Toward a Novel Approach for Multimodal Combustion Simulations in Reactivity-Controlled Compression Ignition Engines

Abstract

Reactivity-controlled compression ignition (RCCI) presents a promising avenue for improvements in internal combustion engine efficiency and emissions. As combustion phenomena are critical to optimizing RCCI engine performance independently of flow characteristics, a turbulent combustion model is developed within the PDRs manifold framework. The aim is to contribute to ongoing research on simplified computational models for multimodal combustion and developing a fundamental RCCI combustion model that can be applied across a wide range of fuels. A linked one-dimensional manifold model is proposed to simulate RCCI combustion by decoupling auto-ignition and homogeneous burning. High-reactivity fuel auto-ignition is modeled as an asymptotically non-premixed case, and low-reactivity fuel combustion as an asymptotically premixed case. The ignition delay time (IDT) hypothesis is presented, suggesting that true combustion behavior can be extracted by minimizing characteristic burn times. Preliminary investigations suggest that the IDT hypothesis does not hold for the particular parameters chosen here. However, the analyses conducted in this thesis provide a starting point and some generalized algorithms for future work in simplified multimodal combustion modeling