An analytical method for reducing combustion instability in homogeneous charge compression ignition engines through cycle-to-cycle control

Abstract

Late-phasing homogeneous charge compression ignition operating conditions have the potential to expand the useful operating range of homogeneous charge compression ignition in internal combustion engines. However, significant combustion instabilities can occur at late-phasing operating conditions. Combustion phasing and work output variations at these conditions are characterized by a pattern in which the combustion phasing alternates between being earlier than the desired timing and later than the desired timing. This characteristic can be traced to a negative eigenvalue in a simplified, discrete-time analytical model of homogeneous charge compression ignition dynamics. The model forms the basis for the design of a simple controller that is shown to reduce combustion timing variations in simulation. Experimental results illustrate the controller successfully reduces the cyclic variations in combustion by altering the exhaust valve timing, resulting in stable combustion and an expanded operating range.

Cyclic dispersion in engine combustion—Introduction by the special issue editors

“…14 The articles by Larimore et al 15 and Jungkunz et al 16 focus primarily on the simulation and control of deterministic processes which have been shown to dominate cyclic dispersion for advanced combustion modes which operate near the edge of stability, 9 whereas the article by Spelina et al 14 addresses aspects of knock from a purely stochastic perspective.…”

“…[14][15][16] Of course, these categories, while convenient, are neither unique nor orthogonal. For the reader's convenience, we also note the mapping of the articles to engine types:…”

“…Three articles in this special issue explore statistical and physics-based models for improved control to reduce cyclic dispersion, thereby enabling more robust LTC 15,16 as well as improved knock prediction in more conventional modern SI engines.…”

“…Conventional spark-ignition (SI) 6,[9][10][11]14 and compression-ignition (CI) (diesel) engines; 7,12 Spray-guided stratified-charge engines; 4,5 Low-temperature combustion (LTC) engines, 8,9,12,13,15,16 including homogeneous charge compression ignition (HCCI) 8,9,15,16 and reactivitycontrolled compression ignition (RCCI). 12,13 In this introductory overview, we place these articles (which include three invited review papers 4,9,10 ) in the larger context of engine research and offer brief but (we hope) tantalizing summaries.…”

“…19,20 Cylinder-pressure measurement is also increasingly being used for engine control, as illustrated for HCCI in this special issue. 15,16 High-speed imagingmodernized with large-memory digital cameras that can record thousands of consecutive engine cycles at frame rates of 10-100 kHz and beyond-has been extended beyond combustion luminosity to quantitative measurement of flow fields by particle-image velocimetry (PIV) and chemical species (e.g. fuel and OH) by laser-induced fluorescence (LIF).…”