Entropy 2013, 15(5), 1540-1566; doi:10.3390/e15051540
Article

A Direct Numerical Simulation-Based Analysis of Entropy Generation in Turbulent Premixed Flames

School of Mechanical and Systems Engineering, Newcastle University, Claremont Road, NE1 7RU Newcastle-Upon-Tyne, UK
* Author to whom correspondence should be addressed.
Received: 8 January 2013; in revised form: 12 April 2013 / Accepted: 23 April 2013 / Published: 29 April 2013
PDF Full-text Download PDF Full-Text [1139 KB, Updated Version, uploaded 3 May 2013 15:34 CEST]
The original version is still available [1238 KB, uploaded 29 April 2013 16:26 CEST]
Abstract: A compressible single step chemistry Direct Numerical Simulation (DNS) database of freely propagating premixed flames has been used to analyze different entropy generation mechanisms. The entropy generation due to viscous dissipation within the flames remains negligible in comparison to the other mechanisms of entropy generation. It has been found that the entropy generation increases significantly due to turbulence and the relative magnitudes of the augmentation of entropy generation and burning rates under turbulent conditions ultimately determine the value of turbulent second law efficiency in comparison to the corresponding laminar values. It has been found that the entropy generation mechanisms due to chemical reaction, thermal conduction and mass diffusion in turbulent flames strengthen with decreasing global Lewis number in comparison to the corresponding values in laminar flames. The ratio of second law efficiency under turbulent conditions to its corresponding laminar value has been found to decrease with increasing global Lewis number. An increase in heat release parameter significantly augments the entropy generation due to thermal conduction, whereas other mechanisms of entropy generation are marginally affected. However, the effects of augmented entropy generation due to thermal conduction at high values of heat release parameter are eclipsed by the increased change in availability due to chemical reaction, which leads to an increase in the second law efficiency with increasing heat release parameter for identical flow conditions. The combustion regime does not have any major influence on the augmentation of entropy generation due to chemical reaction, thermal conduction and mass diffusion in turbulent flames in comparison to corresponding laminar flames, whereas the extent of augmentation of entropy generation due to viscous dissipation in turbulent conditions in comparison to corresponding laminar flames, is more significant in the thin reaction zones regime than in the corrugated flamelets regime. However, the ratio of second law efficiency under turbulent conditions to its corresponding laminar value does not get significantly affected by the regime of combustion, as viscous dissipation plays a marginal role in the overall entropy generation in premixed flames.
Keywords: direct numerical simulations; entropy generation; viscous diffusion; chemical reaction; thermal conduction; mass diffusion

Article Statistics

Load and display the download statistics.

Citations to this Article

Cite This Article

MDPI and ACS Style

Farran, R.; Chakraborty, N. A Direct Numerical Simulation-Based Analysis of Entropy Generation in Turbulent Premixed Flames. Entropy 2013, 15, 1540-1566.

AMA Style

Farran R, Chakraborty N. A Direct Numerical Simulation-Based Analysis of Entropy Generation in Turbulent Premixed Flames. Entropy. 2013; 15(5):1540-1566.

Chicago/Turabian Style

Farran, Richard; Chakraborty, Nilanjan. 2013. "A Direct Numerical Simulation-Based Analysis of Entropy Generation in Turbulent Premixed Flames." Entropy 15, no. 5: 1540-1566.

Entropy EISSN 1099-4300 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert