Acoustic signature of a rigid wing, equipped with a movable downstream flap and interacting with a line vortex, is studied in a two-dimensional low-Mach number flow. The flap is attached to the airfoil via a torsion spring, and the coupled fluid-structure interaction problem is analyzed using thin-airfoil methodology and application of the emended Brown and Michael equation. It is found that in...

Formulae expressing explicitly the coefficients of an expansion of double Jacobi polynomials which has been partially differentiated an arbitrary number of times with respect to its variables in terms of the coefficients of the original expansion are stated and proved. Extension to expansion of triple Jacobi polynomials is given. The results for the special cases of double and triple ultraspher...

The considered multi-point (multi-objective) optimization problem is characterized by a multi-modal, nonlinear topology and a highly sophisticated evaluation of the objective function, thus requiring an efficient, direct global optimization algorithm. Evolution strategies have shown their capabilities for solving complex optimization problems with continuous variables in a variety of applicatio...

An episodic unsupervised learning simulation using the Q-Learning method is developed to learn the optimal shape and shape change policy for a problem with four state variables. Optimality is addressed by reward functions based on airfoil properties such as lift coefficient, drag coefficient, and moment coefficient about the leading edge representing optimal shapes for specified flight conditio...

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...

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...