The innovative methodologies proposed in this STTR Phase 2 project will enhance Loci-STREAM which is a high performance, high fidelity simulation tool already being used at NASA/MSFC for a variety of CFD applications. This project will address critical needs in order to enable fast and accurate simulations of liquid space propulsion systems of relevance to NASA's Space Launch System (SLS) program (LOX/RP-1 engines such as F-1 or potential replacement of RD-180, and LOX/LH2 engines such as RS-25, RS-25D/E, RL10, J-2X). The key methodologies which will be integrated into a production version of the Loci-STREAM code are the following: (a) Primary atomization modeling using Level Set methodology to model the liquid (core) jet, (b) Lagrangian particle tracking (LPT) for the droplets resulting from primary atomization, (c) Evaporation models for the droplets, (d) Flamelet models for turbulent combustion, (e) Adaptive tabulation for flamelet models, and (f) Hybrid RANS-LES (HRLES) methodology. Integration of the above methodologies into Loci-STREAM will result in a state-of-the-art multiphase combustion modeling tool which will enable fast and accurate design and analysis of liquid rocket engine flow environments, combustion stability analysis, etc. which constitute critical components of space propulsion engines that are part of NASA's SLS.