Abstract
Prechamber-assisted internal combustion engines allow lean limit extension by replacing the spark plug with multiple, high-temperature, radical-rich jets that entrain and ignite the main chamber charge. This work reports the first investigation of active ultra-lean, active rich, and passive prechamber assisted prechamber engine operation (with a fixed prechamber geometry) through 50 kHz cycle-resolved measurements of formaldehyde planar laser-induced fluorescence (PLIF) and OH* imaging in a heavy-duty optical engine operating at 1200 rpm. The third harmonic of a burst mode laser (355 nm) provided the excitation source for formaldehyde PLIF, and a high-speed CMOS camera collected the fluorescence signal from the side window of the engine. Bottom-view imaging of OH* chemiluminescence was achieved using an intensified high-speed camera. The high-speed image sequence of the prechamber jet formaldehyde layer and OH* captures the main chamber heat release stages and the interaction between the moving piston and the prechamber jet. The prechamber-assisted combustion process in the main chamber could be segmented into three phases: initial jet, jet wall interaction, and Post Jet Combustion. The first two phases differ between active and passive operations owing to the global lambda, while the last phases mostly remain flame propagation driven. Jet wall interaction leading to mixing and vortical transport across the main chamber is pivotal in main chamber heat release rate shaping. The study reports the dynamics and evolution of main chamber combustion in detailed time-resolved setups.
| Original language | English |
|---|---|
| Article number | 112989 |
| Journal | Combustion and Flame |
| Volume | 256 |
| DOIs | |
| State | Published - Oct 2023 |
Funding
The authors express our gratitude to Prof. Mikhail Slipchenko (Spectral Energies, LLC) for the prompt, expert advice on burst mode laser operational challenges and optimization suggestions; Prof. Bengt Johansson (Chalmers) and Dr. Ramgopal Sampath (NTNU) for their early contributions to the prechamber project at KAUST; Dr. Moez Ben Houidi (KAUST) for managing project meetings; Dr. Abdullah S. AlRamadan for proofreading the manuscript. The paper is based upon work supported by Saudi Aramco Research and Development Center FUELCOM3 program under Master Research Agreement Number 6600024505/01. FUELCOM (Fuel Combustion for Advanced Engines) is a collaborative research undertaking between Saudi Aramco and King Abdullah University of Science and Technology (KAUST) to address the fundamental aspects of hydrocarbon fuel combustion in engines and develop fuel/engine design tools suitable for advanced combustion modes. The paper is based upon work supported by Saudi Aramco Research and Development Center FUELCOM3 program under Master Research Agreement Number 6600024505/01 . FUELCOM (Fuel Combustion for Advanced Engines) is a collaborative research undertaking between Saudi Aramco and King Abdullah University of Science and Technology (KAUST) to address the fundamental aspects of hydrocarbon fuel combustion in engines and develop fuel/engine design tools suitable for advanced combustion modes.
Keywords
- Burst-mode laser
- Ignition
- Prechamber assisted combustion (PCC)
- Turbulent jet ignition (TJI)
- Ultra-lean combustion