turbulent flames
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2022 ◽  
Vol 34 (1) ◽  
pp. 015114
Author(s):  
Jessica Chambers ◽  
Hardeo M. Chin ◽  
Alexei Y. Poludnenko ◽  
Vadim N. Gamezo ◽  
Kareem A. Ahmed

Fuel ◽  
2021 ◽  
Vol 306 ◽  
pp. 121678
Author(s):  
Yuzuru Nada ◽  
Yoshiyuki Kidoguchi ◽  
Hidenari Sakai ◽  
Yuto Moriyama

Author(s):  
Rishikesh Ranade ◽  
Tarek Echekki ◽  
Assaad R. Masri
Keyword(s):  

2021 ◽  
Vol 23 (3) ◽  
pp. 169
Author(s):  
C. Yu ◽  
U. Maas

In order to address the impact of the concentration gradients on the chemistry – turbulence interaction in turbulent flames, the REDIM reduced chemistry is constructed incorporating the scalar dissipation rate, which is a key quantity describing the turbulent mixing process. This is achieved by providing a variable gradient estimate in the REDIM evolution equation. In such case, the REDIM reduced chemistry is tabulated as a function of the reduced coordinates and the scalar dissipation rate as an additional progress variable. The constructed REDIM is based on a detailed transport model including the differential diffusion, and is validated for a piloted non-premixed turbulent jet flames (Sandia Flame D and E). The results show that the newly generated REDIM can reproduce the thermo-kinetic quantities very well, and the differential molecular diffusion effect can also be well captured.


2021 ◽  
Vol 928 ◽  
Author(s):  
H.C. Lee ◽  
P. Dai ◽  
M. Wan ◽  
A.N. Lipatnikov

Apparent inconsistency between (i) experimental and direct numerical simulation (DNS) data that show the significant influence of differential diffusion on the turbulent burning rate and (ii) recent complex-chemistry DNS data that indicate mitigation of the influence of differential diffusion on conditioned profiles of various local flame characteristics at high Karlovitz numbers, is explored by analysing new DNS data obtained from lean hydrogen–air turbulent flames. Both aforementioned effects are observed by analysing the same DNS data provided that the conditioned profiles are sampled from the entire computational domain. On the contrary, the conditioned profiles sampled at the leading edge of the mean flame brush do not indicate the mitigation, but are significantly affected by differential diffusion phenomena, e.g. because reaction zones are highly curved at the leading edge. This observation is consistent with a significant increase in the computed turbulent burning velocity with decreasing Lewis number, with all the results considered jointly being consonant with the leading point concept of premixed turbulent combustion. The concept is further supported by comparing DNS data obtained by allowing for preferential diffusion solely for a single species, either atomic or molecular hydrogen.


Author(s):  
Xiang Qian ◽  
Hao Lu ◽  
Chun Zou ◽  
Hong Yao

The understanding of energy transfer in fluids is important for the accurate modeling of turbulent reacting flows. In this study, we investigate interscale kinetic energy transfer and subgrid-scale (SGS) backscatter using data from direct numerical simulations (DNSs) of premixed isotropic turbulent flames. Results reveal that in the examined premixed flames, the pressure transfer term appearing in the transport equation of turbulent kinetic energy dominates the nonlinear advection and the dissipation at large scales, and noticeably contributes to the inverse kinetic energy cascade. Filtered DNS data show that SGS backscatter is correlated with the appearance of positive pressure-dilatation work, i.e. thermal expansion. A priori test results of three SGS stress models reveal that the Smagorinsky stress model is unable to capture SGS backscatter, but that two nonlinear structural stress models are able to predict SGS backscatter.


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