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  • 1
    Publication Date: 2019-07-20
    Keywords: Launch Vehicles and Launch Operations
    Type: ARC-E-DAA-TN64631 , AIAA SciTech Forum 2019; Jan 07, 2019 - Jan 11, 2019; San Diego, CA; United States
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  • 2
    Publication Date: 2019-07-20
    Description: This paper presents details of Computational Fluid Dynamic modeling of the Space Launch System during ascent. The primary focus of the paper is the flow simulation of the vehicle during ascent using the Overflow Navier-Stokes code. Computations of 739 first-stage flight conditions covering a range of Mach numbers, angles of attack, and roll angles were computed. The overset grid system contained 375 million grid points, and over 28 mil- lion CPU hours were used in the simulations. The simulations were run on the Pleiades supercomputer at the NASA Advanced Supercomputer Center at Ames Research Center. The data products from this work include integrated line-loads, surface pressure coefficients, venting pressures, and protuberance air-loads. Detailed comparisons were made of the aerodynamic performance predicted by Overflow and the wind-tunnel derived aero- dynamic database. A small number of the cases were run with two different turbulence models and with two differencing schemes. These results were used to quantify the sensitivity to the choice of the turbulence model and to the differencing scheme. The paper also introduces an effort to use the inviscid, unstructured Cartesian solver Cart3D to compute the aerodynamics during booster separation. Adaptive mesh refinement is being used to enable accurate simulations of sixteen booster-separation-motor plumes. The use of this tool is explored in preparation for building a booster-separation aerodynamic database.
    Keywords: Aerodynamics; Computer Programming and Software
    Type: ARC-E-DAA-TN19559 , AIAA Science and Technology Forum and Exposition (AIAA SciTech 2015); Jan 05, 2015 - Jan 09, 2015; Kissimmee, FL; United States
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  • 3
    Publication Date: 2019-07-20
    Description: No abstract available
    Keywords: Computer Programming and Software; Aeronautics (General)
    Type: ARC-E-DAA-TN63281 , International Conference for High Performance Computing, Networking, Storage, and Analysis (SC18); Nov 11, 2018 - Nov 16, 2018; Dallas, TX; United States
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  • 4
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Spacecraft Design, Testing and Performance; Spacecraft Propulsion and Power
    Type: Annual AIAA/USU Conference on Small Satellites; Aug 08, 2015 - Aug 13, 2015; Logan, UT; United States
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  • 5
    Publication Date: 2019-07-13
    Description: This paper investigates the feasibility of Earth-transfer and interplanetary mission architectures for miniaturized spacecraft using emerging small solar electric propulsion technologies. Emerging small SEP thrusters offer significant advantages relative to existing technologies and will enable U-class systems to perform trajectory maneuvers with significant Delta V requirements. The approach in this paper is unique because it integrates trajectory design with vehicle sizing and accounts for the system and operational constraints of small U-class missions. The modeling framework includes integrated propulsion, orbit, energy, and external environment dynamics and systems-level power, energy, mass, and volume constraints. The trajectory simulation environment models orbit boosts in Earth orbit and flyby and capture trajectories to interplanetary destinations. A family of small spacecraft mission architectures are studied, including altitude and inclination transfers in Earth orbit and trajectories that escape Earth orbit and travel to interplanetary destinations such as Mercury, Venus, and Mars. Results are presented visually to show the trade-offs between competing performance objectives such as maximizing available mass and volume for payloads and minimizing transfer time. The results demonstrate the feasibility of using small spacecraft to perform significant Earth and interplanetary orbit transfers in less than one year with reasonable U-class mass, power, volume, and mission durations.
    Keywords: Spacecraft Design, Testing and Performance
    Type: SSC15-IV-6 , Annual AIAA/USU Conference on Small Satellites; Aug 08, 2015 - Aug 13, 2015; Logan, UT; United States
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  • 6
    Publication Date: 2019-07-13
    Description: The Interplanetary Small Satellite Conference will be held at San Jose State University on May 1 and 2, 2017. The program attached here contains logistical information for attendees, the agenda, and abstracts of the conference presentations. All abstracts were reviewed by their authors' home institute and approved for public release prior to inclusion in the program booklet. The ISSC explores mission concepts, emerging technologies, and fosters outside the box thinking critical to future interplanetary small satellite missions.
