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首页> 外文会议>US National Combustion Meeting >Simulation of 2D Tomographic TDLAS using Algebraic Reconstruction and Tikhonov Regularization
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Simulation of 2D Tomographic TDLAS using Algebraic Reconstruction and Tikhonov Regularization

机译：使用代数重建和Tikhonov规则仿真2D断层摄影TDLA

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Tomographic techniques allow for the reconstruction of spatially varying temperature and concentration fields in a flame from line-of-sight integrated tunable diode laser absorption spectroscopy (TDLAS) measurements. Such methods generally need data taken from a large number of view angles to gather as much directional information about the property distribution inside the flame as possible. Often, optical access for such measurements is limited, which poses substantial problems for conventional to-mographic methods. In recent years, hyper-spectral approaches have shown promising results, where the lack of directional information is compensated by increased spectral information from wide-band tunable lasers. This work uses an alternative approach for tomographic reconstruction that uses conventional DFB diode lasers with narrow tunability, which are commonly used for line-of-sight TDLAS measurements. Specifically, the feasibility of performing limited-view tomographic reconstruction using tunable diode laser absorption spectroscopy (TDLAS) for temperature and concentration of water vapor in a stationary flame is addressed. Simulated TDLAS line-of-sight (LOS) data consist of second harmonic peak heights (2f) obtained from wavelength modulation. Ratio thermometry from two-transition technique is used to infer local temperature and concentration of the species in the flame. Integrated absorption measurements in the near-IR region (6930 cm~(-1) to 6940 cm~(-1) range) are simulated to obtain projection values from tomography. Spectroscopic parameters such as line-strengths, transition wave numbers, collisional broadening coefficients and coefficients for their temperature dependency are taken from the HITRAN 2008 database. Two tomographic de-convolution methods are chosen - a) a multiplicative algebraic reconstruction technique (MART), which is known to perform much better than traditional filtered-backprojection algorithms in case of limited-view tomo-synthesis and b) a Tikhonov regularized tomographic inversion. In both cases, tomographic algorithms are used to reconstruct local 2f peak height distribution for two spectroscopic transitions and temperature and concentration of water vapor are determined and compared to assumed model distributions.
机译：断层技术允许从视域综合可调二极管激光吸收光谱（TDLA）测量的VOLAME中的空间变化温度和浓度区域的重建。这些方法通常需要从大量视角所采取的数据来收集关于火焰内部的属性分布的定向信息。通常，用于这种测量的光学访问是有限的，这对传统的Mographic方法构成了大量问题。近年来，超光谱方法已经显示了有希望的结果，其中通过从宽带可调激光器的频谱信息增加了缺乏方向信息。这项工作采用替代方法来进行断层切断重建，该转换重建使用具有窄可调性的传统DFB二极管激光器，这通常用于视线TDLAS测量。具体地，解决了使用可调谐二极管激光吸收光谱（TDLA）进行限流的电气吸收光谱（TDLA）在固定火焰中进行温度和水蒸气浓度的可行性。模拟TDLAS的视线（LOS）数据包括从波长调制获得的二次谐波峰值高度（2F）组成。两种过渡技术的比率测温用于推断火焰中局部温度和物种的浓度。模拟近红外区域（6930cm〜（-1）至6940cm〜（-1）范围）的集成吸收测量以获得断层扫描的投影值。从HITRAN 2008数据库中取出诸如线强度，过渡波数，碰撞扩大系数和系数的线强度，转变波数，碰撞拓宽系数和系数。选择了两个断层扫描方法 - a）乘法代数重建技术（MART），已知在有限的粒子合成和B）的情况下，在有限的视图致致扭曲的算法和B）的情况下，该乘法代数重建技术（MART）比传统的滤波 - 反射算法更好。 。在这两种情况下，用于重建断层算法来重建局部2F峰值高度分布，并且确定并将水蒸气的温度和浓度与假设的模型分布进行比较。

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