Measurement of temperature and temperature profile of an axisymmetric gaseous flames using Lau phase interferometer with linear gratings

We have investigated the utility of a Lau phase interferometer with circular gratings and a white-light source to measure the temperature and temperature profile of an axisymmetric flame. The temperature measured with a Lau phase interferometer is in good agreement with the temperature measured with a thermocouple and multilogger. Detailed theoretical analysis and experimental investigation are presented.

Measurement of temperature profile of a gaseous flame with a Lau phase interferometer that has circular gratings

A shearing interferometer is used to measure the temperature and temperature profile inside the axisymmetric flame of a Bunsen burner and the two-dimensional flame of a slot burner used in an atomic absorption spectrophotometer. Experimentally obtained results are compared with the results measured with a platinum–platinum-rhodium thermocouple and multilogger. The values are in good agreement. The effect of aspiring water through the nabulizer on the temperature profile of the slot burner is also presented.

Measurement of the temperature of a gaseous flame using a shearing plate

Two methods of temperature field reconstruction starting from refractive index map obtained with Moire deflectometry in downward flame spread along cylindrical PMMA samples have been compared, in order to determine their suitability in this kind of combustion problems, i.e., diffusive flames on solids. This article shows the applicability of the method based on the hypothesis of the same functional behaviour (SFB) of all the variables representing the flow, which provides a good picture of the temperature field. However, the method based on numerical solutions of the Navier–Stokes equations with simple chemical kinetics, suitable for other purposes, does not provide reliable quantitative results when it is used for the computation of the spatial variation of the Gladstone–Dale (G-D) constant and the gas constant, and for the later evaluation of the temperature from the refractive index map.

TEMPERATURE FIELD RECONSTRUCTION FROM PHASE-MAP OBTAINED WITH MOIRé DEFLECTOMETRY IN DIFFUSION FLAME ON SOLIDS

The paper discusses the principles of optical testing of transparent objects using the Talbot images method and its applicability to diagnostic of flames. The experimental study was performed for premixed methane–air flame formed by an axisymmetric nozzle. The local deflection angles of the probe radiation were determined from measurements of the relative displacements of intensity maxima of the Talbot image which is caused by passing of light through the flame. The Abel integral equation was solved to reconstruct the refractive index distribution in the flame. Calculation of the temperature field from the refractive index data was based on neglecting the spatial variation of the component composition. Inaccuracy of the calculations was evaluated by comparing the results with the thermocouple measurements. The results demonstrate that the Talbot images method can be used to measure the temperature distribution in axisymmetric reacting gas flows with high spatial resolution.

Temperature measurements in an axisymmetric methane–air flame using Talbot images

An experimental study of the flame zone around an n-hexane fuel droplet burning in air is presented here. The results are compared with the burning characteristics of a methanol droplet. The basic principle of Moire Deflectometry system which was employed to study the burning behavior of the droplet diffusion flame is explained. The temperature results are presented in the form of radial graphs and isotherms.

D. K. Sharma

Papers

Structure of Burning n-hexane Droplet by Moiré Deflectometry