Keywords and Phrases
Homogeneous charge compression ignition (HCCI)
"The hypothesis tested in this work is that the surface vibration and radiated sound of an engine operating under HCCI combustion is dominated by the free vibration response of the engine's structural components to an impulsive loading brought about by the rapid energy release of the HCCI combustion process. Recent work by the author has shown that classical vibration theory describing the dynamic response of a single-degree-of-freedom (SDOF) oscillator may capture the major characteristics of the engine surface vibrations. Through an experimental investigation of HCCI combustion engine dynamics this model has been developed further.
A band level analysis of measured engine noise was employed to determine whether low or high frequency oscillations were dominating the acoustic signature of the engine. The results of the band level analysis showed that the combustion behavior associated with the energy release process occurring in the bulk gas dominates the radiated engine noise when compared to the high frequency gas resonant oscillations.
Using an impact hammer technique it was found that the vibration frequencies of oscillation measured on the engine surface do not govern the oscillation frequencies measured during combustion. However it was also found that the oscillation frequencies excited during combustion for all vertical velocity measurement locations were relatively constant regardless of engine firing condition. This result indicates that the frequencies are still governed by constant dynamic properties of the engine however this work has shown they are not local surface vibration modes.
An in-depth analysis of the relation between the cylinder pressure power spectral density (PSD) and measured velocity PSD for various velocity measurement locations was undertaken. It was found the form of the cylinder pressure spectral energy directly modulated the surface velocity spectral energy indicative of a shock loading to the system. It was also found that peak HRR is a good indicator of combustion noise level in an HCCI engine. An analytical model based on the SDOF theory was developed to predict relative levels of HCCI combustion induced vibration metrics. This model provides the crucial link between the engine combustion and dynamic properties necessary for modeling of HCCI engine combustion noise"--Abstract, page iii.
Drallmeier, J. A.
Köylü, Ümit Ö. (Ümit Özgür)
Samaranayake, V. A.,
Wagner, R. M. (Robert M.)
Mechanical and Aerospace Engineering
Ph. D. in Mechanical Engineering
Oak Ridge National Laboratory
National Science Foundation (U.S.)
Missouri University of Science and Technology
xv, 224 pages
© 2011 Jeffery Alexander Massey, All rights reserved.
Dissertation - Restricted Access
Vibration -- Mathematical models
Internal combustion engines -- Combustion -- Testing
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Electronic access to the full-text of this document is restricted to Missouri S&T users. Otherwise, request this publication directly from Missouri S&T Library or contact your local library.http://merlin.lib.umsystem.edu:80/record=b10127776~S5
Massey, Jeffery A., "Development of a simple vibration model for predicting the structural dynamics of an HCCI engine" (2011). Doctoral Dissertations. 20.
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