Search

Ion wind propulsion systems have potential applications in the field of unmanned aerial vehicle due to their compactness, quiet operation, and simple design. Previous studies have focused on the influences of power source, electrode arrangement, size, and shape on the output thrust characteristics. However, few studies have been performed on the environmental conditions, which can be beneficial for the practical applications of ion wind aircraft in various climatic conditions. In this work, a measurement platform of the output characteristics of ion wind propulsion system under various environmental conditions has been established. The experimental pressure range was 1–0.7 atm, and the relative humidity (RH) range was 30%–92%. The effects of air pressure and humidity, and voltage level on the thrust, thrust-to-power radio (TPR) corona current have been investigated. The results showed that the corona current and thrust of the wire-wing electrode array decreased with RH within the range of 30%– to 80%. Under higher humidity, the corona current and thrust tend to increase at most voltage levels. Moreover, the thrust and current both decreased with reduced pressure when keeping the voltage-to-pressure ratio (U/P) unchanged. It was also found that the thrust was roughly proportional to the square of the pressure. Finally, the possible explanations of the coupled influences on the output characteristics were discussed. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Data on experiments with discharges over dielectrics in the form of powder of Al2O3, SiO2, soil, etc. are presented. Discharges developed under the upper electrode in the form of a needle or a set of needles. A cuvette filled with a substance was used as the lower electrode, to which grounding was applied. The appearance of jets and their destruction into droplets reflect the development of hydrodynamic phenomena over charged liquids. In the case of a dispersed electrode (electrodes), a funnel (funnels) or complex pointed structures, more complex shapes, etc. appear on the surface under the action of hydrodynamic flows. The surface temperature of the liquid is measured using a thermal imager. A qualitative interpretation of the results is given. [ABSTRACT FROM AUTHOR]

The ion wind ability to initiate motions in the originally motionless warm fog inside an enclosed volume is studied. The objective of the study is the experimental check of the possibility to exploit corona discharges for the warm fog modification. The experiment was carried out in a specialized laboratory unit in the Fedorov Institute of Applied Geophysics. The possibility of using the unit to explore the effect of corona discharges on warm fogs is clearly demonstrated. [ABSTRACT FROM AUTHOR]

The results of studies evaluating the efficiency of fog dispersion by collecting water droplets contained in the fog using the grid electrostatic precipitator are considered. The precipitator includes a corona discharge generation system that provides electric charging of fog droplets and a grounded gauze structure free for airflow. When air flows through the cells of the grounded conductive gauze, electrically charged drops are deposited on its surfaces and are separated from the wind stream. The airflow purified from drops is directed to the protected area and forces fog out of it. Data of the presented studies are based on the experiments conducted in the large aerosol chamber of the Institute of Experimental Meteorology (Taifun Research and Production Association). High efficiency of the investigated method is shown, it may be recommended for practical work to improve visibility in fog in a controlled area. [ABSTRACT FROM AUTHOR]

An experimental study of the velocity field in a three-electrode arrangement of a plasma-chemical surface dielectric barrier discharge (SDBD) reactor designed for plant seed’s treatment was carried out. The effect of polarity and magnitude of the extraction voltage (potential of the third electrode), configuration of the SDBD system (5- and 10-mm distances between the strips were observed) and the permeability for gas flow of the third electrode (in the form of a plate or a grid) on the magnitude of the extraction ion current, and induced gas flow structure were analyzed. It is shown that the most uniform flow in the direction of the third electrode, necessary for uniform seed treatment, is achieved in the case of a permeable third electrode under positive displacement potential, opposing a surface discharge electrodes with a distance between the strips much less than the gap dimensions (5 mm between the strips with 10 mm between the third electrode and the barrier surface). [ABSTRACT FROM AUTHOR]

We report on experimental observations of the deformations of a free surface of superfluid 4 He in the presence of the corona discharge above the liquid. The effect is attributed to the impact of the ion wind generated by the discharge. [ABSTRACT FROM AUTHOR]

Ion winds dominate the effects observed when an external electric field is applied to a hydrocarbon flame. Such effects require, however, a sufficient ion source to generate the ion wind. Electric field combustion studies rarely report the rate of ions passing through the system. Current voltage curves, I-V curves, represent how effectively electrical energy is converted into kinetic energy in the flow. This study experimentally obtains I-V curves for different non-premixed burner configurations. The results show that the burner configuration has a significant effect, particularly with field strengths above the saturation point. Increased ion current above saturation and ion current/flame instabilities were observed. Experiments also show that secondary ionization can account for a portion of the increase in ion current, but flame contours point to a stronger correlation with flame geometry and the ability of an ion wind to enhance localized mixing by promoting air entrainment. [ABSTRACT FROM AUTHOR]

