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In this paper, a coupled aerothermoelastic dynamic stability analysis of composite aerovehicle wings featuring nonclassical effects, and immersed in an incompressible gas flow is developed. Specifically, the study concerns the aerothermoelastic stability of swept wings made of advanced composite materials and exposed to a heat flow generated by a laser beam impacting its deformed surface. Because of its exceptional features in thermal insulation of aerospace structures, the pyrolytic graphite is adopted in the actual numerical simulations together with consideration of a rectangular single-layered swept wing. The evaluation of the temperature field on the deformed (actual) configuration of the wing permits the authors to address the problems of the aerothermoelastic response and stability in a coupled framework. As a result, the exact analytical expression of the aerothermoelastic response of the heated wing is obtained in the Laplace space domain and, following it, the static and dynamic aeroelastic instabilities are determined. The obtained results indicate that the aeroelastic stability is substantially affected by the thermoelastic coupling. In the presentation and discussion of the results, special attention is given to the effects played by the flight speed, thermal anisotropy of the material constituent, ratio of the characteristic thermal time to the natural period of vibration, and direction of the external heat flux impacting the wing surface.

Pneumatic servo values play a significant role in power transmission and system control using a pressurized gas. When pressurized air passes through servo values, noise and pressure fluctuations are often experienced at the downstream side, and such fluctuations limit the value's efficiency. In this paper, a novel four-port nozzle-flapper-type servo valve using a slit structure instead of an orifice plate is proposed. The slit structure maintains a laminar flow condition, and this provides an opportunity for the minimization of the noise and pressure fluctuations. The slit structure is fabricated using etching technology. The flow characteristics of the slit are investigated theoretically and experimentally in order to evaluate the design specifications and characteristics of the valve. The experimental results indicated that the noise level decreased by approximately 15 dB and could reduce the pressure fluctuation by 75%, compared with the previous valve. It is felt that the valve is more effective than many current valves. [DOI: 10.1115/1.2717617]

An expression for loss-front velocity of magnetically insulated ion flow in a vacuum transmission line is developed. It agrees well with the results from particle-in-cell simulations at high voltage. Index Terms--Loss-front, magnetically insulated ion flow, particle-in-cell, simulation, transmission line.

The reattachment process is an essential part of the dynamics of thermal plasma flows. Simulations of the flow inside a direct-current arc plasma torch performed with a two-temperature model produce a reattachment process triggered by local flow instabilities and driven by local high electric fields and electron temperatures. These results indicate that an arc reattachment can occur not only due to a breakdown of the gas surrounding the plasma but also due to the macroscopic characteristics of the flow, and these emphasize the importance of nonlocal thermodynamic equilibrium-based models to properly describe arc dynamics. Index Terms--Arc reattachment, finite element method, non-equilibrium, plasma torch, thermal plasma.

Plasma jet device, which generates plasma in open space rather than in a confined electrode gap only, attracts lots of attention recently. The generation of a plasma jet could be a gas flow phenomenon, an electrical phenomenon, or both. In this paper, the effect of electric field on the length of a special designed plasma jet is investigated. The plasma jet is driven by a pulsed direct current (DC) power supply. Simulation of the electric potential along the plasma jet shows that the electric potential difference along the 4 cm plasma jet is about 400 volts for applied voltage of 4 kV. This is consistent with the measured electric potential along the plasma jet. Besides, the experiment results also show that the length of the plasma jet reaches its maximum when the pulse width is about 1 [micro]s. According to the measured current-voltage curves, it could be concluded that the effect of pulse width on the length of the plasma jet is solely due to the electric field effect. Index Terms--Atmospheric pressure plasma, dielectric barrier disharge, non-equilibrium plasma, plasma jet, pulsed DC voltage.

In this paper, stable atmospheric dc glow microplasmas generated along two intersecting miniature gas flows through nozzle electrodes are observed. The intersecting angle was varied from 45[degrees] to 135[degrees]. If argon gas flow was used, striation structure can be noticed at the cathode side. Index Terms--Atmospheric glow discharge, intersecting miniature gas flows, microplasma-jets, striation stricture.