Measuring heat flux to a porous burner in microgravity

Abstract

Flame heat flux absorbed by a porous gas-fueled burner is measured in microgravity. The burner's perforated copper plate serves as a slug calorimeter in which two heat flux thermopile sensors are embedded. The slug calorimeter provides the average heat flux over the burner surface as a function of time. The 25 mm diameter burner is calibrated as a slug calorimeter in normal gravity using a known radiative heat flux with step changes. Microgravity diffusion flames were observed in NASA Glenn's 5.18-s Zero Gravity Research Facility, and average heat fluxes measured with the calorimeter agree with the locally measured heat fluxes through a theoretical distribution function. The results show that the average slug calorimeter heat flux and the two local heat flux measurements are in harmony over a wide range of microgravity flame fluxes ranging from 5–20 kW/m2, with the edge heat flux much higher. Transient and nearly steady results are presented.