THE INVESTIGATOR OF THIS PROPOSAL PROF. STEPHEN D. TSE IS A CO-INVESTIGATOR ON THE STRUCTURE AND RESPONSE OF SPHERICAL DIFFUSION FLAMES PROGRAM FOR WHICH PROF. LAW AT PRINCETON UNIVERSITY IS THE PRINCIPAL INVESTIGATOR. THE GOAL OF THIS PROJECT IS TO GAIN FUNDAMENTAL UNDERSTANDING OF THE STRUCTURE AND DYNAMICS OF SPHERICAL ONE-DIMENSIONAL DIFFUSION FLAMES. THE OBJECTIVES OF THE PROJECT ARE: (I) TO INTERROGATE THE FIDELITY OF THE CHEMICAL KINETIC MECHANISMS AND TRANSPORT SUB-MODELS USED IN THE SIMULATION OF AEROTHERMOCHEMICAL PHENOMENA AND CONSEQUENTLY IDENTIFY POSSIBLE MODIFICATIONS; AND (II) TO CHARACTERIZE AND GAIN PREDICTIVE CAPABILITY ON SPHERICAL DIFFUSION FLAMES. EXPERIMENTATION IN EXTENDED MICROGRAVITY IS ESSENTIAL TO ESTABLISH AND MAINTAIN SPHERICAL FLAMES FOR RIGOROUS INVESTIGATION. THEREFORE EXPERIMENTS WILL BE CONDUCTED UTILIZING THE INTERNATIONAL-SPACE-STATION-BASED ADVANCED COMBUSTION VIA MICROGRAVITY EXPERIMENTS (ACME) SETUP FOR THE S-FLAME PROJECT. THE PROPOSED EXPERIMENTS COMPRISE TWO PARTS: (A) MAPPING AND CHARACTERIZING THE DYNAMICS OF SPHERICAL DIFFUSION FLAMES UPON IGNITION FROM NON-STEADY-STATE CONDITIONS AND THE EXTINCTION BOUNDARIES DUE TO DIRECT FINITERATE CHEMISTRY AND INDIRECT RADIATIVE HEAT LOSS; AND (B) STUDYING THE RESPONSE OF CHARACTERISTICALLY SOOTY FLAMES TO A NON-STEADY-STATE INITIAL CONDITION WITH RESPECT TO THE ASPECTS OF PART (A). THESE STUDIES HAVE IMPORTANT CONSEQUENCES FOR ENERGY CONVERSION POLLUTANT FORMATION FIRE SAFETY AND GREEN-HOUSE GAS EMISSION. THE CURRENT STAGE OF THE PROGRAM CONSISTS OF INVESTIGATIONS TO REFINE EXPERIMENTAL PARAMETERS AND TO TEST/VALIDATE DIAGNOSTICS THAT WILL BE EMPLOYED IN THE ISS-BASED EXPERIMENTS. AS SUCH GROUND-BASED EXPERIMENTS COMPUTATIONAL SIMULATION AND THEORETICAL ANALYSES WILL BE USED TO ASSESS VARIOUS ISSUES LEADING UP TO ISS-BASED EXPERIMENTATION.