This paper numerically investigates the effect of chordwise flexibility on the dynamic stability of compliant airfoils. A classical two-dimensional aeroelastic model is expanded with an additional degree of freedom to capture time-varying camber deformations, defined by a parabolic bending profile of the mean aerodynamic chord. Aerodynamic forces are obtained from unsteady thin airfoil theory a...

This paper presents an investigation on the effect of introducing large-scale roughness through static curvature modifications on the low speed flow over an airfoil. The surfaces of a standard Eppler 398 airfoil have been modified with regular perturbations or “bumps” of the order of 2%c for this purpose. While the actual E398 airfoil is not a suitable candidate for low Re cases due to extensiv...

this paper presented methods to determine the aerodynamic forces that acton an aircraft wing during flight. these methods are initially proposed for asimplified two degree-of-freedoms airfoil model and then are extensivelyapplied for a multi-degree-of-freedom airfoil system. different airspeedconditions are considered in establishing such methods. the accuracy of thepresented methods is verifie...

An experimental study of static and dynamic pressure distributions over a NACA 0012 airfoil in the two-dimensional test section 0.8 × 0.4-meter of a transonic wind tunnel is presented. Tests are conducted at freestream Mach numbers from 0.35 to 0.89, and angle of attack between −2.0 and 15, and Reynolds number based on the airfoil chord length of 3.0 million. Tests are performed at boundary-lay...

In this paper the implementation of shape optimization techniques based on genetic algorithms for airfoil design is presented. The shape of an airfoil is sought such that a cost function depending on the scattered electromagnetic wave and the pressure distribution on the airfoil is minimized. The combined electromagnet-ics//ow problem is modeled by Helmholtz equation and potential ow. The state...

The permeability of the preform composite materials used in liquid molding processes such as resin transfer molding and structural reaction injection molding is a complex function of weave pattern and packing characteristics. The development of tools for predicting permeability as a function of these parameters is of great industrial importance. Such capability would speed process design and op...

Computational aeroacoustic methods are applied to the modeling of noise due to interactions between gusts and the leading edge of real symmetric airfoils. Single frequency harmonic gusts are interacted with various airfoil geometries at zero angle of attack. The effects of airfoil thickness and leading edge radius on noise are investigated systematically and independently for the first time, at...

An adjoint-based Navier–Stokes design and optimization method for two-dimensional multi-element high-lift configurations is derived and presented. The compressible Reynolds-averaged Navier–Stokes equations are used as a flow model together with the Spalart–Allmaras turbulence model to account for high Reynolds number effects. When a viscous continuous adjoint formulation is used, the necessary ...

This paper presents a numerical analysis of the performance of a three-bladed Darrieus vertical-axis wind turbine based on the DU91-W2-250 airfoil. A complete campaign of 2-D simulations, performed for several values of tip speed ratio and based on RANS unsteady calculations, has been performed to obtain the rotor torque and power curves. Rotor performances have been compared with the results o...

In many aerospace engineering design problems, objective function evaluations can be extremely computationally expensive, such as the optimal design of the aerodynamic shape of an airfoil using high-fidelity computational fluid dynamics (CFD) simulation. A widely used approach for dealing with expensive optimization is to use cheap global surrogate (approximation) models to substitute expensive...