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Computational Fluid Dynamics (CFD) Simulations of Jet Mixing in Tanks of Different Scales

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Computational Fluid Dynamics (CFD) Simulations of Jet Mixing in Tanks of Different Scales NASA/TM—2010-216749 Computational Fluid Dynamics (CFD) Simulations of Jet Mixing in Tanks of Different Scales Kevin Breisacher and Jeffrey Moder Glenn Research Center, Cleveland, Ohio July 2010 NASA STI Program . in Profi le Since its founding, NASA has been dedicated to the • CONFERENCE PUBLICATION. Collected advancement of aeronautics and space science. The papers from scientifi c and technical NASA Scientifi c and Technical Information (STI) conferences, symposia, seminars, or other program plays a key part in helping NASA maintain meetings sponsored or cosponsored by NASA. this important role. • SPECIAL PUBLICATION. Scientifi c, The NASA STI Program operates under the auspices technical, or historical information from of the Agency Chief Information Offi cer. It collects, NASA programs, projects, and missions, often organizes, provides for archiving, and disseminates concerned with subjects having substantial NASA’s STI. The NASA STI program provides access public interest. to the NASA Aeronautics and Space Database and its public interface, the NASA Technical Reports • TECHNICAL TRANSLATION. English- Server, thus providing one of the largest collections language translations of foreign scientifi c and of aeronautical and space science STI in the world. technical material pertinent to NASA’s mission. Results are published in both non-NASA channels and by NASA in the NASA STI Report Series, which Specialized services also include creating custom includes the following report types: thesauri, building customized databases, organizing and publishing research results. • TECHNICAL PUBLICATION. Reports of completed research or a major signifi cant phase For more information about the NASA STI of research that present the results of NASA program, see the following: programs and include extensive data or theoretical analysis. Includes compilations of signifi cant • Access the NASA STI program home page at scientifi c and technical data and information http://www.sti.nasa.gov deemed to be of continuing reference value. NASA counterpart of peer-reviewed formal • E-mail your question via the Internet to help@ professional papers but has less stringent sti.nasa.gov limitations on manuscript length and extent of graphic presentations. • Fax your question to the NASA STI Help Desk at 443–757–5803 • TECHNICAL MEMORANDUM. Scientifi c and technical fi ndings that are preliminary or • Telephone the NASA STI Help Desk at of specialized interest, e.g., quick release 443–757–5802 reports, working papers, and bibliographies that contain minimal annotation. Does not contain • Write to: extensive analysis. NASA Center for AeroSpace Information (CASI) 7115 Standard Drive • CONTRACTOR REPORT. Scientifi c and Hanover, MD 21076–1320 technical fi ndings by NASA-sponsored contractors and grantees. NASA/TM—2010-216749 Computational Fluid Dynamics (CFD) Simulations of Jet Mixing in Tanks of Different Scales Kevin Breisacher and Jeffrey Moder Glenn Research Center, Cleveland, Ohio Prepared for the 57th Joint Army-Navy-NASA-Air Force (JANNAF) Propulsion Meeting sponsored by the JANNAF Interagency Propulsion Committee Colorado Springs, Colorado, May 3–7, 2010 National Aeronautics and Space Administration Glenn Research Center Cleveland, Ohio 44135 July 2010 Acknowledgments This work was supported by the Cryogenic Fluid Management project within NASA’s Exploration Technology Development Program. This report is a formal draft or working paper, intended to solicit comments and ideas from a technical peer group. This report contains preliminary fi ndings, subject to revision as analysis proceeds. Trade names and trademarks are used in this report for identifi cation only. Their usage does not constitute an offi cial endorsement, either expressed or implied, by the National Aeronautics and Space Administration. Level of Review: This material has been technically reviewed by technical management. Available from NASA Center for Aerospace Information National Technical Information Service 7115 Standard Drive 5301 Shawnee Road Hanover, MD 21076–1320 Alexandria, VA 22312 Available electronically at http://gltrs.grc.nasa.gov Computational Fluid Dynamics (CFD) Simulations of Jet Mixing in Tanks of Different Scales Kevin Breisacher and Jeffrey Moder National Aeronautics and Space Administration Glenn Research Center Cleveland, Ohio 44135 Abstract For long-duration in-space storage of cryogenic propellants, an axial jet mixer is one concept for controlling tank pressure and reducing thermal stratification. Extensive ground-test data from the 1960s to the present exist for tank diameters of 10 ft or less. The design of axial jet mixers for tanks on