Combustion regimes and the straining of turbulent premixed flames

Engine hot spots: Modes of auto-ignition and reaction propagation

“…quench. This regime, discussed in Section 6, is identified in [27,28]. It has been shown to be suitable for controlled auto-ignitive engine combustion in [29].…”

Effects of turbulence intensity and length scale on the flame location of premixed turbulent combustion in a diffuser combustor

“…(Borghi 1989, Peters 1989, and Abdel-Gayed et al 1989) depended on velocity and turbulence scale ratios to establish the regimes of premixed turbulent combustion. Therefore, a change in turbulence intensity level and length scale causes a change in the type of combustion zone within the regimes of the premixed turbulent combustion as a result of the change in the physical process.…”

Flame-Turbulence Interactions

“…Formation of a product pocket, however, involves local quenching or "tearing" of the flame front for the pocket to be separated from the contiguous 34 flame front; and two-dimensional images are insufficient to conclude that observed product pockets are truly separate pockets of product gases in three-dimensions [26]. However, experimental evidence using shadowgraph photography exists in support of the formation of product pockets in sufficiently strong turbulence [27]; and in any event, we adopt a two-dimensional definition of product pockets since they contribute to an apparent increase in two-dimensional flame surface areas. Within this definition, the entire perimeter of the flame pockets should be observable within the field of view for the objects to be classified as flame pockets.…”

“…A least-square fit line through the data points show that in order for af/(f> to be zero (u'SL)P2" • 3.3 or u'SL ýZ 10. Therefore, u' must be approxi- Although three-dimensional topology of flame fronts cannot accurately be assessed using a single-sheet two-dimensional methods (Mantzaras et al, 1988) such as used in this study, shadowgraph measurements by Abdel-Gayed et al (1989) demonstrates the possible mecharisms of flame front fragmentation and pocket formations. Therefore, for u' > SL it may be hypothesized that the flame front can no longer be singly-connected resulting in so-called -packet" combustion and within this regime since flame fronts form many separate and locally closed surfaces the flamelet orientation is likely to be isotropic.…”