A predictive Livengood–Wu correlation for two-stage ignition

Abstract

The Livengood–Wu correlation has been widely used to predict the state of auto-ignition in internal combustion engines, although its application to two-stage ignition processes remains unresolved. In this study, the original Livengood–Wu integral is extended to such two-stage ignition process and applied to simulations of typical operations within homogeneous charge compression ignition engines. Specifically, based on recent understanding of the global and detailed kinetics of low-temperature chemistry leading to ignition, simplified Arrhenius-based global reaction expressions were developed for both stages of constant-state auto-ignition. It is shown that the original Livengood–Wu integral works well for the first-stage ignition delay, as demonstrated in previous studies. Furthermore, by also accurately describing the cool flame temperature and pressure increment at the end of the first-stage ignition, the second-stage ignition delay can in addition be coupled with the first-stage ignition and predicted satisfactorily with a second integral. This formulation is then applied to extensive homogeneous charge compression ignition engine operation conditions, showing satisfactory predictive capability.

On the Interpretation and Correlation of High‐Temperature Ignition Delays in Reactors with Varying Thermodynamic Conditions

“…While the base L‐W method is inappropriate for describing these effects, it is worth noting that, to address the NTC‐affected ignition, low‐temperature chemistry can be further included. Cool flame reactivity and two‐stage ignition under advanced compression ignition conditions can be accurately predicted using a staged L‐W integral method . Empirical correlation of IDT under constant volume has been obtained based on conventional L‐W including NTC, which is further adopted in a recent work to correlate the IDT of fuel blends based on individual components and mixture composition.…”

Target-Oriented Fuel Design for the Homogeneous Charge Autoignition Combustion Mode: A Case Study of a n-Heptane–PODE3–Ethanol Mixture. 2. Identification of a Functional Configuration of Fuel Components

“…It is necessary to use less complex surrogate fuel to emulate the physical properties, chemical properties, and especially the chemical kinetics . Second, the quantitative structure property relationship (QSPR) method establishes a model to link the fuel molecular structure and physical/chemical properties like boiling point, viscosity, density, research octane number (RON), and cetane number (CN). , Third and fourth, the Livengood–Wu correlation and its extended form , are applied to predict the ignition delay time in the single-stage ignition process and dual-stage ignition process. Fifth and sixth, the octane sensitivity , and octane index , are the important fuel properties to describe the fuel autoignition quality in SI engine and HCCI engine.…”

Sensitivity analysis and validation of a predictive procedure for high and low-temperature ignition delays under engine conditions for n -dodecane using a Rapid Compression-Expansion Machine

“…However, this methodology leads to very long computing times. Besides, Edenhofer et al Moreover, Pan et al [26] modified the original Livengood & Wu correlation to extend its validity to fuels that show a two stage ignition pattern.…”