Type Electrohydrodynamic Gas Pump Research Articles

Predicted flow characteristics of a wire-nonparallel plate type electrohydrodynamic gas pump using the Finite Element Method

The aim of this paper is to numerically investigate the interaction between the electrostatic field and the fluid flow in a wire-nonparallel plate configuration of electrodes. The governing equations: Poisson equation for electric field, continuity equation for charge transport and the momentum equation for gas flow were solved using the Finite Element Method assuming a highly non-uniform mesh distribution. The main outcome of this study is the determination of velocity versus pressure characteristics of the pump, which provides useful information for predicting the pump performance and for control purposes. In addition, the efficiency and optimum geometric configuration are evaluated using this model. The numerical results show that a higher voltage leads to larger velocity and higher pressure, where the gas velocity is a linear, but pressure is a non-linear function of the supplied voltage. It was also found that there is an optimum wall angle for which the air volumetric flow rate from the outlet of the pump reaches the maximum value.

Experimental Study on the Velocity and Efficiency Characteristics of a Serial Staged Needle Array-Mesh Type EHD Gas Pump

The ionic wind has good application prospects in the fields of air flow control and heat transfer enhancement. The key for successful applications is how to improve the velocity and how to increase the active area of the ionic wind. This paper designed a needle array-mesh type electrohydrodynamic (EHD) gas pump. The use of needle array electrode where corona discharge started simultaneously could enlarge the active area. The velocity of the ionic wind could increase by placing several single-stage ionic wind generators in series appropriately, called as serial staged generator. The maximum average flow velocity of 16.1 m/s and volumetric flow of 303.5 L/min were achieved at the outlet of a 25-stage gas pump and the conversion efficiency was approximately 2.2%.

Wire-rod type electrohydrodynamic gas pumps with and without insulation cover over corona wire

The effect of an insulation cover on a corona wire for a wire-rod type electrohydrodynamic (EHD) gas pump was experimentally investigated and one-dimensional cross sectional averaged analyses were performed. The insulation cover over the corona wire causes a fluctuation of the discharge current, resulting in fluctuations of the EHD gas flow. The insulation cover also changes the EHD force distribution, which is the product of an electric field and ion charge density. The EHD force concentrated at the center of the flow channel, and was directed toward the rod electrode in a straight line. Thus the rod electrode supposed to become a significant disturbance to the flow. The flow velocity fluctuations and the modified distribution of the EHD force with the insulation cover enlarged the flow head losses, and eventually resulted in smaller flow velocity than that without the insulation cover over the corona wire.

Narrow-Flow-Channel-Driven EHD Gas Pump for an Advanced Thermal Management of Microelectronics

In order to study the feasibility of applying electrohydrodynamic (EHD) gas pumps for advanced thermal management of microelectronics, an experimental investigation was conducted to drive gas flow through a narrow flow channel by an EHD gas pump. The net gas flow induced by corona discharge was generated by a push-fan (PF)-type EHD gas pump with and without a partially covered corona wire and nonparallel ground plate electrodes to transfer gas through millimeter-order circular channels. Therefore, it is important to know the effect of a narrow channel on the characteristics of the EHD gas pump with the corona wire electrode covered. The results show that the effects of narrow circular flow channels significantly influence the flow characteristics of the PF-type EHD gas pump and that the use of an insulator on the corona wire electrode can significantly enhance the current flux density and the pump performance under dc positive applied voltage.

Efficiency of a Wire-Rod Type Electrohydrodynamic Gas Pump Under Negative Corona Operation

A wire-rod type electrohydrodynamic (EHD) gas pump was driven by a negative applied voltage with pipes of different inner diameters. An EHD gas flow was generated from a wire electrode to a rod electrode under a negative corona discharge. The flow velocity was proportional to the applied voltage and the square root of the discharge current. Before spark onset, the maximum volumetric flow rate of 43 L/min was achieved with a pipe having an inner diameter 20 mm, and the pump efficiency was higher than that of a conventional dc motor fan. In a narrow channel, the corona discharge became unstable. In addition, the EHD gas flow velocity was smaller because a pressure loss due to the rod electrode became significant, resulting in a lower electromechanical efficiency.

