Absorption Thermometry and Surface Dynamics of POM and PMMA in a Crossflow Burner

A solid fuel crossflow burner with no rearward-facing step, and with flame holding at the leading edge of the solid fuel grain, was manufactured and used to measure the global regression rates of POM and PMMA for a range of standard air flow rates. The burner produced steady burning conditions for both polymers at varied standard air flow rates. Tunable diode laser absorption spectroscopy of water was used to characterize the water mole fraction and temperature during the burning of PMMA, demonstrating the ability to resolve the fuel-rich and oxidizer-rich regions and capture the unsteadiness associated with the PMMA flame. The absorption path length was varied in height to measure the effects of increased measurement standoff from the flame on the water temperature, mole fraction, and variance for single laser scans. High-magnification imaging was performed on both the post-burned and actively burning polymer samples to identify trends in the quantity and size of bubbles and craters found on or underneath the surface of the polymers.