the current study presents the results of the aerodynamic noise prediction of the flow field around a naca 0012 airfoil at a chord-based reynolds number of 100,000 and at 8.4 degree angle of attack. an incompressible large eddy simulation (les) turbulence model is applied to obtain the instantaneous turbulent flow field. the noise prediction is performed by the ffowcs williams and hawkings (fw-...

Improving aerodynamic models for adverse loss-of-control conditions in flight is an area being researched under the NASA Aviation Safety Program. Aerodynamic models appropriate for loss of control conditions require a more general mathematical representation to predict nonlinear unsteady behaviors. As more general aerodynamic models are studied that include nonlinear higher order effects, the p...

This paper discusses the influence of aerodynamic drag torque on the dynamics of a satellite in a very low altitude orbit. The larger atmospheric density in low altitude earth orbits results in significant aerodynamic drag torques acting on the satellite. With a conventional satellite design this may result in instability. This paper shows how the instability can be avoided, and how the aerodyn...

[1] The aerodynamic friction between air and sea is an important part of the momentum balance in the development of tropical cyclones. Measurements of the drag coefficient, relating the tangential stress (frictional drag) between wind and water to the wind speed and air density, have yielded reliable information in wind speeds less than 20 m/s (about 39 knots). In these moderate conditions it i...

This paper focuses on the demonstration of an integrated aero-structural method for the design of aerospace vehicles. Both aerodynamics and structures are represented using high-fidelity models such as the Euler equations for the aerodynamics and a detailed finite element model for the primary structure. The aerodynamic outer mold line (OML) and a structure of fixed topology are parameterized u...

NASA’s Hyper-X Research Vehicle will provide a unique opportunity to obtain data on an operational airframe integrated scramjet propulsion system at true flight conditions. The airframe integrated nature of the scramjet engine with the Hyper-X vehicle results in a strong coupling effect between the propulsion system operation and the airframe’s basic aerodynamic characteristics. Comments on gen...

The development and application of model reduction techniques have been widely investigated for problems in unsteady aerodynamic systems, driven mainly by the need to develop effective economical computational models capturing as much flow physics as possible. These techniques which have been based on a number of approaches such as balanced truncation, Arnoldi, proper orthogonal decomposition e...

Aerodynamic flows involve features with a wide range of spatial and temporal scales which need to be resolved in order to accurately predict desired engineering quantities. While computational fluid dynamics (CFD) has advanced considerably in the past 30 years, the desire to perform more complex, higher-fidelity simulations remains. Present day CFD simulations are limited by the lack of an effi...

Production of a trill depends on several articulatory and aerodynamic constraints. These constraints can be held responsible for various sound changes in Slavic languages which all involve depalatalization or frication of ProtoSlavic palatalized trilled r. As soon as a trill is affected by palatalization, the aerodynamic conditions are changed and the possibility of trill production lowers. Sma...

We investigate the use of simple aerodynamic models for the feedback control of underactuated aerial vehicles flying with large flight envelopes. Thrust-propelled vehicles with a body shape symmetric with respect to the thrust axis are considered. Upon a condition on the aerodynamic characteristics of the vehicle, we show that the equilibrium orientation can be explicitly determined as a functi...