The paper presents the design and the construction of the power part of a three-way pneumatic valve that uses a pilot stage developed by Belforte et al., based on a compact turbulent amplifier that uses the laminar-turbulent transition of fluidic jets. The valve can be used to drive a power stage of pneumatic circuits. It has a low energy consumption to switch. The pilot stage uses an acoustic signal generated by a piezoelectric device to brake the laminar flow. The power part of the valve has been designed to obtain an high conductance and a good dynamic performance. The design of the power valve, by a mathematical model using concentrated parameters, is presented. The prototype was constructed and tested. The results of the experimental test are also reported and discussed.

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The nozzle-flapper valves are widely applied as a pilot stage in aerospace and military system. A subject of the analysis presented in this work is to find out a reasonable range of null clearance between the nozzle and flapper. This paper has presented a numerical flow coefficient simulation. In every design point, a parameterized model is created for flow coefficient simulation and cavitation under different conditions with varying gap width and inlet pressure. Moreover, a new test device has been designed to measure the flow coefficient and for visualized cavitation. The numerical simulation and test results both indicate that cavitation intensity gets fierce initially and shrinks finally as the gap width varies from small to large. From the curve, the flow coefficient mostly has experienced three stages: linear throttle section, transition section and saturation section. The appropriate deflection of flapper is recommended to make the gap width drop into the linear throttle section. The flapper-nozzle null clearance is optionally recommended near the range of DN/16. Finally through simulation it is also concluded that the inlet pressure plays a little role in the influence on the flow coefficient.

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The purpose of this investigation is to develop the flapping-wing micro air vehicles based on dragonflies. We attempted to product mechanical flapper based on dragonflies. The flow fields and aerodynamic force of the mechanical flapper were measured with dynamic PIV system. The flow field around the mechanical flapper was almost the same as that of dragonfly. The leading edge separation and wake capture process can be observed. The aerodynamic force of the mechanical flapper was proportional to the second powers of the flapping frequency. The aerodynamic lifting force of the mechanical flapper was 0.68 times of weight the flapper at the flapping frequency of 37.6 Hz. It corresponded to twice of dragonflies' weight, it therefore indicated that the mechanical flapper generated sufficiently large enough to lift the dragonflies.

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