Combustion Noise Variability on a DI Diesel Engine

Cylinder pressure excitation is a major source of diesel engine noise. A data acquisition system for obtaining harmonic analysis of cylinder pressure is described. Variability of cylinder pressure harmonic analysis is investigated with respect to cycle-to-cycle, cylinder-to-cylinder, and test-to-test variations. Cycle-to-cycle variation was found to have the largest magnitude. Recommendations for averaging data are included.