Images of Local Propagation Speeds and Stretch Rates of Turbulent Premixed Flames to Improve Numerical Models

用于改进数值模型的湍流预混火焰的局部传播速度和拉伸率图像

• 批准号: 9904198
• 负责人: James Driscoll
• 金额: $ 31.5万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2002-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9904198&HistoricalAwards=false
• 关键词: Images; Local; Propagation; Speeds; Stretch

ABSTRACTJAMES F. DRISCOLL CTS-9904198This is an experimental study to quantify, for the first time, the local propagation speed along the surface of a turbulent, premixed flame. As bulges and cusps form on the wrinkled flame surface, certain flame segments propagate forward at unusually large speeds. A PIV-PLIF ( particle imaging velocimetry- planar laser induced fluorescence) diagnostic has been used to measure propagation speed for an unsteady, curved, two-dimensional laminar flame that undergoes a flame-vortex interaction. In this study, this technique is extended to the three-dimensional (3-D) flame case by using two sets of orthogonal laser light sheets. The effort includes (a) measurements of local propagation speed along a turbulent flame surface; (b) measurements of 3-D flame stretch rates; (c) identification of cusps and bulges in the flame front that yield abnormally large local propagation speeds and investigation of the physical reasons for these abnormalities; images allow correlation of fast flame propagation with the presence of a vortex, with flame curvature, or with the sharing of radicals between flame segments; (d) comparison of measured propagation speeds to those from advanced direct numerical simulations (DNS) from various groups; and to those predicted by the Theory of Flame Stretch.Local propagation velocity is the key quantity that must be correctly modeled in order to develop large-eddy simulations (LES) of premixed and partially premixed combustion. Such models offer the possibility of major new breakthroughs in turbulent combustion, including the development of low-polluting gas-turbine and internal-combustion engines.

这是一项实验研究，首次量化了沿湍流预混火焰表面的局部传播速度。当凸起和尖头在起皱的火焰表面形成时，某些火焰段以异常大的速度向前传播。PIV-PLIF（粒子成像测速-平面激光诱导荧光）诊断方法用于测量非定常、弯曲的二维层流火焰的传播速度，该火焰经历了火焰-涡相互作用。在本研究中，通过使用两组正交激光光片，将该技术扩展到三维火焰情况。工作包括(a)测量沿湍流火焰表面的局部传播速度；(b)三维火焰拉伸率测量；(c)识别火焰锋面产生异常大的局部传播速度的尖头和凸起，并调查这些异常的物理原因；图像允许快速火焰传播与漩涡的存在，火焰曲率或火焰段之间的自由基共享相关；(d)测量的传播速度与来自不同组的先进直接数值模拟（DNS）的传播速度的比较；以及火焰拉伸理论预测的结果。局部传播速度是进行预混合和部分预混合燃烧大涡模拟必须正确建模的关键参数。这些模型为湍流燃烧的重大新突破提供了可能，包括低污染燃气轮机和内燃机的发展。