Research

SNU Automotive Laboratory

Research topic

Hydrogen Combustion at Lean Conditions

Global warming is becoming more serious and the regulations on carbon-dioxide emissions are being tightened around the world. Spark-ignited engines, which mainly use gasoline fuel, are improving the thermal efficiency to reduce carbon-dioxide emissions, however they are taking steps with new combustion concepts and other fuels. Lean combustion strategy is expected to be more efficient by driving the engines outside the stoichiometric conditions through overcharging. However, since lean combustion has the disadvantage of combustion instability, studies on the flammability around spark plugs have been actively conducted to compensate for this. Hydrogen is a fuel suitable for stable combustion because of its excellent flammability, and doesn’t emit carbon-dioxide as a product after combustion. In SNUAL, hydrogen combustion experiments are being conducted using a single-cylinder engine, which is convenient to change the engine hardware. Several studies are tested for the purpose of analyzing the in-cylinder flow and ignition energy that affects the stability of hydrogen-lean combustion. In addition, the influence of changes in engine parameters such as fuel injection method, compression ratio and valve timing is analyzed to improve the thermal efficiency.

  • Schematic diagram of single cylinder hydrogen combustion engine

LES Simulation of SI Engines

LES simulation has the strength to identify the cause of CCV in the engine. LES simulation is a technique that can simulate CCV by spatially simulating flow analysis, but it is a research field that has recently begun to emerge because it requires a lot of time and large computing power. SNUAL studied the method of analyzing the resolved turbulence and suggested the direction of the LES simulation and studied the effect of the resolved turbulence on the combustion of the engine to reduce CCV. Based on the contents of research, SNUAL intend to provide a theoretical basis for a method to reduce the CCV of the GDI HEV engine under lean burn condition, which is a next-generation engine.

  • Simulating resolved flame surface in LES simulation
  • Simulated flow field by RANS and LES

Dual-Fuel Modeling

Dual-Fuel combustion is one of the advanced combustion concepts to improve high thermal efficiency while maintaining low emissions. SNUAL studied dual-fuel combustion with various fuels such as propane, gasoline, and CNG by experiments, and developed a dual-fuel combustion model of CFD simulation. CFD enables to study of the combustion phenomena in detail since it is possible to visualize what experiments can not measure. Through dual-fuel combustion simulation, it is expected to understand the complex combustion mode in dual-fuel combustion and be used in further optimization of dual-fuel engines.

  • Pressure & HRR of experiment and simulation
  • Average-, maximum-temperature and species (OH, CH2O)