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 & Microstructure. The organization has 5817 authors who have published 9157 publications receiving 292559 citations. The organization is also known as: Wright-Patterson AFB & FFO.

Numerical simulation of nanosecond-pulse electrical discharges

Abstract: Recent experiments with a nanosecond-pulse, dielectric barrier discharge at the stagnation point of a Mach 5 cylinder flow have demonstrated the formation of weak shock waves near the electrode edge, which propagate upstream and perturb the bow shock. This is a promising means of flow control, and understanding the detailed physics of the conversion of electrical energy into gas motion will aid in the design of efficient actuators based on the concept. In this work, a simplified configuration with planar symmetry was chosen as a vehicle to develop a physics-based model of nanosecond-pulse discharges, including realistic air kinetics, electron energy transport, and compressible bulk gas flow. A reduced plasma kinetic model (23 species and 50 processes) was developed to capture the dominant species and reactions for energy storage and thermalization in the discharge. The kinetic model included electronically and vibrationally excited species, and several species of ions and ground state neutrals. The governing equations included the Poisson equation for the electric potential, diffusion equations for each neutral species, conservation equations for each charged species, and mass-averaged conservation equations for the bulk gas flow. The results of calculations with this model highlighted the path of energy transfer in the discharge. At breakdown, the input electrical energy was transformed over a time scale on the order of 1?ns into chemical energy of ions, dissociation products, and vibrationally and electronically excited particles. About 30% of this energy was subsequently thermalized over a time scale of 10??s. Since the thermalization time scale was faster than the acoustic time scale, the heat release led to the formation of weak shock waves originating near the sheath edge, consistent with experimental observations. The computed translational temperature rise (40?K) and nitrogen vibrational temperature rise (370?K) were of the same order of magnitude as experimental measurements (50?K and 500?K, respectively), and the approach appears promising for future multi-dimensional calculations. The effectiveness of flow control actuators based on nanosecond-pulse, dielectric barrier discharges is seen to depend crucially on the rapid thermalization of input energy, in particular the rate of quenching of excited electronic states and the rate of electron?ion recombination.

Novel Solid Polymer Electrolytes with Single Lithium-Ion Transport

Abstract: State-of-the-art poly(ethylene oxide) (PEO)-based polymer electrolytes have a t Li+ much lower than I; it is typically around 0.2-0.3. Thus, the development of single-cation-conductive, solvent-free polymer electrolytes is considered of prime importance for the progress of the technology of lithium batteries. Attempts mainly directed at immobilization of the anion in the polymer architecture have been reported in the past, but with only modest success because this approach generally depresses the conductivity to unacceptably low values. In this work, we report an alternative, new approach based on the addition to the PEO-LiX blend of an anion-trapping supermolecular component. In this way, polymer electrolytes with unity values of t Li+ but still maintaining a true solid configuration combined with appreciable conductivity have been obtained. To our knowledge, this strategy has never been used, and we believe that this breakthrough result is associated with the immobilization of the anion (X - ) by the additive and, possibly, by an ordering of the PEO-LiX system.

Dual-pump coherent anti-Stokes Raman scattering measurements of nitrogen and oxygen in a laminar jet diffusion flame

Abstract: Dual-pump coherent anti-Stokes Raman scattering (CARS) has been demonstrated for the simultaneous measurement of gas-phase temperature and concentrations of molecular nitrogen and oxygen. A polarization technique was used to vary the relative intensities of the two CARS signals and expand the dynamic range of the relative concentration measurements. Detailed temperature and oxygen mole fraction measurements were performed in the stabilization region of a hydrogen-nitrogen jet diffusion flame. These results indicate that there is a region below the nozzle exit where significant amounts of oxygen are found on the fuel side of the peak flame temperature profile.