Experimental and Numerical Study of Infrared (IR) Emission from a Porous Radiant Burner

摘要

An experimental analysis and computational modelling of thermal radiation from an INCONEL601 wire-mesh porous burner has been conducted. It has been found that within a bandwidth between 2 microns and 20 microns, the infrared radiation in the 2-5 microns waveband is the dominant band. Optimal operating conditions, as determined by the surface temperature and radiant intensity, are a function of the equivalence ratio and the firing rate. The location of the flame front is also influenced by these parameters. For fuel- rich mixtures the flame is usually located above the surface and the flame stability is sensitive to external perturbations. A maximum surface temperature of approximately 1223K, and a radiation intensity of 50 W/Sr, has been measured. It has also been shown that INCONEL601, despite its high emissivity, can be used as an effective radiation shield. By placing a piece of the wire- mesh in front of burning MTV pyrotechnic composition, the infrared radiation was significantly reduced. The equivalent black body temperature of MTV was cut from approximately 1900 deg. C without a shield to approximately 1400 deg. C with a shield adjacent to the mixture. A comparison between the ChemRad model predictions and measured surface temperature for various equivalence ratios has shown a reasonable agreement with a maximum discrepancy of 16% for fuel-rich mixtures. However, within optimal operating conditions of the burner (equivalence ratio 0.8-1) a maximum difference of 8% has been observed. Accounting for the variability in the measurements, the number of simplifying assumptions and the uncertainty in some values of the physical and optical properties, the accuracy and consistency of the model, as a first-order approximation is acceptable.