The unsteady aerodynamic behavior of a bird-damaged fan stage at the inlet of a highbypass turbofan engine is examined with a computational fluid dynamics (CFD) aerodynamic model suitable for use in an aeroelastic response calculation. ANSYS CFX, a commercially available CFD solver, is utilized to perform the steady-state and unsteady CFD calculations for the undamaged and damaged fan. The dama...

The aerial environment in the operating domain of small-scale natural and artificial flapping wing fliers is highly complex, unsteady and generally turbulent. Considering flapping flight in an unsteady wind environment with a periodically varying lateral velocity component, we show that body rotations experienced by flapping wing fliers result in the reorientation of the aerodynamic force vecto...

Insect wings are deformable structures that change shape passively and dynamically owing to inertial and aerodynamic forces during flight. It is still unclear how the three-dimensional and passive change of wing kinematics owing to inherent wing flexibility contributes to unsteady aerodynamics and energetics in insect flapping flight. Here, we perform a systematic fluid-structure interaction ba...

The blades of wind turbines are the most important parts in producing power output. In this study, a section of a 660 KW wind turbine blade will be installed in Iran in near future was tested in a wind tunnel. In addition to steady tests, various unsteady tests including the effects of reduced frequency, mean angle of attack, and amplitudes were carried out. The preliminary results show strong ...

Wind-tunnel experimentswere conducted on a 47-deg sweep, scaled 1303unmanned air vehiclemodel to assess the performance of an innovative windward-surface plasma actuator design for flight control at low angles of attack. Control was implemented by altering the flow past an aft separation ramp on the windward side using a single dielectric barrier discharge plasma actuator. The influence of ramp...

Introduction: The flight of insects and birds and the swimming of fish have been sources of continuous fascination throughout the ages. Observation and controlled experimentation have historically been the main sources of information on performance. The mathematical description of the performance of flying creatures has been limited, due to the previously insurmountable difficulties associated ...

A comprehensive wind-tunnel test program on both a 65o delta an 80o/65o double delta wing model has been recently completed. The program included static and dynamic force tests. A brief description of the various experiments is presented, as well as results that demonstrate the value of the previously proposed "hypersurface" representation of aerodynamic loads in the non-linear and unsteady reg...

Most insects are thought to fly by creating a leading-edge vortex that remains attached to the wing as it translates through a stroke. In the species examined so far, stroke amplitude is large, and most of the aerodynamic force is produced halfway through a stroke when translation velocities are highest. Here we demonstrate that honeybees use an alternative strategy, hovering with relatively lo...

A basic problem in flight dynamics is the mathematical formulation of the aerodynamic model for aircraft. This study is part of an ongoing effort at NASA Langley to develop a more general formulation of the aerodynamic model for aircraft that includes nonlinear unsteady aerodynamics and to develop appropriate test techniques that facilitate identification of these models. A methodology for mode...

Several approaches for modelling the longitudinal aerodynamic coefficients of a fighter aircraft at high angles of attack, including the unsteady effects are presented. A traditional approach where the model of the coefficient arises in the form of the steady and unsteady effects, the unsteady effect being modelled by means of transfer functions. The second approach uses an internal variable de...