Temperature measurement of dilute hydrogen flame by digital laser-speckle technique

Abstract

In this paper, temperature measurement of axisymmetric dilute hydrogen flame is described using digital laser-speckle technique, which allows the measurement of refractive index field of the flame without any tracers. The measurement system consists of laser and CCD camera, which are placed in-line configuration. The temperature field of the flame is derived from the refractive index field using the cross-correlation analysis of the speckle pattern with and without flame. The influence of the species፧concentration on the temperature measurement is evaluated from the gas composition in the flame using gas chromatography. It is found that the temperature field measured by the present method with concentration correction agrees with that of the thermocouple measurement within an experimental accuracy, suggesting the usefulness of this measurement technique.

Measurement of temperature distribution for the flickering phenomenon around the premixed flame by using laser speckle method

“…The equivalence ratio is 0.95. The temperature distribution in the premixed flame is measured by using the laser speckle method (Fujisawa et al 2009). The light of the argon ion laser, whose noise is cut by a special filter, is dispersed by ground glass.…”

“…The displacement between the speckle patterns with the flame and without the flame is calculated by the PIV method. The temperature distribution is calculated by using the movement distance and the following Gladstone-Dale's equation (Fujisawa et al 2009). …”

“…In this paper, the time course of the temperature field around the premixed flame has been measured by using the laser speckle method (Fujisawa et al 2009) with high-speed camera, paying attention to the flickering.…”

Simultaneous measurement of temperature and color spectrum of axisymmetric premixed flames using digital laser speckle photography and an image processing approach

“…Optical techniques for measuring flame temperature, an important characteristic to determine the performance of a combustion process, includes two-color pyrometry [2]; imaging three-color [3], schlieren [4,5], shadowgraph [4], laser speckle photography [6][7][8][9][10], digital holography [11][12][13], interferometric [14,15] and laser-induced fluorescence methods [16][17][18]. Another essential feature extensively used for combustion diagnostic has been chemiluminescence since it provides chemical information of the combustion processes and can be used to obtain the parameters for the burner conditions, too [18][19][20][21][22][23][24][25][26][27][28].…”

“…On the whole, to measure temperature, one requires complicated and costly optical arrangements and a vibrationfree system to establish the temperature fields [11][12][13][14][15][16][17]. Yet, there are well-established speckle methods used for measuring in-plane displacements [6][7][8][9][10]29], particularly digital laser speckle photography (DLSP) is a low cost, easy to implement, with variable sensitivity and little vibrations sensitivity. What this method does, is measure the flow refractive index change.…”