Polarity Effect and Flow Characteristics of Wire-Rod Type Electrohydrodynamic Gas Pump
The electrohydrodynamic (EHD) flow characteristics for a wire to rod type EHD gas pump have been experimentally investigated. Experiments were conducted for DC negative and positive applied high voltage to a corona wire of diameter 0.24 mm from 0-24 kV, grounding rod electrode diameter from 1.5 mm to 3.1 mm and wire/rod electrode distance to pipe diameter ratio from 0.63 to 1.16. It was observed that the polarity plays an important role, where a negative high voltage generates a higher gas flow than that of a positive polarity. The results show that a maximum of 40 L/min of gas flow rate is generated at 0.37 W energy input when the pipe diameter is 20 mm with the corona wire electrode and grounding rod electrode gap distant set to 12.6 mm under negative applied voltage compared to 25 L/min at 0.23 W energy input for the positive case at the same specific energy density.
Integrated Ionic Flow Device and Heat Sink as a Fan Sink Alternative
The norm for component cooling in the server industry today is passive heat sinks utilizing system level airflow. While the larger fans supplying the air flow can be made very efficient, they typically consume large amounts of power. Ionic air moving devices are under investigation in many industries, including the computer industry, as a low power alternative. Ionic devices are not capable of the same high-velocity airflows as axial fans and blowers, but have the advantage of being made part of the heat sink, providing sufficient localized flow. A small axial fan supplying local air flow to a heat sink was compared to an ionic device incorporated into the heat sink to compare power consumed, while cooling a simulated component to a reasonable temperature. It was shown that the ionic device provided the same cooling for an input of 0.17 W compared to the fan at 0.40W. Local cooling represents a paradigm shift from system level cooling, but these data show that in this new paradigm, the ionic devices can provide cooling at lower power input than conventional axial fans.
An analytical approach to the design of electrodes in high-power, fast-transverse-flow CO2 lasers
Abstract Usually, the design of the electrodes of fast-transverse-flow CO 2 lasers relies more on experimental data than on theoretical analysis. Traditional systems sustain a stable, high-power discharge but the current distribution generates a peaked, non-uniform small-signal-gain pattern. We present a theoretical model suitable for the design of electrodes that achieves a quasi uniform gain distribution. The analysis, based on a two-temperature model and the gas-transport equations, computes the electron density that supports a flat gain pattern. Combining the desired electron density with the electron-balance equations, the model determines the required electric field. The results were used to design a new set of electrodes for a home-made fast transverse flow CO 2 laser. A stable, large volume discharge ( 4 × 8 × 90 cm 3 ) with very good uniformity was obtained. The resulting gain distribution was registered in a bi-dimensional map. The peak gain rose from 1.2 m - 1 , attained with the old electrode set, to 1.6 m - 1 with the new one and the gain showed a homogeneous profile.