A Holistic Approach to Pre-Chamber Design, Integration, and Operational Optimization

As internal combustion engines continue to play a critical role in hybrid on-road and numerous non-road applications, there is a continued push to increase efficiency and minimize tailpipe emissions. However, reduced investment in new engine architectures means retrofittable technologies are favored to continue incremental performance improvements to existing engine platforms. To maintain the relatively low capital cost of engine-based powertrains, these technologies must be low-cost and compatible with the diverse mix of fuels that may be encountered across various market segments in the future. Pre-chambers have shown significant potential for improving spark-ignited engine performance across a wide range of engine sizes, from motorsport applications to stationary power, and operating conditions, from stoichiometric operation to ultra-lean. Understanding the degree to which this central combustion technology must be tailored to optimize its performance with a variety of fuels and applications is critical to ensuring that this technology is a possible pathway for developing future fuel-adaptive engine platforms. The study is a combined numerical and experimental investigation of actively fueled pre-chamber operation with both liquid and gaseous fuels. Computational fluid dynamics (CFD) simulations are used to guide initial pre-chamber design. Hardware is then tested on-engine and the CFD model is correlated to experimental results, providing a high-fidelity numerical tool for investigating intra-pre-chamber effects. This study will contrast the pre-chamber operational requirements across different fuels and engine architectures to understand the opportunities and limits of component commonality amongst the various applications and fueling configurations for future engine-based powertrains. Engine bore-related performance parameters, such as end-gas knock, and design considerations, such as cylinder head integration, are captured through the use of both light-duty and heavy-duty engines with similar, scaled pre-chamber hardware. Furthermore, the results provide a roadmap for system performance opportunities associated with pre-chamber-based combustion system optimization.