Auto-ignited kernels during knocking combustion in a spark-ignition engine

Combustion and Exhaust Emission Characteristics of Diesel Micro-Pilot Ignited Dual-Fuel Engine

“…Knocking combustion is a combustion process in which some part or all of the charge may be consumed (autoignited) in the end-gas region at extremely high rates. Much evidence of end-gas mixture auto-ignition followed by knocking combustion can be obtained from highspeed laser shadowgraphs [18], high-speed Schlieren photography [19], chemiluminescent emission [20], and laser-induced fluorescence [21]. In addition, Stiebels et al [22] and Pan and Sheppard [23] showed that multiple autoignition sites occur during knocking combustion.…”

Different combustion modes caused by flame-shock interactions in a confined chamber with a perforated plate

“…Essentially, engine knock and super knock are always accompanied by interactions of flame and shock waves and rapid chemical energy release [10][11][12][13] or a process in which a part of or all of the charge may be consumed at extremely high rates. Thus, it is important to investigate the interactions of flame and shock waves which are the key to revealing the mechanism of knock and super knock for modern SI engines.…”

“…Many experiments have been made in a rapid compression machine (RCM) [33][34][35] as well as in an optical engine withstanding high pressure [11,12] to prove that the autoignition and detonation phenomenon is present in the end region of the chamber when knock and super knock occurs. The resulting speeds of the detonation flame in the range of 1500-2300 m/s are close to Chapman-Jouget (CJ) velocity.…”

Study on Knocking Intensity under In-Cylinder Flow Field in SI Engines Using a Rapid Compression Machine

“…The compression due to flame propagation causes the spontaneous ignition. Numerous studies have been carried out for many decades to explain the mechanism of the knocking occurrence, to identify the factors, and to develop the countermeasures against SI knock [2][3][4][5][6][7][8][9][10][11][12][13][14]. Among them, a lot of studies have been carried out by using Rapid Compression (and Expansion) Machines (RCM, RCEM) and SI engines.…”

“…On the knocking characteristics such as intensity, a few remarkable studies have been carried out [4][5][6][7][8][9][10][11]. Kono et al [5] and Kumagai et al [6] clarified the dependency of the knocking intensity on the volume fraction for flame propagation and they reported that the knocking intensity reaches their maximum at the volume fraction of about 0.6.…”