Coefficients Of Wing Research Articles

A new technique for investigating the induced and profile drag coefficients of a smooth wing and a tubercled wing

The induced and profile drag coefficients of a wing are typically determined through a complex experimental technique, such as wake surveying. Such a technique requires measurement of all three orthogonal components of the downstream velocity to find the components of drag, which results in the necessary usage of a sophisticated and costly measurement device, such as multi-hole pressure probe. However, in this paper data is presented which demonstrate that the relative changes in the induced and profile drag coefficients can largely be determined through the sole measurement of the downstream, streamwise velocity. To demonstrate this, the induced and profile drags of two NACA 0021 wings, one with a smooth leading edge and the other wing a tubercled leading edge for comparison, are determined through the measurement of the three orthogonal velocities. The downstream, streamwise velocity distribution of each wing is then constructed and relationships can be determined. The wings were surveyed at 3°, 9°, and 12°. It has been found that the relative magnitude of the profile drag coefficient can be found for all considered angles of attack, while the relative magnitude of the induced drag coefficient can be found at 9° and 12°. These findings produce an innovative, simpler, and more cost effective experimental technique in determining the components of drag of a wing, and reduces the burdensome requirement of a sophisticated measurement device for such an experiment. Further investigation is required to determine the induced drag at 3°.

Aerodynamic Behavior of a Compound Wing Configuration in Ground Effect

The aerodynamic coefficients of wing in ground effect can be affected with its design which can be the main parameter for efficiency of wing-in-ground effect craft. In this study, the aerodynamic coefficients of a compound wing were numerically determined in ground effect. The compound wing was divided into three parts with one rectangular wing in the middle and two reverse taper wings with an anhedral angle at the sides. An NACA6409 airfoil was employed as a section of wings. Three dimensional (3D) computational fluid dynamics (CFD) was applied as a numerical scheme. A realizable k-ε turbulent model was used for simulation the turbulent flow around the wing surfaces. For validation purpose, the numerical results of a compound wing with aspect ratio 1.25, at ground clearance of 0.15 and different angles of attack were compared with the current experimental data. Then, the aerodynamic coefficients of the compound wings were computed at various ground clearances and angle of attack of 4°. According to pressure and velocity distribution of air around wing surfaces, ground clearance had considerable effects on ram effect pressure and tip vortex of the compound wing, and aerodynamic coefficients of the compound wing had some improvements as compared with the rectangular wing.

Influence of transverse slits on the hydrodynamic coefficients of a wing of finite span in stationary and nonstationary motion near a wall

The method of matched asymptotic expansions is used to construct an approximate solution to the problem of the influence of narrow transverse slits on the hydrodynamic coefficients of a thin rectangular wing moving near a wall. The flow in the neighborhood of a slit is described by a local asymptotic solution satisfying the condition of continuity of the pressure on the leading edge of the slit and matched to the main solution. Results of the calculations illustrate the influence of the slits on the hydrodynamic characteristics of the wing at different Strouhal numbers and aspect ratios.