Optical Diagnostic Study on Improving Performance and Emission in Heavy-Duty Diesel Engines Using a Wave-Shaped Piston Bowl Geometry and Post Injection Strategies

This study explores the potential benefits of combining a wave-shaped piston geometry with post injection strategy in diesel engines. The wave piston design features evenly spaced protrusions around the piston bowl, which improve fuel-air mixing and combustion efficiency. The 'waves' direct the flames towards the bowl center, recirculating them and utilizing the momentum in the flame jets for more complete combustion. Post injection strategy, which involves a short injection after the main injection, is commonly used to reduce emissions and improve fuel efficiency. By combining post injections with the wave piston design, additional fuel injection can increase the momentum utilized by the flame jets, potentially further improving combustion efficiency. To understand the effects and potential of the wave piston design with post injection strategy, a single-cylinder heavy-duty compression-ignition optical engine with a quartz piston is used. The piston bowl is modified to remove waves on one side, allowing for a direct comparison between the wave and non-wave piston designs under identical engine operating conditions. Natural Luminosity is used as an optical diagnostic technique to visualize flame-piston and flame-flame interactions. The engine is operated under mid-load conditions (~9 bar IMEP) with different post injection strategies. The study provides insights into the potential benefits of combining the wave piston design with post injection strategy for improving combustion efficiency and engine performance in heavy-duty diesel engines.