The present investigation is focused on high-frequency combustion instabilities coupled by transverse acoustic modes. This phenomenon has been observed during the development of many liquid rocket engines and other high performance devices. Such instabilities induce an unsteady heat release which leads in many cases to a rapid intensification of heat fluxes to the thrust chamber walls, causing fatal damage and a spectacular destruction of the propulsion system. One central objective of this effort is to observe and understand the physical processes leading the coupling between acoustics and combustion, and resulting in the growth of such instabilities. Experiments carried out on the Mascotte testbed at ONERA serve to identify the main processes involved and bring forth mechanisms taking place when an engine becomes unstable. Hot fire experiments are carried out in a model scale combustor reproducing many of the conditions prevailing in unstable rocket engines. Subcritical and transcritical cryogenic jets are injected in a multiple injector combustion chamber (MIC). This system is fed with LOx and methane through five injection units. The flames formed in this configuration are modulated by an acoustic wave with an amplitude of several bars. This is obtained with a new Very Large Amplitude Modulator (VHAM) capable of generating acoustic mode amplitudes representative of those found in actual engine undergoing HF instabilities. It is shown first that the strength of the acoustic field and the frequency range of oscillation (1 kHz–3.5 kHz) are consistent with rocket instability observations. Conditions where a feedback of the flame on the acoustic field occurs are obtained. High speed diagnostics indicates that the velocity field dramatically enhances the atomization process. The liquid core length is strongly reduced. At moderate amplitudes, the liquid jets are flattened in the spanwise direction and heat release takes place in two sheets neighboring the dense core of oxygen. At higher amplitudes the core size is diminished and the flame pattern is considerably more compact. It is also shown that the flames are periodically displaced by the acoustic field and an alternate pattern of liquid oxygen appears in the chamber. An oscillation of the oxygen distribution in the transverse direction of the chamber is observed.
Yoann Méry 1, 2 ; Layal Hakim 1, 2 ; Philippe Scouflaire 1, 2 ; Lucien Vingert 3 ; Sébastien Ducruix 1, 2 ; Sébastien Candel 1, 2
@article{CRMECA_2013__341_1-2_100_0, author = {Yoann M\'ery and Layal Hakim and Philippe Scouflaire and Lucien Vingert and S\'ebastien Ducruix and S\'ebastien Candel}, title = {Experimental investigation of cryogenic flame dynamics under transverse acoustic modulations}, journal = {Comptes Rendus. M\'ecanique}, pages = {100--109}, publisher = {Elsevier}, volume = {341}, number = {1-2}, year = {2013}, doi = {10.1016/j.crme.2012.10.013}, language = {en}, }
TY - JOUR AU - Yoann Méry AU - Layal Hakim AU - Philippe Scouflaire AU - Lucien Vingert AU - Sébastien Ducruix AU - Sébastien Candel TI - Experimental investigation of cryogenic flame dynamics under transverse acoustic modulations JO - Comptes Rendus. Mécanique PY - 2013 SP - 100 EP - 109 VL - 341 IS - 1-2 PB - Elsevier DO - 10.1016/j.crme.2012.10.013 LA - en ID - CRMECA_2013__341_1-2_100_0 ER -
%0 Journal Article %A Yoann Méry %A Layal Hakim %A Philippe Scouflaire %A Lucien Vingert %A Sébastien Ducruix %A Sébastien Candel %T Experimental investigation of cryogenic flame dynamics under transverse acoustic modulations %J Comptes Rendus. Mécanique %D 2013 %P 100-109 %V 341 %N 1-2 %I Elsevier %R 10.1016/j.crme.2012.10.013 %G en %F CRMECA_2013__341_1-2_100_0
Yoann Méry; Layal Hakim; Philippe Scouflaire; Lucien Vingert; Sébastien Ducruix; Sébastien Candel. Experimental investigation of cryogenic flame dynamics under transverse acoustic modulations. Comptes Rendus. Mécanique, Volume 341 (2013) no. 1-2, pp. 100-109. doi : 10.1016/j.crme.2012.10.013. https://comptes-rendus.academie-sciences.fr/mecanique/articles/10.1016/j.crme.2012.10.013/
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