Large eddy simulations of multiple transcritical coaxial flames submitted to a high-frequency transverse acoustic modulation
Large eddy simulations of multiple transcritical coaxial flames submitted to a high-frequency transverse acoustic modulation
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DOI：
10.1016/j.proci.2014.05.142
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发表时间：
2015-01-01
影响因子：
3.4
通讯作者：
Candel, S.
中科院分区：
文献类型：
--
作者：
Hakim, L.;Ruiz, A.;Candel, S.
本文对多个低温射流火焰与高频横声波模式相互作用的动力学进行了数值研究。这项研究的动机是与液体火箭发动机的高频不稳定性有关的许多问题。大涡模拟是在一个复杂的流动形态中进行的，这种流动形态是湍流的、反应性的、跨临界的，并且没有或存在大幅度的声学运动。几何形状是模型比例实验构型的几何形状。利用高端计算资源获得的结果证明了这种计算的可行性，提供了对耦合过程的洞察，展示了在实验中发现的特征，并补充了实验数据。根据声学环境(以速度或压力振荡为主)，可以观察和分析低温射流和火焰的选择性响应。研究发现，当火焰与横向声学运动相互作用时，火焰更加致密，致密的核心长度显著减少。在跨度方向上，火焰和致密的核心是平坦的，这一特征也在实验中发现。实验观测到的非定常运动在数值上得到了很好的反演。这些模拟突出了可以在横模中馈送能量的机制，并对不稳定驱动过程提出了可能的描述。轻质甲烷射流受到声学运动的震动，在顶部和底部交替撞击稠密的氧气流。火焰产生的非定常热释放速率和相应的声学瑞利项因火焰位置的不同而不同。(C)2014年，燃烧研究所。爱思唯尔公司出版，版权所有。
This article describes a numerical investigation that explores the dynamics of multiple cryogenic jet flames interacting with high frequency transverse acoustic modes. This research is motivated by the numerous issues associated with high-frequency instabilities in liquid rocket engines. Large eddy simulations are carried out in a complex flow configuration which is turbulent, reactive, transcritical and in the absence or presence of a large-amplitude acoustic motion. The geometry is that of a model scale experimental configuration. Results obtained by exploiting high end computational resources demonstrate the feasibility of such calculations, provide insight in the coupling process, exhibit features which are found in experiments and complement the experimental data. Depending on the acoustic environment (dominated by velocity or pressure oscillations), selective responses of the cryogenic jets and flames can be observed and analyzed. It is found that the flames are more compact when they are made to interact with the transverse acoustic motion and that the dense core length is notably reduced. In the span-wise direction, the flames and dense cores are flattened, a feature which is also found in experiments. The unsteady motion observed experimentally is well retrieved numerically. The simulations highlight the mechanisms that can feed energy in the transverse mode and suggest possible descriptions of the instability driving process. The light methane jet is shaken by the acoustic motion and impacts the dense oxygen stream alternatively on its top and bottom sides. The unsteady heat release rate and the corresponding acoustic Rayleigh term produced by the flames prove to be different according to the flame position regarding the acoustic environment. (C) 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved.