Description: This project is geared towards a computationally efficient, robust computational fluid dynamics (CFD) tool for simulating unsteady multiphase flows of critical importance to NASA in their ground and launch systems processing technologies. The key features of the proposed work are: (a) Significant cost reduction in unsteady simulations via the PIMPLE algorithm, and (b) a fast and robust Algebraic Volume of Fluid (AVOF) method for two-phase flows. This methodology will be developed in the Loci-STREAM CFD code and will allow significantly reduced solution time for unsteady simulations of cavitating flows and fluid-structure interaction (FSI) simulations at NASA, as well as simulation of liquid jets and sprays such as in NASA/SSC’s B-2 test facility. The work will involve: (a) upgrading the unsteady methodology in Loci-STREAM by implementing the PIMPLE algorithm, and will improve runtime of cavitation and FSI simulations by a factor of 3–5, and (b) Implementing an algebraic VOF method using compressive schemes which will allow simulations of two-phase flows (involving liquid jets) in a robust and more efficient manner (significantly faster solution times) manner than is currently possible with the geometric VOF available in Loci-STREAM. Two types of compressive schemes will be implemented: (a) Schemes based on the Normalized Variable Diagram (NVD) and Convection Boundedness Criterion (CBC), and (b) Flux-limiting schemes with the total variation diminishing (TVD) condition. The following application areas will benefit immediately from this project: (i) Unsteady cavitation in cryogenic propellant tanks, valve flows, and run lines, (ii) Transient fluid structure interaction (FSI) between cryogenic fluids and immersed components to predict the dynamic loads, frequency response of facilities, and (c) Modeling of liquid (water) jets including their breakup for flow tests on the B-2 test stand to verify the water system capability and functionality in support of the SLS.

Benefits: Modeling of cavitation in cryogenic propellant tanks, valve flows, and run lines Modeling of transient fluid structure interaction (FSI) between cryogenic fluids and immersed components to predict the dynamic loads, frequency response of facilities Modeling of water jets for flow tests on the B-2 test stand to verify the water system capability and functionality in support of the SLS Water deluge mitigation for rocket launch induced environments Subcritical injector analysis for gas generators, preburners and thrust chambers

Two-phase applications involving non-reacting & reacting flows. Fast and accurate simulation for reacting flows at companies dealing with space propulsion, gas turbine, diesel engines, etc. Loci-STREAM code is being used at Aerojet Rocketdyne for gas-gas injector simulations; it’s applicability will be broadened to liquid propellant engines by this project.