基于光闪烁的烟气流速测量技术

Flue gas velocity measuring technology based on optical scintillation

介绍了一种利用颗粒物浓度场随机起伏引起的光闪烁测量工业烟气排放速度的光学测量技术及其数据处理方法。对湍流作用下,基于分离式双光路测量系统结构的光闪烁互相关进行了分析,得到了相关函数的理论表达式。采用单向循环链表的数据存储结构实现信号数据在时间域的滑动,同时满足了测量实时性和平均性的要求。使用快递傅里叶变换(FFT)计算光闪烁互相关,提出了一种应用高级矢量扩展(AVX)指令加速FFT的方法,在基于Intel i7处理器的计算平台上将FFT的计算速度提高了1倍。最后给出了光闪烁法用于工业现场烟气流速测量的结果,与使用皮托管测量的结果基本一致,证明了本文光学测量技术及其数据处理方法的有效性。

An optical measuring technology and its data processing method for the discharge velocity measurement of industrial flue gas are introduced, using the optical scintillation signals caused by the random fluctuations of particulate concentration field. Under the influence of turbulence, the cross correlation of optical scintillation signals, which is based on the separate double optical path measuring system structure,is analyzed, and the theoretical expression of the correlation function is acquired. The single circular linked list is adopted as the data accessing structure to implement the signal data sliding in time domain, and it can satisfy the requirements of real time and average simultaneously. The value of the optical scintillation cross correlation is calculated by the fast Fourier transform （FFT）. An implementation method of parallel one-dimensional FFT using advanced vector extensions （AVX） instructions is proposed, and the FFT calculating speed is doubled on the computing platform which is based on the Intel i7 CPU. Finally,the field test results show that the flow velocity measured by the proposed technique in this paper is consistent well with the value tested by Pitot tube. It verifies the effectivenesses of this optical measuring technology and its data processing method.