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Fully compressible simulations of the impact of acoustic waves on the dynamics of laminar premixed flames for engine-relevant conditions

Beardsell, Guillaume and Blanquart, Guillaume (2020) Fully compressible simulations of the impact of acoustic waves on the dynamics of laminar premixed flames for engine-relevant conditions. Proceedings of the Combustion Institute . ISSN 1540-7489. (In Press) https://resolver.caltech.edu/CaltechAUTHORS:20200803-071751419

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Abstract

Thermo-acoustic instabilities remain problematic in the design of propulsion systems such as gas turbine engines, rocket motors, and ramjets. They arise from the constructive interaction of heat release rate and acoustic pressure oscillations, and can result in increased noise and mechanical fatigue. In the present work, we are concerned with the flame response to the thermodynamic fluctuations that accompany an incident acoustic wave. The objective is to investigate the flame dynamics under engine-relevant conditions using high-fidelity numerical simulations and detailed chemical kinetics. The focus is placed on the combustion of hydrogen and n-heptane, as they are both of practical interest and behave very differently when subjected to acoustic waves. 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. We highlight the differences between results obtained using the fully compressible Navier-Stokes equations and the low Mach number approximation. The two simulation frameworks agree very well for acoustic wavelengths much larger than the flame thickness. However, they differ significantly at high frequencies. The gain erroneously reaches a plateau under the low Mach number approximation, while it decays to zero using the fully compressible framework. This difference is attributed to the spatial variations in the acoustic pressure, which are not captured by the low Mach number approximation.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.proci.2020.06.003DOIArticle
ORCID:
AuthorORCID
Beardsell, Guillaume0000-0001-7138-488X
Blanquart, Guillaume0000-0002-5074-9728
Additional Information:© 2020 The Combustion Institute. Published by Elsevier Inc. Received 8 November 2019, Revised 21 May 2020, Accepted 10 June 2020, Available online 22 July 2020.
Funders:
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Foster FoundationUNSPECIFIED
NSFCBET-1832548
Subject Keywords:Laminar flames; Thermo-acoustic instabilities; Direct numerical simulations; Detailed chemistry
Record Number:CaltechAUTHORS:20200803-071751419
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200803-071751419
Official Citation:Guillaume Beardsell, Guillaume Blanquart, Fully compressible simulations of the impact of acoustic waves on the dynamics of laminar premixed flames for engine-relevant conditions, Proceedings of the Combustion Institute, 2020, ISSN 1540-7489, https://doi.org/10.1016/j.proci.2020.06.003. (http://www.sciencedirect.com/science/article/pii/S1540748920300286)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104692
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:03 Aug 2020 16:01
Last Modified:03 Aug 2020 16:01

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