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  • 1
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    Parallel Computation of Sensitivity Derivatives with Application to Aerodynamic Optimization of a Wing (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This paper focuses on the parallel computation of aerodynamic derivatives via automatic differentiation of the Euler/Navier-Stokes solver CFL3D. The comparison with derivatives obtained by finite differences is presented and the scaling of the time required to obtain the derivatives relative to the number of processors employed for the computation is shown. Finally, the derivative computations are coupled with an optimizer and surface/volume grid deformation tools to perform an optimization to reduce the drag of a three-dimensional wing.
    Keywords: Aerodynamics
    Type: HPCCP/CAS Workshop Proceedings 1998; 219-224; NASA/CP-1999-208757
    Format: text
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  • 2
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    Aeroelastic Deflection of NURBS Geometry (1998)
    In:  CASI
    Details
    Publication Date: 2019-07-27
    Description: The purpose of this paper is to present an algorithm for using NonUniform Rational B-Spline (NURBS) representation in an aeroelastic loop. The algorithm is based on creating a least-squares NURBS surface representing the aeroelastic defection. The resulting NURBS surfaces are used to update either the original Computer- Aided Design (CAD) model, Computational Structural Mechanics (CSM) grid or the Computational Fluid Dynamics (CFD) grid. Results are presented for a generic High-Speed Civil Transport (HSCT).
    Keywords: Aerodynamics
    Type: 6th International Conference on Numerical Grid Generation in Computational Field Simulation; 6-9 Jul. Jul. 1998; London; United Kingdom
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  • 3
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    The Development of a Tool for Semi-Automated Generation of Structured and Unstructured Grids about Isolated Rotorcraft Blades (1997)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The grid generation used to model rotorcraft configurations for Computational Fluid Dynamics (CFD) analysis is highly complicated and time consuming. The highly complex geometry and irregular shapes encountered in entire rotorcraft configurations are typically modeled using overset grids. Another promising approach is to utilize unstructured grid methods. With either approach the majority of time is spent manually setting up the topology. For less complicated geometries such as isolated rotor blades, less time is obviously required. This paper discusses the capabilities of a tool called Rotor blade Optimized Topology Organizer and Renderer(ROTOR) being developed to quickly generate block structured grids and unstructured tetrahedral grids about isolated blades. The key algorithm uses individual airfoil sections to construct a Non-Uniform Rational B-Spline(NURBS) surface representation of the rotor blade. This continuous surface definition can be queried to define the block topology used in constructing a structured mesh around the rotor blade. Alternatively, the surface definition can be used to define the surface patches and grid cell spacing requirements for generating unstructured surface and volume grids. Presently, the primary output for ROTOR is block structured grids using 0-H and H-H topologies suitable for full-potential solvers. This paper will discuss the present capabilities of the tool and highlight future work.
    Keywords: Aerodynamics
    Type: NASA/TM-97-206146 , NAS 1.15:206146 , Technical Specialists'' Meeting for Rotorcraft Acoustics and Aerodynamics; Oct 28, 1997 - Oct 30, 1997; Williamsburg, VA; United States
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  • 4
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    Multidisciplinary Aerodynamic-Structural Shape Optimization Using Deformation (MASSOUD) (2000)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: This paper presents a multidisciplinary shape parameterization approach. The approach consists of two basic concepts: (1) parameterizing the shape perturbations rather than the geometry itself and (2) performing the shape deformation by means of the soft object animation algorithms used in computer graphics. Because the formulation presented in this paper is independent of grid topology, we can treat computational fluid dynamics and finite element grids in a similar manner. The proposed approach is simple, compact, and efficient. Also, the analytical sensitivity derivatives are easily computed for use in a gradient-based optimization. This algorithm is suitable for low-fidelity (e.g., linear aerodynamics and equivalent laminated plate structures) and high-fidelity (e.g., nonlinear computational fluid dynamics and detailed finite element modeling analysis tools. This paper contains the implementation details of parameterizing for planform, twist, dihedral, thickness, camber, and free-form surface. Results are presented for a multidisciplinary design optimization application consisting of nonlinear computational fluid dynamics, detailed computational structural mechanics, and a simple performance module.
    Keywords: Aerodynamics
    Type: Multidisciplinary Analysis and Optimization; Sep 06, 2000 - Sep 08, 2000; Long Beach, CA; United States
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  • 5
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    Parametric Mass Modeling for Mars Entry, Descent and Landing System Analysis Study (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper provides an overview of the parametric mass models used for the Entry, Descent, and Landing Systems Analysis study conducted by NASA in FY2009-2010. The study examined eight unique exploration class architectures that included elements such as a rigid mid-L/D aeroshell, a lifting hypersonic inflatable decelerator, a drag supersonic inflatable decelerator, a lifting supersonic inflatable decelerator implemented with a skirt, and subsonic/supersonic retro-propulsion. Parametric models used in this study relate the component mass to vehicle dimensions and mission key environmental parameters such as maximum deceleration and total heat load. The use of a parametric mass model allows the simultaneous optimization of trajectory and mass sizing parameters.
    Keywords: Aerodynamics
    Type: AIAA Paper 2011-1038 , NF1676L-11883 , 49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition; Jan 04, 2011 - Jan 07, 2011; Orlando, FL; United States
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  • 6
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    Enhancements to TetrUSS for NASA Constellation Program (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The NASA Constellation program is utilizing Computational Fluid Dynamics (CFD) predictions for generating aerodynamic databases and design loads for the Ares I, Ares I-X, and Ares V launch vehicles and for aerodynamic databases for the Orion crew exploration vehicle and its launch abort system configuration. This effort presents several challenges to applied aerodynamicists due to complex geometries and flow physics, as well as from the juxtaposition of short schedule program requirements with high fidelity CFD simulations. NASA TetrUSS codes (GridTool/VGRID/USM3D) have been making extensive contributions in this effort. This paper will provide an overview of several enhancements made to the various elements of TetrUSS suite of codes. Representative TetrUSS solutions for selected Constellation program elements will be shown. Best practices guidelines and scripting developed for generating TetrUSS solutions in a production environment will also be described.
    Keywords: Aerodynamics
    Type: AIAA Paper 2011-1111 , NF1676L-10793 , 49th AIAA Aerospace Sciences Meeting; Jan 04, 2011 - Jan 07, 2011; Orlando, FL; United States
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