scholarly journals Direct numerical simulation of a spatially developing n-dodecane jet flame under Spray A thermochemical conditions: Flame structure and stabilisation mechanism

2020 ◽  
Vol 217 ◽  
pp. 57-76 ◽  
Author(s):  
Deepak K. Dalakoti ◽  
Bruno Savard ◽  
Evatt R. Hawkes ◽  
Armin Wehrfritz ◽  
Haiou Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Flame Structure ◽  
Jet Flame

Three-dimensional direct numerical simulation of a turbulent lifted hydrogen jet flame in heated coflow: a chemical explosive mode analysis

2010 ◽  
Vol 652 ◽  
pp. 45-64 ◽  
Author(s):  
T. F. LU ◽  
C. S. YOO ◽  
J. H. CHEN ◽  
C. K. LAW
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Near Field ◽  
Three Dimensional ◽  
Mode Analysis ◽  
Scalar Dissipation ◽  
Complex Flows ◽  
Jet Flame ◽  
Auto Ignition ◽  
Grid Points

A chemical explosive mode analysis (CEMA) was developed as a new diagnostic to identify flame and ignition structure in complex flows. CEMA was then used to analyse the near-field structure of the stabilization region of a turbulent lifted hydrogen–air slot jet flame in a heated air coflow computed with three-dimensional direct numerical simulation. The simulation was performed with a detailed hydrogen–air mechanism and mixture-averaged transport properties at a jet Reynolds number of 11000 with over 900 million grid points. Explosive chemical modes and their characteristic time scales, as well as the species involved, were identified from the Jacobian matrix of the chemical source terms for species and temperature. An explosion index was defined for explosive modes, indicating the contribution of species and temperature in the explosion process. Radical and thermal runaway can consequently be distinguished. CEMA of the lifted flame shows the existence of two premixed flame fronts, which are difficult to detect with conventional methods. The upstream fork preceding the two flame fronts thereby identifies the stabilization point. A Damköhler number was defined based on the time scale of the chemical explosive mode and the local instantaneous scalar dissipation rate to highlight the role of auto-ignition in affecting the stabilization points in the lifted jet flame.

scholarly journals Edge flame structure in a turbulent lifted flame: A direct numerical simulation study

2016 ◽  
Vol 169 ◽  
pp. 110-128 ◽  
Author(s):  
Shahram Karami ◽  
Evatt R. Hawkes ◽  
Mohsen Talei ◽  
Jacqueline H. Chen
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Simulation Study ◽  
Flame Structure ◽  
Lifted Flame

Direct Numerical Simulation of a Non-Premixed Impinging Jet Flame

2006 ◽  
Vol 129 (8) ◽  
pp. 951-957 ◽  
Author(s):  
Xi Jiang ◽  
Hua Zhao ◽  
Kai H. Luo
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Impinging Jet ◽  
Jet Flame ◽  
Law Of The Wall ◽  
Wall Distance ◽  
Variable Density Flow ◽  
Nonisothermal Flows ◽  
The Law ◽  
Impinging Flame

A non-premixed impinging jet flame at a Reynolds number 2000 and a nozzle-to-plate distance of two jet diameters was investigated using direct numerical simulation (DNS). Fully three-dimensional simulations were performed employing high-order numerical methods and high-fidelity boundary conditions to solve governing equations for variable-density flow and finite-rate Arrhenius chemistry. Both the instantaneous and time-averaged flow and heat transfer characteristics of the impinging flame were examined. Detailed analysis of the near-wall layer was conducted. Because of the relaminarization effect of the wall, the wall boundary layer of the impinging jet is very thin, that is, in the regime of viscous sublayer. It was found that the law-of-the-wall relations for nonisothermal flows in the literature need to be revisited. A reduced wall distance incorporating the fluid dynamic viscosity was proposed to be used in the law-of-the-wall relations for nonisothermal flows, which showed improved prediction over the law of the wall with the reduced wall distance defined in terms of fluid kinematic viscosity in the literature. Effects of external perturbation on the dynamic behavior of the impinging flame were found to be insignificant.

Numerical Simulation of Effects of Gravity on the Micro Jet Flame in the Confined Space

2013 ◽  
Vol 732-733 ◽  
pp. 127-132
Author(s):  
Yun Hua Gan ◽  
Yan Lai Luo
Keyword(s):  
Numerical Simulation ◽  
Flame Structure ◽  
Numerical Data ◽  
Glass Tube ◽  
Flame Length ◽  
Zero Gravity ◽  
Gravity Level ◽  
Confined Space ◽  
Jet Flame ◽  
Ceramic Tube

A microscale ceramic tube was used as a burner jet, and a coaxial jet flame was established in the confined space between the ceramic tube and the outer quartz glass tube. The effects of gravity on the small jet flame characteristics in the confined space were investigated numerically. Comparisons between the experimental data and the numerical data showed that characteristics of the small jet flame structure and temperature field were in good agreement. It verified the accuracy of the numerical simulation. Numerical simulations of flame characteristics at zero gravity level were performed. The results show that the gravity level has a greater influence on the flame width than that on the flame length. The chemical reaction rate is larger under the condition of normal gravity than that of zero gravity.

J0110102 Direct Numerical Simulation of a Pulverized Coal Jet Flame : effect of equivalence ratio

2015 ◽  
Vol 2015 (0) ◽  
pp. _J0110102--_J0110102-
Author(s):  
Masaya MUTO ◽  
Takumi HARA ◽  
Kenji TANNO ◽  
Ryoichi KUROSE ◽  
Satoru KOMORI
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Equivalence Ratio ◽  
Pulverized Coal ◽  
Jet Flame
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