Aerodynamic Influence of a Finite-Span Flap on a Simple Wing

The results of a wind-tunnel test are presented for a two-dimensional NASA 63(sub 2)-215 Mod B airfoil with a 30% chord single-slotted flap. The use of lift-enhancing tabs (similar to Gurney flaps) on the lower surface near the trailing edge of both elements was investigated on four nap configurations. A combination of vortex generators on the flap and lift-enhancing tabs was also investigated. Measurements of surface-pressure distributions and wake profiles were used to determine the aerodynamic performance of each configuration. By reducing flow separation on the flap, a lift-enhancing tab at the main-element trailing edge increased the maximum lift by 10.3% for the 42-deg flap case. The tab had a lesser effect at a moderate flap deflection (32 deg) and adversely affected the performance at the smallest flap deflection (22 deg). A tab located near the flap trailing edge produced an additional lift increment for all flap deflections. The application of vortex generators to the flap eliminated lift-curve hysteresis and reduced flow separation on two configurations with large flap deflections (greater than 40 deg). A maximum-lift coefficient of 3.32 (17% above the optimum baseline) was achieved with the combination of lift-enhancing tabs on both elements and vortex generators on the flap.

/pdf/experimental-study-of-lift-enhancing-tabs-on-a-two-element-caqg4en5lj.pdf

Experimental Study of Lift-Enhancing Tabs on a Two-Element Airfoil

The current study computationally examines one of the principal three-dimensional features of the e ow over a high-lift system, the e ow associated with a e ap edge. Structured, overset grids were used in conjunction with an incompressible Navier ‐Stokes solver to compute the e ow over a two-element highlift cone guration. The computations were run in a fully turbulent mode using the one-equation Baldwin‐Barth model. Specie c emphasis was given to the details of the e ow in the vicinity of the e ap edge, and so the geometry was simplie ed to isolate this region. The geometry consisted of an unswept wing, which spanned a wind-tunnel test section, equipped with a single-element e ap. Two e ap cone gurations were computed: a full-span and a half-span Fowler e ap. The chord-based Reynolds number was 3.7 3 10 6 for all cases. The results for the full-span e ap agreed with two-dimensional experimental results and verie ed the method. Grid topologies and related issues for the half-span e ap geometry are discussed. Results of the half-span e ap case are compared with three-dimensional experimental results, with emphasis on the e ow features associated with the e ap edge. The results show the effect of the vortex created by the e ap edge, including the impact on e ow separation and spanwise lift distribution.

Navier-Stokes Analysis of the Flow About a Flap Edge

Three-dimensional multi-element wings are simulated to investigate slat and flap aerodynamics using Detached-Eddy Simulation. The computations are performed by solving the Navier-Stokes equations on unstructured grids. All of the computed cases include the main wing with a half-span flap deflected to 39 degrees and a three-quarter-span slat deflected to 6 degrees. Computations of the model, which simulates a landing configuration at 10 degrees angle of attack and a chord-based Reynolds number of 3.7 million, are validated with surface pressure measurements acquired at the NASA Ames 7by 10-Foot Wind Tunnel. The results increase the computational knowledge of how to accurately model the flow physics of a multi-element wing with three-dimensional flow by using DetachedEddy Simulation.

/pdf/detached-eddy-simulation-of-slat-and-flap-aerodynamics-for-a-1ylrq9jgqt.pdf

Detached-Eddy Simulation of Slat and Flap Aerodynamics for a High-Lift Wing

https://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=1002&context=aero_fac

Navier–Stokes analysis of lift-enhancing tabs on multi-element airfoils

An upper surface modification designed to increase the maximum lift coefficient of a 63 sub 2 - 215 airfoil section was tested at Mach numbers of 0.2, 0.3, and 0.4 Reynolds numbers of 1.3 x 1 million, 2 x 10 sub 6 and 2.5 x 1 million. Comparisons of the aerodynamic coefficients before and after the modification were made. The upper surface modification increased the maximum lift coefficient of the airfoil significantly at all conditions.

https://ntrs.nasa.gov/api/citations/19790005853/downloads/19790005853.pdf

E. T. Schairer

Papers

Effects of upper surface modification on the aerodynamic characteristics of the NACA 63 sub 2-215 airfoil section