Rectangular heat source on a semi-infinite solid: an analysis of a thin film heat flux gage

A thin film flux gage has been developed for a series of combustion experiments. The gage was designed to provide both rapid response and long use time. Initial calibrations using standard techniques indicated large differences between the literature and the estimated properties. In order to calibrate this gage without resorting the destructive property measurements, an analytical model of the gage response to a step heating current was developed. The model is in the form of three algebraic expressions which correspond to the early, middle, and late time regimes. The expressions are used to provide a framework for least squares estimates of the gage parameters. There is very good agreement between the model and the experimental data. The estimated parameter values demonstrate good to excellent repeatability and good agreement with both new literature data dnd results from destructive property measurements.