Linear unsteady aerodynamic models are obtained for a NACA 0006 airfoil in a wind tunnel experiment at Reynolds number 65,000. A family of system identification maneuvers, based on a canonical step-up, hold maneuver, are specifically designed to extract relevant unsteady information from phase averaged wind tunnel measurements. Linear models based on these maneuvers are constructed using OKID/E...

A new method is offered to simulate heat transfer processes in nonequilibrium viscous shock layers near the catalytic body surface at hypcrsonic wind tunnel and free natural flight conditions. The method is based on computations of nonequilibrium parameters in thin viscous sbock layers, and on an analogy with flows that arise behind normal shock waves. The obtained simplified relationships betw...

NASA Ames Research Center has developed several advanced distributed information systems to assist the distribution, analysis and management of data from experimental and numerical tests on aircraft wings and other aeronautical components. These systems provide immediate access to numerical aeronautics simulations and redefine the analysis operations for classic wind tunnel tests. The informati...

The development of Doppler global velocimetry is described from its inception to its use as a flow diagnostics tool. Its evolution is traced from an elementary one-component laboratory prototype, to a full three-component configuration operating in a wind tunnel at focal distances exceeding 15 m. As part of the developmental process, several wind tunnel flow field investigations were conducted....

Serving as one key component of the most important lifeline infrastructure system, transmission towers are vulnerable to multiple nature hazards including strong wind and could pose severe threats to the power system security with possible blackouts under extreme weather conditions, such as hurricanes, derechoes, or winter storms. For the security and resiliency of the power system, it is impor...

A new approach based on a Generalized Regression Neural Network (GRNN) has been proposed to predict the planform surface pressure field on a wing-tail combination in low subsonic flow. Extensive wind tunnel results were used for training the network and verification of the values predicted by this approach. GRNN has been trained by the aforementioned experimental data and subsequently was used ...

To clarify the behavior of the blade tip vortices of a wind turbine equipped with a brimmed-diffuser shroud, called a “Wind-Lens turbine”, we conducted a three-dimensional numerical simulation using a large eddy simulation (LES). Since this unique wind turbine consists of not only rotating blades but also a diffuser shroud with a broad-ring brim at the exit periphery, the flow field around the ...

Tendency to build more slender and more flexible tall buildings have made these structures susceptible to action of wind. Therefore, wind force is one of the prime considerations in design of tall buildings. The prediction of wind-induced pressure coefficients on the surface of the buildings is of considerable practical importance. Wind tunnel testing is one of the main methods for wind load de...