    Keywords: Engineering (General)
    Type: ARC-E-DAA-TN42044 , Interplanetary Small Satellite Conference; May 01, 2017 - May 02, 2017; San Jose, CA; United States
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  • 7
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Launch Vehicles and Launch Operations; Fluid Mechanics and Thermodynamics
    Type: ARC-E-DAA-TN49673 , AIAA Aviation Forum; Jun 25, 2018 - Jun 29, 2018; Atlanta, GA; United States
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  • 8
    Publication Date: 2019-07-13
    Description: This paper presents a method for adjusting sectional loads to match target values for integrated force and moment coefficients. In a typical application, the sectional load profile for one flight condition is calculated from Computational Fluid Dynamics (CFD) while the integrated forces and moments are measured in a wind tunnel experiment. These two methods do not generally result in identical predictions, and this leads to an inherent inconsistency between different data products. This paper aims to provide a procedure to remove that inconsistency. A sectional load profile for a launch vehicle splits the rocket into slices along its length and calculates the aerodynamic loading on each slice, which leads to a one-dimensional aerodynamic load profile that is used for structural analysis. Adjusting sectional loads, also known as line loads, is a nontrivial matter due to several consistency constraints. For example, the adjusted sectional normal force profile must be consistent with both the integrated normal force and pitching moment. To avoid such inconsistency issues, this paper presents a method using a Proper Orthogonal Decomposition (POD) to generate basis functions to adjust the sectional load profiles. As a corollary, this correction method enables the creation of an uncertainty quantification for sectional loads that is consistent with the dispersed integrated force and moment database and its uncertainty quantification. Several extensions to this technique, such as applying the method to the surface pressures, are considered.
    Keywords: Launch Vehicles and Launch Operations; Fluid Mechanics and Thermodynamics
    Type: ARC-E-DAA-TN57593 , AIAA Aviation Forum; Apr 25, 2018 - Apr 29, 2018; Atlanta, GA; United States
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  • 9
    Publication Date: 2019-10-12
    Description: NASA's new Space Launch System (SLS) will be the first rocket since the Saturn V (1967-1973) to carry astronauts beyond low earth orbit-and will carry 10% more payload than Saturn V and three times the payload of the space shuttle. The SLS configuration consists of a center core and two solid rocket boosters that separate from the core as their fuel is exhausted two minutes after lift-off. During these first two minutes of flight, the vehicle powers its way through strong shock waves as it accelerates past the speed of sound, then pushes beyond strong aerodynamic loads at the maximum dynamic pressure, and is ultimately enveloped by gaseous plumes from the booster-separation motors. The SLS program relies on computational fluid dynamic (CFD) simulations to provide much of the data needed to build aerodynamic databases describing the structural load distribution, surface pressures, and aerodynamic forces on the vehicle.
    Keywords: Aerodynamics; Launch Vehicles and Launch Operations
    Type: ARC-E-DAA-TN48979 , Supercomputing 2017; Nov 12, 2017 - Nov 16, 2017; Denver, CO; United States
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  • 10
    Publication Date: 2019-07-13
    Description: This paper presents details of Computational Fluid Dynamic (CFD) simulations of the Space Launch System during solid-rocket booster separation using the Cart3D inviscid code with comparisons to Overflow viscous CFD results and a wind tunnel test performed at NASA Langley Research Center's Unitary PlanWind Tunnel. The Space Launch System (SLS) launch vehicle includes two solid-rocket boosters that burn out before the primary core stage and thus must be discarded during the ascent trajectory. The main challenges for creating an aerodynamic database for this separation event are the large number of basis variables (including orientation of the core, relative position and orientation of the boosters, and rocket thrust levels) and the complex flow caused by the booster separation motors. The solid-rocket boosters are modified from their form when used with the Space Shuttle Launch Vehicle, which has a rich flight history. However, the differences between the SLS core and the Space Shuttle External Tank result in the boosters separating with much narrower clearances, and so reducing aerodynamic uncertainty is necessary to clear the integrated system for flight. This paper discusses an approach that has been developed to analyze about 6000 wind tunnel simulations and 5000 flight vehicle simulations using Cart3D in adaptive-meshing mode. In addition, a discussion is presented of Overflow viscous CFD runs used for uncertainty quantification. Finally, the article presents lessons learned and improvements that will be implemented in future separation databases.
    Keywords: Aerodynamics
    Type: ARC-E-DAA-TN24267 , AIAA Aviation 2015, Applied Aerodynamics Conference; Jun 22, 2015 - Jun 26, 2015; Dallas, TX; United States
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