2015-10-292015-10-292015-07-12ICES-2015-204http://hdl.handle.net/2346/64475Bellevue, WashingtonJohn E. Brooker, NASA John H. Glenn Research Center, USADaniel L. Dietrich, NASA John H. Glenn Research Center, USASuleyman A. Gokoglu, NASA John H. Glenn Research Center, USADavid L. Urban, NASA John H. Glenn Research Center, USAGary A. Ruff, NASA John H. Glenn Research Center, USAThe 45th International Conference on Environmental Systems was held in Bellevue, Washington, USA on 12 July 2015 through 16 July 2015.An accidental fire inside a spacecraft is an unlikely, but very real emergency situation that can easily have dire consequences. While much has been learned over the past 25+ years of dedicated research on flame behavior in microgravity, a quantitative understanding of the initiation, spread, detection and extinguishment of a realistic fire aboard a spacecraft is lacking. Virtually all combustion experiments in microgravity have been small-scale, by necessity (hardware limitations in ground-based facilities and safety concerns in space-based facilities). Large-scale, realistic fire experiments are unlikely for the foreseeable future (unlike in terrestrial situations). Therefore, NASA will have to rely on scale modeling, extrapolation of small-scale experiments and detailed numerical modeling to provide the data necessary for vehicle and safety system design. This paper presents the results of parallel efforts to better model the initiation, spread, detection and extinguishment of fires aboard spacecraft. The first is a detailed numerical model using the freely available Fire Dynamics Simulator (FDS). FDS is a Computational Fluid Dynamics (CFD) code that numerically solves a large-eddy simulation form of the Navier-Stokes equations. FDS provides a detailed treatment of the smoke and energy trans- port from a fire. The simulations provide a wealth of information, but are computationally intensive and not suitable for parametric studies where the detailed treatment of the mass and energy transport are unnecessary. Application of this model to define flow conditions for the Spacecraft Fire Experiment (Saffire) in Orbital’s Cygnus vehicle is presented in the paper. The second path extends a model previously documented at ICES meetings that at- tempted to predict maximum survivable fires aboard spacecraft. This one-dimensional model simplifies the heat and mass transfer as well as toxic species production from a fire. These simplifications result in a code that is faster and more suitable for parametric studies. The paper discusses a case study applying this model to assist hatch design for the Multi-Purpose Crew Vehicle (MPCV) and shows that the Cabin Pressure Equalization (CPE) valve could prevent cabin over-pressurization (enabling hatch opening by the crew) for reasonable fire scenarios. The overall goal of this work is to develop these two models as complementary tools. The FDS model will enable extrapolating Saffire experiment results to other vehicles and will help in verification of future vehicle safety plans. The one-dimensional model is helpful for rapid parametric studies of design options.application/pdfengPresentation