Nineteen modern airliner Loss of Control (LOC) accidents resulting in aerodynamic stalls were analyzed. These accidents involved structurally and mechanically sound aircraft decelerating through the 1.3VStall buffer to the stall airspeed i.e. a Controlled Flight into Stall (CFIS). The analysis produced three main observations: First, the accidents were “functional complexity” failures -the resu...

A detailed numerical study has been carried out to investigate the effects of leadingedge protuberance as a novel flow-separation control-technique for vertical-axis-windturbine (VAWT). The aerodynamic performance stationary protuberanced blade and an associated H-type Darrieus VAWT made three blades were investigated using unsteady Reynolds-Averaged-Navier-Stokes (URANS) Implicit Large Eddy Si...

The stall aerodynamic model based on Kirchhoff’s theory of flow separation is widely used in the identification and modeling parameters. However, it has two defects. First, its structure significantly different from pre-stall for a small attack angle, meaning results cannot be combined with to form full flight envelope model. Second, pitching moment model, which conjunction Kirchhoff lift accur...

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 ...

A gradient-based Newton–Krylov algorithm for aerodynamic shape optimization is applied to lift maximization of a multi-element landing configuration. The governing flow equations are the two-dimensional compressible Navier–Stokes equations in conjunction with a one-equation transport turbulence model. The objective function gradient is computed via the discrete-adjoint method. The design exampl...

This paper deals with the optimization of a synthetic jet actuator parameters in the control flow around the NACA0015 airfoil at two angles of attack: 13° (i.e. the stall angle of NACA0015) and 16° (i.e. the post stall angle of NACA0015) to maximize the aerodynamic performance of the airfoil. Synthetic jet actuator is a zero mass flux-active flow control device that alternately injects and remo...

Abstract Dynamic stall on an airfoil comprises a series of complex aerodynamic phenomena in response to an unsteady change of the angle of attack. It is accompanied by a lift overshoot and delayed massive flow separation with respect to static stall. The classical hallmark of the dynamic stall phenomenon is the dynamic stall vortex. The flow over an oscillating OA209 airfoil under dynamic stall...

ASWING is a program for the prediction of static and quasi-static loads and deformations of aircraft with flexible high aspect ratio surfaces and fuselage beams. The key features of the overall structural/aerodynamic model are sketched in Figure 1. A fully nonlinear Bernoulli-Euler beam representation is used for all the surface and fuselage structures, and an enhanced lifting-line representati...

An inviscid double wake model based on a steady two-dimensional panel method has been developed to predict aerodynamic loads of wind turbine airfoils in the deep stall region. The separated flow is modelled using two constant vorticity sheets which are released at the trailing edge and at the separation point. A calibration of the code through comparison with experiments has been performed usin...

This paper describes the introduction of three-dimension (3-D) blade designs into a 5-stage axial compressor with multi-stage computational fluid dynamic (CFD) methods. Prior to a redesign, a validation study is conducted for the overall performance and flow details based on full-scale test data, proving that the multi-stage CFD applied is a relatively reliable tool for the analysis of the foll...