A Predictive Ignition Delay Correlation Under Steady-State and Transient Operation of a Direct Injection Diesel Engine

A Predictive Ignition Delay Correlation Under Steady-State and Transient Operation of a Direct Injection Diesel Engine

Journal:

ASME Journal of Engineering for Gas Turbines and Power, v.125, No. 2, April 2003

Authors:

D. N. Assanis, Z. S. Filipi, S. B. Fiveland, M. Syrimis

Abstract:

Available correlations for the ignition delay in pulsating, turbulent, two-phase, reacting mixtures found in a diesel engine often have limited predictive ability, especially under transient conditions. This study focuses on the development of an ignition delay correlation, based on engine data, which is suitable for predictions under both steady-state and transient conditions. Ignition delay measurements were taken on a heavy-duty diesel engine across the engine speed/load spectrum, under steady-state and transient operation. The dynamic start of injection was calculated by using a skip-fire technique to determine the dynamic needle lift pressure from a measured injection pressure profile. The dynamic start of combustion was determined from the second derivative of measure cylinder pressure. The inferred ignition delay measurements were correlated using a modified Arrhenius expression to account for variations in fuel/air composition during transirents. The correlation has been compared against a number of available correlations under staeady-state conditions. In addition, comparisons between measurements and predictions under transient conditions are made using the extended thermodynamics simulation frame-work of Assanis and Heywood. It is concluded that the proposed correlation provides better predictive capability under both steady-state and transient operation.

Paper: P2003_07.PDF