Suppression of Flame Wrinkling by Buoyancy: The Baroclinic Stabilization Mechanism
Suppression of Flame Wrinkling by Buoyancy: The Baroclinic Stabilization Mechanism
复制标题
通过浮力抑制火焰起皱：斜压稳定机制
DOI：
10.2514/2.534
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发表时间：
1998
期刊：
影响因子：
2.5
通讯作者：
J. Driscoll
中科院分区：
文献类型：
--
作者：
J. Sinibaldi;C. Mueller;A. E. Tulkki;J. Driscoll
众所周知，浮力可以通过改变火焰的起皱过程来改变湍流火焰的燃烧速度。为了量化浮力如何放大或减弱皱纹，通过使皱纹与涡流相互作用，在预混合的皱纹中产生已知尺寸和幅度的可重复皱纹。皱纹幅度的图像是在 NASA 刘易斯研究中心 2.2-s 落塔和 1-g 条件下的微重力条件下获得的。热扩散稳定和不稳定的情况都被考虑。结果量化了浮力抑制皱纹的程度；当去除浮力时，微重力 e ames 的褶皱幅度比 1 g e ames 大 2 ‐3 倍。由于扩散不稳定的情况比稳定的情况具有更大的皱纹幅度，因此还观察到火焰拉伸效应。粒子成像测速速度数据表明，由于浮力而出现两种稳定机制：传统的瑞利-泰勒机制和斜压稳定机制，这在燃烧过程中以前没有观察到。测量表明，电涡流会产生新的涡度，而电涡流产生的涡度有助于抑制电涡流的起皱。
Buoyancy forces are known to alter the burning velocity of a turbulent e ame by modifying the e ame wrinkling process. To quantify how e ame wrinkles are amplie ed or attenuated by buoyancy, a repeatable wrinkle of known size and amplitude is created in a premixed e ame by interacting the e ame with a vortex. Images of the wrinkle amplitude were obtained for microgravity conditions in the NASA Lewis Research Center 2.2-s drop tower and for 1-g conditions. Both thermodiffusively stable and unstable cases were considered. Results quantify the degree to which buoyancy suppresses the e ame wrinkling; when buoyancy is removed, the microgravity e ames have a wrinkle amplitude that is 2 ‐3 times greater than 1- g e ames. Flame stretch effects also are observed because the diffusionallyunstablee ameshavelargerwrinkleamplitudesthanthestablecases.Theparticleimagingvelocimetry velocity data show that two stabilizing mechanisms occur due to buoyancy: the conventional Rayleigh ‐Taylor mechanism and a baroclinic stabilization mechanism, which has not been observed previously in combustion processes. Measurements show that the e ame generates new vorticity, and this e ame-generated vorticity can help to suppress the e ame wrinkling.