Flow field measurements of pulverized coal combustion using optical diagnostic techniques
Flow field measurements of pulverized coal combustion using optical diagnostic techniques
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DOI：
10.1007/s00348-013-1534-2
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发表时间：
2013-05
影响因子：
2.4
通讯作者：
S. Balusamy;A. Schmidt;S. Hochgreb
中科院分区：
文献类型：
--
作者：
S. Balusamy;A. Schmidt;S. Hochgreb
本文介绍了激光多普勒测速(LDV)和粒子图像测速(PIV)技术在煤粉颗粒反应流中的应用。利用实验室规模的开口式环形燃烧器产生了煤粒和微米氧化铝颗粒的速度分布。成对双分量LDV测量和高速立体声PIV测量提供了流场的三维速度分量。对氧化铝和煤粒播撒速度的详细比较表明，不同的速度是由于煤粒的大小分布造成的。此外，与煤粒燃烧相关的非球形和高火焰光度给Mie散射图像带来了噪声。用LDV和PIV技术测量的平均速度和均方根速度的比较表明，PIV测量受到煤粒宽尺寸分布的影响，而LDV测量则偏向于小颗粒的速度，因为来自大颗粒的信号被剔除了。这种小粒子偏差也反映在两种技术的光谱特性上，在可获得的频率范围内，这两种技术的光谱特性非常一致。PIV测量表明，大颗粒煤颗粒对湍流波动没有预期的响应。LDV和PIV测量之间的总体良好一致性表明，高速PIV技术适用于含有颗粒的高光度煤火焰，同时也突出了其一些局限性。
This paper demonstrates the application of laser Doppler velocimetry (LDV) and particle image velocimetry (PIV) techniques to a particle-laden reacting flow of pulverized coal. A laboratory-scale open-type annular burner is utilized to generate velocity profiles of coal particles and micrometric alumina particles. Pair-wise two-component LDV measurements and high-speed stereo PIV measurements provide three-dimensional velocity components of the flow field. A detailed comparison of velocities for alumina and coal particle seeding revealed differences attributed to the wide size distribution of coal particles. In addition, the non-spherical shape and high flame luminosity associated with coal particle combustion introduces noise to the Mie scatter images. The comparison of mean and RMS velocities measured by LDV and PIV techniques showed that PIV measurements are affected by the wide size distribution of coal particles, whereas LDV measurements become biased toward the velocity of small particles, as signals from large particles are rejected. This small-particle bias is also reflected in the spectral characteristics for both techniques, which are in good agreement within the range of frequencies accessible. PIV measurements showed an expected lack of response of large coal particles to the turbulence fluctuations. The overall good agreement between LDV and PIV measurements demonstrates the applicability of the high-speed PIV technique to a particle-laden, high luminosity coal flame while highlighting some of its limitations.