescence (LII), OH/CH chemiluminescence. The rich information derived from the optical diagnostic techniques helps develop new-generation GDI engines capable of meeting market requirements and emission compliance.KeywordsGasoline direct injectionOptical diagnosticsIn-cylinder flowsSprayCharge distributionPollutant formation