Temperature Measurement in Conical Flames by Laser Interferometry

Abstract

Reasons are developed for choosing a laser interferometer, and in particular the design due to Murty, to undertake flame temperature measurements in small-scale conical flames. The difficulties of obtaining a simple polynomial to represent the fringe shift distribution for an axisymmetric diffusion flame are discussed and a method of solution using the extended spline fit technique is described. The organisation of computer programs to plot fringe shift profiles and to compute radial distributions of refractivity and final temperature is given. The technique is applied to a methane diffusion flame and a comparison made with results obtained using a fine-wire thermocouple. The paper concludes that the technique is especially suitable where lateral fringe shift distributions are complex functions of lateral distance and in particular gives flame temperature profiles completely compatible with the more conventional probe methods.