Modifications to a three-dimensional Euler aerodynamic method (TEAM) and their effect on the accuracy of transonic flow simulations are described. TEAM’S solution algorithm is based on a finite-volume spatial discret...
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A combination of the Euler and thin-layer Navier-Stokes equations were solved for the flowfield around a wingstrake- fuselage configuration similar to the General Dynamics F-16A aircraft. Steady-state solutions were o...
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A source term decomposition method is proposed, and it is shown to be computationally advantageous in highly swirling flows. The proposed method uses a corrector form of the tangential momentum equation to decompose t...
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A source term decomposition method is proposed, and it is shown to be computationally advantageous in highly swirling flows. The proposed method uses a corrector form of the tangential momentum equation to decompose the source terms of the radial momentum equation.
Six methods for design of reduced-order compensation are compared using an example problem. The methods considered comprise five linear-quadratic reduction techniques, reviewed in a recent paper by Liu and Anderson, a...
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The drag of airfoils in transonic flow may be reduced through the use of a passive venting system that uses a porous plate for part of the airfoil upper surface with a vent chamber beneath the porous plate. This arran...
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The drag of airfoils in transonic flow may be reduced through the use of a passive venting system that uses a porous plate for part of the airfoil upper surface with a vent chamber beneath the porous plate. This arrangement allows air from a high-pressure region on the airfoil surface to be vented to a low-pressure region, thereby modifying the airfoil flow field and resulting indrag reduction. Using this approach, an existing cavity model was modified to house a porous floor with a vent chamber beneath the floor. The expectation was that for closed cavity flow the high-pressure air at the rear of the cavity would vent to the low-pressure region at the front of the cavity, causing the flowfield to switch to open cavity flow. This Note describes the results of an experimental investigation to determine the effectiveness of this passive venting system.
Two methods to improve the efficiency of predicting viscous/inviscid interaction in hypersonic flow are examined using an explicit full Navier-Stokes and a parabolized Navier-Stokes procedure. For the first method, a ...
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A new stabilization method of treating constraints in multibody dynamical systems is presented. By tailoring a penalty form of the constraint equations, the method achieves stabilization without artificial damping and...
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A new stabilization method of treating constraints in multibody dynamical systems is presented. By tailoring a penalty form of the constraint equations, the method achieves stabilization without artificial damping and yields a companion matrix differential equation for the constraint forces; hence, the constraint forces are obtained by integrating the companion differential equation for the constraint forces in time. A principal feature of the method is that the errors committed in each constraint condition decay with its corresponding characteristic time scale associated with its constraint force. Numerical experiments indicate that the method yields a marked improvement over existing techniques. (Author)
A general adaptive algorithm is developed on triangular meshes. The adaptivity is provided by a combination of node addition, dynamic node connectivity and a simple node movement strategy. While the local restructurin...
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This paper describes a controller for automatic attitude maneuvers of reaction-control-jet-equipped spacecraft. It is based on a new, real-time algorithm for solution of fuel-optimal maneuvers, assuming on-off control...
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This paper describes a controller for automatic attitude maneuvers of reaction-control-jet-equipped spacecraft. It is based on a new, real-time algorithm for solution of fuel-optimal maneuvers, assuming on-off control and linearized dynamics. These solutions provide efficient model trajectories that are easily tracked using a feed-forward, feedback controller structure. This approach was developed as a software upgrade to the Space Shuttle Orbiter on-orbit autopilot, for which it shows a very substantial performance benefit in a wide range of simulated maneuver tasks.
The extension of a recently developed implicit/explicit approach to analyzing two-dimensional ducted supersonic mixing problems with finite-rate chemistry is presented. The hybrid approach combines a fully implicit pa...
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