Solid propellant combustion studies at high pressures (500–50,000 psi) must be conducted with a high spatial resolution in order to resolve the species concentration and flame temperature profiles. Such studies are often performed in specifically designed experimental facilities, including chimney-type strand burners. To successfully carry out FT-IR emission spectrometry of products from the combustion of small propellant strands, one is required to perform a critical assessment of the achievable signal-to-noise ratio (SNR). In this work, an analytical expression for the SNR of FT-IR emission spectrometry limited to detector noise has been derived. The expression is specifically applied for the ν3 fundamental band of CO2 and in the optically thick limit verified by experiments. The results from the application of the theory show that a spatial resolution on the order of 200 μm should yield SNRs of 100 or larger at the center of the considered band for the anticipated temperatures of high-pressure solid propellant combustion. Measurements of emission spectra of combustion products of a homogeneous solid propellant, NO-SOL-363, have also been performed at one atmosphere total pressure to show that an 800-jun spatial resolution may be sufficient to deduce species concentration and temperature profiles.
