Burning rate estimation based on flame evolution in a channel

Abstract

Non-stationary modes of gaseous fuel combustion are of paramount importance for their efficient and safe usage in the space industry. The paper analyzes experimental and numerical data on the early stages of flame propagation in channels of different widths. It is demonstrated that there is a self-similar behavior of flame development at least at the considered stages. Qualitatively flame acceleration proceeds exponentially in channels of different widths, though the particular acceleration increment is inversely proportional to the width of the channel. Exponential acceleration is related to the positive feedback between the flame and flow dynamics, while the previous stage is associated mainly with the flame propagation induced by the expansion of combustion products. Based on the analysis of experimental data, one can estimate both the time instant at which the exponential stage starts and the increment of exponential acceleration, which in turn depends unambiguously on the normal burning rate. As a result, a novel technique for normal burning rate determination with the use of a channel reactor can be proposed.