the order of 30 ft diameter, such as those planned for the Ares V Earth Departure Stage (EDS) LH2 tank, will require scaling of available experimental data from much smaller tanks, as well designing for microgravity effects. This study will assess the ability for Computational Fluid Dynamics (CFD) to handle a change of scale of this magnitude by performing simulations of existing ground-based axial jet mixing experiments at two tank sizes differing by a factor of ten. Simulations of several axial jet configurations for an Ares V scale EDS LH2 tank during low Earth orbit (LEO) coast are evaluated and selected results are also presented. Data from jet mixing experiments performed in the 1960s by General Dynamics with water at two tank sizes (1 and 10 ft diameter) are used to evaluate CFD accuracy. Jet nozzle diameters ranged from 0.032 to 0.25 in. for the 1 ft diameter tank experiments and from 0.625 to 0.875 in. for the 10 ft diameter tank experiments. Thermally stratified layers were created in both tanks prior to turning on the jet mixer. Jet mixer efficiency was determined by monitoring the temperatures on thermocouple rakes in the tanks to time when the stratified layer was mixed out. Dye was frequently injected into the stratified tank and its penetration recorded. There were no velocities or turbulence quantities available in the experimental data. A commercially available, time accurate, multi-dimensional CFD code with free surface tracking (FLOW-3D from Flow Science, Inc.) is used for the simulations presented. Comparisons are made between computed temperatures at various axial locations in the tank at different times and those observed experimentally. The affect of various modeling parameters on the agreement obtained are assessed. Introduction As part of the Constellation program, the Ares V is the heavy lift launcher designed to send astronauts back to the Moon. A part of the Ares V stack, the Earth Departure Stage (EDS) is needed to escape Earth’s gravity and send the crew vehicle and lunar lander on their journey to the Moon. Due to the mass of these vehicles and the energy required to send them to the Moon, the liquid hydrogen (LH2) and liquid oxygen (LO2) propellant tanks on the EDS would be very large (~10 m diameter). Due to environmental heat leaks into the tank, a thermodynamic vent system (TVS) including a mixing device is likely to be required for in-space storage durations on the order of several days to maintain tank pressure within design limits and maintain liquid temperatures within the limits required for engine start. One such mixing device is an axial jet centered along the tank axis (with respect to net acceleration) near the tank bottom, such as shown in Figures 1 and 2. Axial jet mixers and their incorporation into a TVS have been studied (Refs. 1 to 5) since the mid-1960s and there exists extensive axial jet ground test data (using non- cyrogenic (Refs. 1 to 9) and cryogenic (Refs. 10 to 16) fluids), some drop tower test data using ethanol by Aydelott (Refs. 17 and 18), and two flight tests (Refs. 19 and 20) using Freon 113 on Shuttle (STS-43 and STS-52). Existing ground test data for axial jets using cryogenic propellants are limited to tank diameters of 3 m (10 ft) or less. There is currently no drop tower, aircraft or space flight test data available (to the authors’ knowledge) involving axial jets in closed tanks using subcritical cryogenic propellants. NASA/TM—2010-216749 1 An axial jet is one candidate for the mixing device operating in the EDS LH2 tank during several days of low Earth orbit (LEO) coast. Since experimental data for axial jets operating in cryogenic storage tanks at proposed EDS tank scales does not exist, initial design of an axial jet TVS for EDS tanks will need to rely on correlations and CFD analysis anchored against existing data. This study reports current progress in evaluating CFD accuracy for predicting axial jet thermal destratification performance at two tank scales differing by an order of magnitude. CFD simulations are compared with ground-test axial jet data (Refs. 1 to 4) using water as the working fluid. The CFD code chosen for this evaluation is the commercially available code FLOW-3D from Flow Science (Ref. 21), which has been used in previous analysis of cryogenic storage tanks and axial jets (Refs. 22 to 24). Preliminary axial jet simulations for a representative EDS LH2 tank in LEO are also performed for several axial jet configurations. The thermal destratification performance of these axial jet configurations are evaluated and selected results are presented. These preliminary axial jet EDS simulations are evaluating only the mixer performance for relatively short durations. More detailed simulations including tank heat leak, phase change, and typical self-pressurization (jet off)/pressure decay (jet on) cycles may be pursued in future work. Nomenclature a net
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