We present a simple and efficient airflow generator utilizing the effect of ion wind by generating simultaneously both the positive and negative ions from two sharp electrodes mounted parallel to each other. The unique bipolar geometrical setup eliminates the effect of space charge by the high recombination rate of oppositely charged ions. The two-electrode arrangement is symmetrical, where the electrode creating charged ions of one polarity also serves as the reference electrode to establish the electric field required for ion creation by the opposite electrode, and vice versa. Unlike the conventional setup, with a single electrode generating ion wind with movement toward the reference electrode, in this configuration the air movement is parallel to the electrodes, and is directed away from the device. The airflow behavior is studied by both experiments and numerical simulation. The ion wind speed has a linear relationship with the square root of the discharge current, U\propto \sqrt I , and its measured values agree well with simulation. The characterization of the discharge current–voltage relationship was derived from mathematical processing in the general form I=b( V-Vo )^{n} . The ion wind speed and the current–voltage characteristics depend on the interspace between the electrodes and the electrode geometry. An ion wind speed on the order of ms ^-1 is created with a microampere discharge current, resulting in a total net charge of only several femtoampere. The proposed configuration is beneficial in minimizing the power consumption of the system, and in enabling air recirculation for airflow control applications, cooling applications, propulsion technology, and micropump design, especially for the applications where neutralized ion wind flow is required. [ABSTRACT FROM AUTHOR]

The 'ion wind', a gas-dynamic flow in the corona discharge that arises owing to transfer of the ion component momentum to the neutral particles of an initially stationary gas, and its interaction with the external flow perpendicular to it are studied. A physico-mathematical model of the flows considered is proposed and the corresponding equations are analyzed numerically. The boundary conditions used for the electric quantities approximately model the conditions in the negative corona discharge between a thin corona-forming electrode and a plane grid electrode transparent to the gas. [ABSTRACT FROM AUTHOR]

Electric fields applied to flames can be used to impart force directly on the reaction zone and local surroundings due to the presence of flame ions. The resultant electric body force modifies the flow field surrounding the combustion environment. This paper describes a numerical simulation of the flow field of entrained gases and exhaust surrounding a gaseous fuel flame when it is exposed to electric fields by formulating the problem as a unipolar two fluid system (neutrals and positive ions). An analysis, performed at steady state, is verified by comparison to published experimental results (total current, current density profiles, and qualitative flow measurements). The results indicate a complex interaction between the combustion and current discharge environments where the flow field is dominated by the presence of a toroidal vortex structure and the discharge is dominated by space charge effects. In addition, a transient analysis of the flow field is performed, and four fundamental timescales in the system are identified. These timescales are (1) steady state discharge establishment, (2) plume establishment, (3) vortex establishment, and (4) heating of the feed tube. Timescales (1)-(3), being the fastest timescales of the system, are evaluated and compared. The results show good agreement between computational and analytical timescale values. [ABSTRACT FROM AUTHOR]

Electric fields applied to combustion plasmas can be used to manipulate the thermofluid flow field to reduce buoyant forces and, hence, convection in locations near and within the flame. The resulting flow field is similar to that which is obtained in microgravity. Previous work has shown that buoyancy is modified in a non-premixed methane-air capillary flame when it burns in a capillary-to-plane configuration and an electric field is applied, and that regions of neutral or microbuoyancy exist, as indicated by the examined temperature and oxidizer profiles. The aim of this article is to examine in more detail this microbuoyancy condition and the coupling between the ion wind and resulting thermofluid flow field. To this end, the voltage-current characteristics (VCC) of CH4, C2H2, C2H4, C2H6, and C3H8 are measured and compared. Soot generated in the C2HX and propane flames lead to a hysteresis in the VCC curve whereby increased sooting leads to lower ion currents at constant flow rates and applied potentials. Buoyancy regimes for these flames in this configuration are determined. Methane can achieve the highest flow rate without sooting at the microbuoyant condition, and does not exhibit hysteresis in the VCC for the flow rates examined here. Furthermore, in this geometry, the microbuoyant condition for methane is found to coincide with ion current saturation when the capillary-to-plane distance is varied. These results allow for several simplifications to be made when modeling the flame at these conditions: the imposition of a spherical flame boundary with known ion current, and negligible recombination in the domain. [ABSTRACT FROM AUTHOR]

Transport control by large electric fields in microgravity may be subdivided according to whether the charge carriers are flame ions, ions produced by corona discharges, or electrically charged particles. Using electric fields to induce and direct convection through the drag exercised on neutral gas by ions and to manipulate dispersions and trajectories of electrically charged droplets and particles is especially effective in the absence of Earth's gravity. We have explored applications associated with each of these, and this review collects and summarizes briefly the principal findings of our research, which is scattered widely over the literature of combustion, electrostatics, and experimental science. [ABSTRACT FROM AUTHOR]

Using an electrical discharge to control airflow has recently been an active area of research. This is mostly because of the interest in the manipulation of free airflow for aerodynamic applications. Corona discharges are well suited for these applications. In this paper, we present photographs illustrating the ion wind effect in a clear visual manner. The device used is a positive corona discharge between the end of sharp wires and a grounded mesh electrode. Measurements of the average wind speed as a function of the applied voltage for two different gap distances are presented. [ABSTRACT FROM AUTHOR]