Wright-Patterson Air Force Base

About: Wright-Patterson Air Force Base is a other organization based out in Wright-Patterson AFB, Ohio, United States. It is known for research contribution in the topics: Laser & Mach number. The organization has 5817 authors who have published 9157 publications receiving 292559 citations. The organization is also known as: Wright-Patterson AFB & FFO.

Aerodynamic and Aeroelastic Characteristics of Wings with Conformal Control Surfaces for Morphing Aircraft

Abstract: Investigations are conducted on lifting surfaces with conventional and conformal trailing-edge control surfaces. The Sohngen inversion formula is used with the thin-airfoil integral equation to determine the aerodynamic pressure for various control surface chord-to-airfoil chord ratios. Comparisons to a conventional control surface show increases in lift and pitching moment of the airfoil with a conformal control surface. Aerodynamic pressure distributions acting on a wing with control surfaces are determined with the vortex lattice technique. Predicted aerodynamic pressures and roll moments are compared to available wind-tunnel data and provide a more general understanding of theaerodynamicbehavior observed there. Roll performance of a rectangular wing is determined for various control surface chord-to-wing chord ratios. It is found that the maximum roll rate is greater for a wing with a conformal control surface, but has a lower reversal dynamic pressure than the wing with a conventional control surface. The aerodynamic and aeroelastic results obtained from this investigation provide some insight for wings designed with conformal control surfaces.

Photomotility of polymers.

Abstract: The demand for soft robots urges the development of new light-responsive materials for remotely powered actuation. Here, Wie et al. show directional motion over centimeter scales using azobenzene-functionalized liquid crystalline polymer films upon continuous radiation from ultraviolet to visible light.

Spray Structures of Liquid Jets Atomized in Subsonic Crossflows

Abstract: The structures of spray plumes from 0.5-mm waterjets injected into a subsonic crosse ow were experimentally investigated using phase Doppler particle anemometry. Droplet size, axial velocity, and volume e ux were measured across the spray plume at several axial distances downstream of the injector exit. Results indicate that large droplets can be found in the central portion of the spray plume for cases with small liquid/air momentum e ux ratios and in which the momentum exchange between column waves and the airstream is signie cant. For cases with large-momentum e ux ratios, the droplet size distribution exhibits a concave-layered structure, with the peak on the centerline and large droplets at the top. Droplets were found to concentrate in a small area within the spray plume, which indicates that the liquid mass distribution is not uniform. The height of the maximum volume e ux locations, an indicator of the location of the highest concentration of droplets, was measured and correlated with momentum e ux ratios and axial distances. It was found that more droplets are distributed toward the upper portion of the spray plume for larger momentum e ux ratios. Spray penetration, spray width, penetration-to-width ratio, and spray cross-sectional area were also found to increase with the momentum e ux ratio.

High-Fidelity Simulation of Transitional Flows Past a Plunging Airfoil

Abstract: This investigation addresses the simulation of the unsteady separated flows encountered by a plunging airfoil under low-Reynolds-number conditions (Rec 6 ◊ 10 4 ). The flow fields are computed employing a previously developed and extensively validated high-fidelity implicit large-eddy simulation (ILES) approach. In order to permit comparison with available experimental measurements, calculations are performed first for an SD7003 airfoil section at an angle of attack o = 4 plunging with reduced frequency k = 3.93 and nondimensional amplitude ho = 0.05. Under these conditions, it is demonstrated that for Rec = 10 4 , transitional effects are not significant and that the dynamic-stall vortices remain fairly coherent as they propagate along the airfoil. For Rec = 4 ◊ 10 4 , the dynamic-stall vortex system is laminar at is inception, however shortly afterwards, it experiences an abrupt breakdown associated with the onset of spanwise instability effects. A detailed description of this transition process near the leading edge is provided. The computed phased-averaged structures for both values of Reynolds number are found to be in good agreement with the experimental data. As a second example, the suppression of static stall at high angle of attack ( o = 14 ) is investigated using high-frequency small-amplitude vibrations (k = 10,ho = 0.005). At Rec = 6 ◊ 10 4 , separation is completely eliminated in a time-averaged sense, and the mean drag is reduced by approximately 40%. The instantaneous flow is characterized by the periodic generation of dynamic-stall vortices near the leading edge and by their subsequent transition as they convect close to the airfoil. For Rec = 10 4 , significant reduction of the timeaveraged separation region is still possible with transitional effects present in the aft-portion of the airfoil. For larger forcing amplitude (ho = 0.04,Rec = 10 4 ), a very intriguing regime emerges. The dynamic stall vortex moves around and in front of the leading edge and experiences a dramatic breakdown as it impinges against the airfoil. As a result, the phased-averaged flow displays no coherent vortices propagating along the airfoil upper surface. This new flow structure is also characterized in the mean by the existence of a strong jet in the near wake which manifests in a high value of net thrust. The present study demonstrates the importance of transitional effects for low-Reynolds-number maneuvering airfoils, as well as the suitability of the ILES approch for exploring such flow regime.

Preferential binding of peptides to graphene edges and planes.

Abstract: Peptides identified from combinatorial peptide libraries have been shown to bind to a variety of abiotic surfaces. Biotic–abiotic interactions can be exploited to create hybrid materials with interesting electronic, optical, or catalytic properties. Here we show that peptides identified from a combinatorial phage display peptide library assemble preferentially to the edge or planar surface of graphene and can affect the electronic properties of graphene. Molecular dynamics simulations and experiments provide insight into the mechanism of peptide binding to the graphene edge.