Vehicle Modeling During the Burn Events in the Saffire VI Experiments

In order to design a fire-safe environment inside a spacecraft, knowledge of the transport of heat and combustion products in a reduced gravity environment is needed. After a resupply mission to the ISS, the Saffire project provided large-scale fire data in a microgravity environment inside of Northrup Grumman’s Cygnus vehicle. Solid materials were burned, including a thin cotton-based sample and thick thermoplastic samples, to study a large-scale fire’s effect on a spacecraft. Sensors were placed in Cygnus that measured temperature and species concentration at four different standoffs, as well as nadir and zenith locations. Pyrosim was used to develop a model to predict the three burn events from Saffire VI using inlet and outlet data from the Saffire payload. The convective heat transfer coefficient between the cargo and the cabin air that was previously calibrated in the Saffire V model was used to predict the temperature response in the Saffire VI burn events. Good predictions of the CO2 and temperature responses for the remote sensors throughout Cygnus were realized.