Investigation of the Sources of Combustion Noise in HCCI Engines

• Published in: SAE International journal of engines Vol. 7; no. 2; pp. 730 - 761
• Main Authors: Dernotte, Jeremie, Dec, John, Ji, Chunsheng
• Format: Journal Article
• Language: English
• Published: Warrendale SAE International 2014; SAE International, a Pennsylvania Not-for Profit
• Subjects: Acoustic noise; Acoustic resonance; Combustion; Cylinders; Datasets; Engine noise; Engines; Frequency ranges; Knock; Noise; Noise levels; Noise measurement; Parameter sensitivity; Resonance; Sound intensity
• ISSN: 1946-3936; 1946-3944; 1946-3944
• DOI: 10.4271/2014-01-1272

This article presents an investigation of the sources combustion-generated noise and its measurement in HCCI engines. Two cylinder-pressure derived parameters, the Combustion Noise Level (CNL) and the Ringing Intensity (RI), that are commonly used to establish limits of acceptable operation are compared along with spectral analyses of the pressure traces. This study focuses on explaining the differences between these two parameters and on investigating the sensitivity of theCNLto the ringing/knock phenomenon, to which the human ear is quite sensitive. Then, the effects of independently varying engine operating conditions such as fueling rate, boost pressure, and speed on both theCNLandRIare studied.
Results show that theCNLis not significantly affected by the high-frequency components related to the ringing/knock phenomenon. In contrast,CNLis found to be sensitive to increasing energy in the 0.4 to 2.0 kHz frequency range generated by the combustion-induced uniform pressure rise. Parametric investigations emphasize the fact that theRIand theCNLare designed to provide two distinctly different but complementary measurements.RIis designed to correlate with the sound produced by the resonating wave leading to knock. Hence, anRIlimit appears to be a better criterion for avoiding knocking combustion and its detrimental effects (irritating noise, loss of thermal efficiency, engine damage). However,RIis not appropriate for estimating the overall noise of the combustion event since it does not consider the noise generated by the combustion-induced uniform pressure rise. In contrast, theCNLprovides a valuable metric for the overall loudness of the combustion event. However, theCNLis not sensitive to knock-induced noise, so the irritating noise of knock is not accounted for in theCNL, and theCNLis not appropriate for estimating the onset of knock.