Development of Flame Propagation Model considering Lewis Number Effect for Fast Idle Condition

2011 ◽  
Author(s):  
Atsushi Teraji ◽  
Anand Gurupatham
Keyword(s):  
Flame Propagation ◽  
Lewis Number ◽  
Propagation Model

scholarly journals Development of Flame Propagation Model for SI Engine and Its Application to Knoking Prediction

2005 ◽  
Vol 71 (710) ◽  
pp. 2581-2587
Author(s):  
Atsushi TERAJI ◽  
Tsuyoshi TSUDA ◽  
Toru NODA ◽  
Masaaki KUBO ◽  
Teruyuki ITOH
Keyword(s):  
Flame Propagation ◽  
Propagation Model ◽  
Si Engine

Validation of an Ignition and Flame Propagation Model for Multiphase Flows

2011 ◽  
Author(s):  
J. M. Boyde ◽  
P. Le Clercq ◽  
M. Di Domenico ◽  
M. Rachner ◽  
G. C. Gebel ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Flame Propagation ◽  
Multiphase Flows ◽  
Numerical Models ◽  
Turbulent Flame ◽  
Propagation Model ◽  
Test Case ◽  
Turbulent Flame Speed ◽  
Propagation Behavior ◽  
Ignition Characteristics

This paper presents a numerical investigation of a generic lab scale combustor with focus on the ignition characteristics. The test case has been examined thoroughly in a comprehensive measurement campaign to provide a detailed set of boundary conditions and a profound data base of results. The experimental setup comprises five parallel-aligned mono-disperse droplet chains which are ignited, using a focused laser beam. One aspect of the experimental study is the ignitability with respect to the imposed boundary conditions. The second covers the growth and the propagation of the flame after the establishment of an initial kernel. The outcome of the numerical simulations is compared to the experimental results which allows an in-depth assessment of the employed numerical models. The chemistry and, thus, the flame propagation behavior is captured by a turbulent flame speed closure approach with an adaptation to render the model suitable to multiphase flows. For the dispersed phase a Lagrangian particle tracking scheme is employed in combination with a continuous thermodynamics fuel model for the evaporation. The overall good agreement demonstrates the capability of a multiphase flow CFD solver in the field of ignition modeling.

scholarly journals Effects of Lewis Number on the Evolution of Curvature in Spherically Expanding Turbulent Premixed Flames

Fluids ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 12 ◽  
Author(s):  
Ahmad Alqallaf ◽  
Markus Klein ◽  
Nilanjan Chakraborty
Keyword(s):  
Transport Equation ◽  
Burning Rate ◽  
Flame Propagation ◽  
Premixed Flames ◽  
Lewis Number ◽  
Flame Surface ◽  
Turbulent Premixed Flames ◽  
Diffusive Instability ◽  
Negatively Curved ◽  
Positively Curved

The effects of Lewis number on the physical mechanisms pertinent to the curvature evolution have been investigated using three-dimensional Direct Numerical Simulation (DNS) of spherically expanding turbulent premixed flames with characteristic Lewis number of L e = 0.8 , 1.0 and 1.2. It has been found that the overall burning rate and the extent of flame wrinkling increase with decreasing Lewis number L e , and this tendency is particularly prevalent for the sub-unity Lewis number (e.g., L e = 0.8 ) case due to the occurrence of the thermo-diffusive instability. Accordingly, the L e = 0.8 case has been found to exhibit higher probability of finding saddle topologies with large magnitude negative curvatures in comparison to the corresponding L e = 1.0 and 1.2 cases. It has been found that the terms in the curvature transport equation due to normal strain rate gradients and curl of vorticity arising from both fluid flow and flame normal propagation play pivotal roles in the curvature evolution in all cases considered here. The net contribution of the source/sink terms of the curvature transport equation tends to increase the concavity and convexity of the flame surface in the negatively and positively curved locations, respectively for the L e = 0.8 case. This along with the occurrence of high and low temperature (and burning rate) values at the positively and negatively curved zones, respectively acts to augment positive and negative curved wrinkles induced by turbulence in the L e = 0.8 case, which is indicative of thermo-diffusive instability. By contrast, flame propagation effects tend to weakly promote the concavity of the negatively curved cusps, and act to decrease the convexity of the highly positively curved bulges in the L e = 1.0 and 1.2 cases, which are eventually smoothed out due to high and low values of displacement speed S d at negatively and positively curved locations, respectively. Thus, flame propagation tends to smoothen the flame surface in the L e = 1.0 and 1.2 cases.

Sign in / Sign up

Export Citation Format

Share Document