Computation Of Flow About A Pitching Wing/Fuselage
Report presents computational study of unsteady transonic flow about airplanelike body as body pitches upward in increasing angle of attack.
Obayashi, S.↗
Engineering topics
Obayashi, S.
Publications and source records attributed to Obayashi, S..
Computed Flow About The Integrated Space Shuttle, Revisited
Report discusses numerical simulations of flow of air about integrated space shuttle (complete space shuttle assembly including orbiter, solid rocket boosters, and external tank) in ascent. Updated version of report described in "Computed Flow About The Integrated Space Shuttle" (ARC-12685). Goal of studies to improve understanding of, and ability to predict how integrated space shuttle performs during both nominal and aborted ascent under various conditions.
Buning, P. G.↗
Convergence acceleration of an aeroelastic Navier-Stokes solver
New capabilities have been added to a Navier-Stokes solver to perform steady-state simulations more efficiently. The flow solver for solving the Navier-Stokes equations is completely rewritten with a combination of the LU-SGS (Lower-Upper factored Symmetric Gauss-Seidel) implicit method and the modified HLLE (Harten-Lax-van Leer-Einfeldt) upwind scheme. A pseudo-time marching method is used for the directly coupled structural equations to improve overall convergence rates for static aeroelastic analysis. Results are demonstrated for transonic flows over rigid and flexible wings.
Obayashi, S.↗
Virtual zone Navier-Stokes computations for oscillating control surfaces
A new zoning method called 'virtual zones' has been developed for application to an unsteady finite difference Navier-Stokes code. The virtual zoning method simplifies the zoning and gridding of complex configurations for use with patched multi-zone flow codes. An existing interpolation method has been extensively modified to bring the run time for the interpolation procedure down to the same level as for the flow solver. Unsteady Navier-Stokes computations have been performed for transonic flow over a clipped delta wing with an oscillating control surface. The computed unsteady pressure and response characteristics of the control-surface motion compare well with experimental data.
Klopfer, G. H.↗
Flowfield of a lifting rotor in hover - A Navier-Stokes simulation
The viscous, three-dimensional flowfield of a lifting helicopter rotor in hover is calculated by using an upwind, implicit, finite-difference numerical method for solving the thin layer Navier-Stokes equations. The induced effects of the wake, including the interaction of tip vortices with successive blades, are calculated as part off the overall flowfield solution without using any ad hoc wake models. Comparison of the numerical results for the subsonic and transonic conditions show good agreement with the experimental data and with the previously published Navier-Stokes calculations using a simple wake model. Some comparisons with Euler calculations are also presented, along with some discussions of the grid refinement studies.
Srinivasan, G. R.↗
Algorithm development with applications to aerodynamics and aeroelasticity
The development of a streamwise upwind algorithm is presented. Applications of this algorithm to steady flow over a delta wing and unsteady flow over an oscillating wing, respectively, are covered. An extension to higher order accuracy for upwind methods is discussed. This scheme will use the compatibility relations for the extension. The use of multiple zones in the calculation of unsteady flows is considered. Multiple zones are one way to treat complex configurations, such as complete aircraft. Aeroelastic calculations are discussed. A procedure for aeroelastic calculations is described that simultaneously solves the aerodynamic and structural equations of motion. Sample calculations are given to illustrate the above.
Goorjian, P. M.↗
Computed Flow About The Integrated Space Shuttle
Report discusses numerical simulations of flow of air about integrated Space Shuttle in ascent. Goal: to improve understanding of, and ability to predict, how integrated Space Shuttle will perform during both nominal and aborted ascent under various conditions. These and other numerical simulations intended both to supplement wind-tunnel data, corrupted to some extent by scaling and wall-interference effects, and to compensate for scarcity of valid flight data.
Buning, P. G.↗
Navier-Stokes Simulation Of Wind-Tunnel Flow
Report describes three-dimensional Navier-Stokes simulation of transonic flow past model wing in wind tunnel and in free air. Numerical integration performed by LU-ADI factorization algorithm. Simulation shows effects of walls of tunnel.
Obayashi, S.↗
Numerical solutions of forward-flight rotor flow using an upwind method
Explore the source record for details and available documents.
Chen, C. L.↗
Flowfield of a lifting hovering rotor: A Navier-Stokes simulation
The viscous, three-dimensional flowfield of a lifting helicopter rotor in hover is calculated by using an upwind, implicit, finite-difference numerical method for solving the thin layer Navier-Stokes equations. The induced effects of the wake, including the interaction of tip vortices with successive blades, are calculated as a part of the overall flowfield solution without using any ad hoc wake models. Comparison of the numerical results for the subsonic and transonic conditions show good agreement with the experimental data and with the previously published Navier-Stokes calculations using a simple wake model. Some comparisons with Euler calculations are also presented, along with some discussions of the grid refinement studies.
Srinivasan, G. R.↗
Numerical solutions of forward-flight rotor flow using an upwind method
A finite-volume upwind algorithm for solving the 3-D Euler equations with a moving grid has been developed for computing helicopter forward-flight rotor flows. The computed pressure distributions and shock positions of high-speed rotor flow are compared with various experimental data as well as with other numerical results, and the agreement is encouraging. A comparison of quasi-steady solutions with unsteady solutions reveals that when a shock occurs in the flowfield, the assumption of quasi-steady flow may fail due to the time-lag of the shock motion. Similarly, three-dimensional effects cannot be neglected. Sufficient subiterations for each time step are required to avoid numerical lag effects in using the present method. The redistribution of the residual due to the coordinate transformation is discussed. For high-order MUSCL-type schemes, a coordinate-independent solution can be obtained by interpolating primitive variables.
Chen, C. L.↗
Numerical simulation of the integrated space shuttle vehicle in ascent
A simulation of the flow about the integrated space shuttle vehicle in ascent mode has been undertaken for various flight conditions using the Chimera composite grid discretization approach. Overset body-conforming grids were used to represent each geometric component, and an implicit approximately factored finite-difference procedure was used to solve the three-dimensional thin-layer Navier-Stokes equations. The computational results have been compared with both wind tunnel and flight test data. Although relatively good agreement is obtained with the experimental data, further refinement and evaluation of numerical error is under way.
Buning, P. G.↗