面向空间受限燃烧场碳烟浓度测量的双色-沙姆激光诱导炽光技术研究

Two-color-Scheimpflug laser-induced incandescence technique for soot concentration measurements in space-limited combustion field

  • 摘要: 针对航空发动机燃烧室出口等复杂、空间受限环境下的燃烧流场碳烟浓度分布测量需求,本文开发了双色-沙姆激光诱导炽光(Two-Color-Scheimpflug Laser-Induced Incandescence, 2C-Scheimpflug LII)技术及测量系统,通过倾斜焦面拍摄的方式获取碳烟体积分数分布图像。首先在McKenna、Gülder、Santoro这3种典型乙烯/空气火焰的特定工况下对所开发技术和测量系统开展了验证实验,并与国内外同行在相同工况下获得的测量结果进行对比,证明了该双色-沙姆激光诱导炽光测量系统的有效性。标准火焰测试结果表明,该系统的碳烟体积分数测量下限约为2.0 × 10−9。在此基础上,利用双色-沙姆激光诱导炽光技术测量了某型单头部双旋流航空发动机模型燃烧室出口横向截面及燃烧室内部纵向截面的碳烟体积分数空间分布。初步研究结果显示:燃烧室出口的碳烟体积分数分布呈现出高度的瞬时性和随机性,而燃烧室内部的碳烟体积分数分布则呈V形分布。

     

    Abstract: To address the need for measuring soot concentration distributions in complex and spatially constrained combustion flow fields, such as the outlet of aero-engine combustors, this study developed the Two-color-Scheimpflug Laser-Induced Incandescence (2C-Scheimpflug LII) technique and a corresponding measurement system, which obtains soot volume fraction distribution images by employing an oblique imaging method. The technique and measurement system validation experiments were first conducted under specific conditions using three typical ethylene/air flames (McKenna, Gülder, and Santoro). Comparisons with measurement results obtained by other researchers under the same conditions demonstrate the feasibility of the 2C-Scheimpflug LII system. The test results in standard flames show that the lower detection limit of soot volume fraction measurements of our system is approximately 2.0 × 10−9. Further, the 2C-Scheimpflug LII technique was applied to measure the spatial distribution of soot volume fractions at the transverse cross-section of the outlet and the longitudinal section of a single-sector, dual-swirler aero-engine model combustor. The preliminary results show that the soot volume fraction distribution at the combustor outlet exhibits high instantaneous variability and randomness, while within the combustor, the soot volume fraction displays a V-shaped distribution.

     

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