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Impact of pressure fluctuations on the dynamics of laminar premixed flames

Beardsell, Guillaume and Blanquart, Guillaume (2018) Impact of pressure fluctuations on the dynamics of laminar premixed flames. Proceedings of the Combustion Institute, 37 (2). pp. 1895-1902. ISSN 1540-7489. http://resolver.caltech.edu/CaltechAUTHORS:20181010-083802365

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Abstract

Thermo-acoustic instabilities are problematic in the design of continuous-combustion propulsion systems such as gas turbine engines, rocket motors, jet engine afterburners, and ramjets. Conceptually, the coupling between acoustics and flame dynamics can be divided into two categories: flame area fluctuations and changes in the local flame speed. The latter can be caused by the thermodynamic fluctuations that accompany an acoustic wave. This coupling is the focus of the present work. In this paper, we are concerned with the dynamics of laminar premixed flames involving large hydrocarbon species. Through high-fidelity numerical simulations, we investigate the flame response for a wide range of fuels and acoustic frequencies. The combustion of hydrogen and methane is considered for verification purposes and as baseline cases for comparison with two large hydrocarbon fuels, n-heptane and n-dodecane. We extract the phase and gain of the unsteady heat release response, which are directly related to the Rayleigh criterion and thus the stability of the system. For all fuels, we observe a local peak in the heat release gain. At high frequencies, we find that the fluctuations of the different species mass fractions decrease with the inverse of the acoustic frequency, leading to chemistry being “frozen” in the high-frequency limit. This allows us to predict the flame behavior directly from the steady-state solution.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.proci.2018.07.125DOIArticle
ORCID:
AuthorORCID
Beardsell, Guillaume0000-0001-7138-488X
Blanquart, Guillaume0000-0002-5074-9728
Additional Information:© 2018 The Combustion Institute. Published by Elsevier Inc. Received 1 December 2017, Revised 15 May 2018, Accepted 6 July 2018, Available online 9 October 2018.
Subject Keywords:Laminar flames; Thermo-acoustic instabilities; Direct numerical simulations; Detailed chemistry
Record Number:CaltechAUTHORS:20181010-083802365
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20181010-083802365
Official Citation:Guillaume Beardsell, Guillaume Blanquart, Impact of pressure fluctuations on the dynamics of laminar premixed flames, Proceedings of the Combustion Institute, Volume 37, Issue 2, 2019, Pages 1895-1902, ISSN 1540-7489, https://doi.org/10.1016/j.proci.2018.07.125.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90221
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:10 Oct 2018 16:15
Last Modified:29 Jan 2019 16:56

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