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Anders, S. G.

Publications and source records attributed to Anders, S. G..

Aspects of Numerical Simulation of Circulation Control Airfoils

The mass-averaged compressible Navier-Stokes equations are solved for circulation control airfoils. Numerical solutions are computed with a multigrid method that uses an implicit approximate factorization smoother. The effects of flow conditions (e.g., free-stream Mach number, angle of attack, momentum coefficient) and mesh on the prediction of circulation control airfoil flows are considered. In addition, the impact of turbulence modeling, including curvature effects and modifications to reduce eddy viscosity levels in the wall jet (i.e., Coanda flow), is discussed. Computed pressure distributions are compared with available experimental data.

Swanson, R. C.

Progress Towards Computational Method for Circulation Control Airfoils

The compressible Reynolds-averaged Navier-Stokes equations are solved for circulation control airfoil flows. Numerical solutions are computed with both structured and unstructured grid solvers. Several turbulence models are considered, including the Spalart-Allmaras model with and without curvature corrections, the shear stress transport model of Menter, and the k-enstrophy model. Circulation control flows with jet momentum coefficients of 0.03, 0.10, and 0.226 are considered. Comparisons are made between computed and experimental pressure distributions, velocity profiles, Reynolds stress profiles, and streamline patterns. Including curvature effects yields the closest agreement with the measured data.

Swanson, R. C.

Snapshot of Active Flow Control Research at NASA Langley

NASA Langley is aggressively investigating the potential advantages of active flow control as opposed to more traditional aerodynamic techniques. Many of these techniques will be blended with advanced materials and structures to further enhance payoff. Therefore a multi-disciplinary approach to technology development is being attempted that includes researchers from the more historical disciplines of fluid mechanics. acoustics, material science, structural mechanics, and control theory. The overall goals of the topics presented are focused on advancing the state of knowledge and understanding of controllable fundamental mechanisms in fluids rather than on specific engineering problems. An organizational view of current research activities at NASA Langley in active flow control as supported by several programs such as the Morphing Project under Breakthrough Vehicle Technologies Program (BVT). the Ultra-Efficient Engine Technology Program (UEET), and the 21st Century Aircraft Technology Program (TCAT) is presented. On-center research as well as NASA Langley funded contracts and grants are discussed at a relatively high level. The products of this research, as part of the fundamental NASA R and D (research and development) program. will be demonstrated as either bench-top experiments, wind-tunnel investigations, or in flight tests. Later they will be transferred to more applied research programs within NASA, DOD (Department of Defense), and U.S. industry.

Washburn, A. E.

Supersonic and hypersonic quiet tunnel technology at NASA Langley

Quiet tunnel technology at NASA Langley is reviewed focusing on historical background, basic quiet tunnel concepts, design methodology, and significant results. Each of the NASA Langley quiet tunnels and recent flow quality results for a refurbished Mach 6 quiet nozzle are presented. It is concluded that high-speed quiet tunels should be viewed as a required adjunct to computational and experimental tools being developed to explore issues of instability and transition physics. The quiet tunnel technology can produce and maintain an adequately smooth nozzle finish, control settling chamber disturbances, and keep the facility clean and is capable of adequately measuring flow disturbances.

Wilkinson, S. P.

Development of a Mach 18 quiet helium tunnel for transition research

A new 'quiet' tunnel, the Mach 18 quiet helium tunnel has been developed to support research on transition estimation in hypersonic flows. An existing facility has been modified to provide low-disturbance flow for transition research in a conical nozzle with an exit Mach number of about 18. This paper describes tunnel modifications, unique features, and operating parameters. The tunnel will be used primarily for the validation of boundary-layer stability codes and includes a 1 micron flow filter, a new inlet diffuser, several flow conditioning elements, a conical nozzle, and a boundary-layer bleed system.

Anders, S. G.