Perturbations of the flame structure due to a thermocouple. I. Experiment

In thermocouple measurements in flames of gaseous or condensed systems, it is usually assumed that due to the small sizes of thermocouples, the flame perturbations caused by thermocouples are negligible. It is shown, however, that these perturbations can be significant. Temperature measurements in a laminar methane flame at atmospheric pressure revealed a systematic overestimation of measured temperatures compared with the temperature of the unperturbed flame in the temperature gradient region and in the region of the maximum concentration of radicals. This overestimation was measured, and its causes were analyzed. Previously, such effects have not been studied in the literature.