An investigation has been made into the application of the theory of thin sections to the design of hydrofoils having high cavitation speeds. Consideration is given to both symmetrical sections, which themselves are suitable for struts, and camber-lines, which, when used with the symmetrical sections, lead to cambered sections which are suitable for lifting surfaces. In all the aim has been to ...

Adaptive airfoils and wings can provide superior performance at the expense of increased cost and complexity. In this paper, an aerodynamic optimization algorithm is used to assess an adaptive airfoil concept for drag reduction at transonic speeds. The objective is to quantify both the improvements in drag that can be achieved and the magnitude of the shape changes needed. In an initial study, ...

We discuss a new numerical scheme involving adaptive boundary conditions which allows to compute, at very low Reynolds numbers, drag and lift of airfoils with rough surfaces efficiently with great precision. As an example we present the numerical implementation for an airfoil consisting of a line segment. The solution of the NavierStokes equations is singular at the leading and the trailing edg...

1. Introduction While aerodynamic prediction methods based CFD are now well established , and quite accurate and robust, the ultimate need in the design process is to find the optimum shape which maximizes the aerodynamic performance. One way to approach this objective is to view it as a control problem, in which the wing is treated as a device which controls the flow to produce lift with minim...

This paper gives a quantitative account of the influence slipstream on aerodynamic performance contrarotating propeller (CRP)/wing system, and compares it with CRP clean wing. To accurately evaluate complex interaction, unsteady Reynolds-averaged Navier–Stokes approach using sliding mesh method is performed at typical freestream velocity 30 m/s. Four different critical parameters, including ang...

An analysis is performed to study the supersonic flow over conical bodies of three different cross sections circular, elliptic and squircle (square with rounded corners) shaped. Perturbation method is applied to find flow variables analytically. In order to find lift and drag forces the pressure force on the body is found, the component along x is drag and the component along z is lift. Three e...

This paper discusses two adaptive feedback control approaches designed to reattach a massively separated flow over a NACA airfoil with minimal control effort using piezoelectric synthetic jet actuators and various sensors for feedback. One approach uses an adaptive feedback disturbance rejection algorithm in conjunction with a system identification algorithm to develop a reduced-order dynamical...

Drag reduction of an object is the major concern in many engineering applications. Experimental studies have been carried out on circular cylinder with helical grooves in a subsonic wind tunnel. Different cases of helical grooves with different pitches, helical groove angles and number of starts of helical groove on circular cylinder are tested. Experimental results show the drag coefficient is...

To indicate the best airfoil profile for different sections of a blade, five airfoils; included S8xx, FFA and AH series was studied. Among the most popular wind power blades for this application were selected, in order to find the optimum performance. Nowadays, modern wind turbines are using blades with multi airfoils at different sections. SST-K-ω model with different wind speed at large scale...

The problem of determining the low Reynolds number lift and drag on a flat plate in Oseen flow is treated by the application of a variational principle due to Levine and Schwinger. This approach circumvents the difficulty which has limited previous results to drastically low values of the Reynolds number. In particular, an asymptotic form for the drag coefficient is derived, and found to be sui...