Flow Distribution Measurement in Wire-nonparallel Plate Type Electrohydrodynamic Gas Pump by a Particle Image Velocimetry

2D Particle Image Velocimetry (PIV) measurements were performed in a wire-nonparallel plates type electrohydrodynamic (EHD) gas pump. The effect of electrode configuration and polarity of the active electrode on the flow pattern inside the pump was studied. One can deduce from the obtained flow patterns that the flow generated inside the EHD pump is three dimensional. The vortices formed inside the EHD gas pump have negative effect on pumping capabilities of the pump since the vortices may block and suppress the generated flow. The PIV results will be compared with a numerical modelling of the flow, based on k-E model.

Effect of Discharge Electrode Parameters on the Flow Velocity Profile of the Wire-rod Type Electrohydrodynamic Gas Pump Exit

Experimental investigation has been conducted to study the effects of corona wire diameter, pipe length, and corona polarity on outlet flow velocity distribution profile of a wire-rod type electrohydrodynamic (EHD) gas pump. Upon applying negative or positive dc high voltage between a wire electrode (outer diameter (o.d.) 60 μm, 200 μm, or 300 μm) and a rod electrode (o.d. 3 mm) in atmospheric air, corona discharge occurs and EHD gas flow is generated in the direction from the wire electrode to the rod electrode through a cylindrical pipe (inner diameter (i.d.) 20 mm). For both polarities, the discharge current and average flow velocity increase monotonically on increasing the applied voltage before the onset of spark discharge. Using wire electrodes with a smaller diameter, stable corona discharge between corona onset and spark onset is generated in a wider voltage range, and the discharge current becomes larger, resulting in a higher flow velocity. The maximum average flow velocity of 2.0 m/s, corresponding to a flow rate of 38 l/min, was achieved with a wire of diameter 60 μm by applying a voltage of -16 kV.

Particle image velocimetry measurements of wire-nonparallel plates type electrohydrodynamic gas pump

2D particle image velocimetry (PIV) measurements were performed in a wire nonparallel plates type electrohydrodynamic (EHD) gas pump. Using simultaneously two CCD cameras allowed obtaining high resolution vector maps which illustrate the flow patterns generated inside the EHD gas pump.

An EHD gas pump utilizing a ring/needle electrode

An electrohydrodynamic (EHD) gas pump, utilizing a ring/needle electrode, has been proposed and the effect of the ring electrode to the flow velocity and yield of flow generation of the EHD gas pump was investigated. The needle/ring is used as a corona discharge electrode and the mesh is used as the ion collecting electrode. It was observed that the proposed type of EHD gas pump can generate a higher flow velocity and yield of flow generation as compared with that from the same EHD gas pump without the ring electrode. As a result, a maximum flow velocity of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">W</sub> =4.54 m/s from the proposed EHD gas pump can be obtained at V=15.0 kV, which is 1.2 times higher than that of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">W</sub> =3.82 m/s of the same needle-to-mesh type EHD gas pump without the ring electrode. With the ring electrode, the yield of flow generation of Y <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">W</sub> =46.15 m/Ws can be obtained at V=11 kV, which is 2.5 times higher than that of the design without the ring electrode of Y <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">W</sub> =18.41 m/Ws. These enhancements, however, may be due to the effect of the ring electrode installed near the needle electrode.

Mechanism of electrohydrodynamically induced flow in a wire-non-parallel plate electrode type gas pump

An experimental investigation and one-dimensional modeling have been conducted to study the mechanism of net flow direction induced by electrohydrodynamic (EHD) forces in a wire-non-parallel plate electrode type EHD gas pump. The experiments were conducted with various different locations of corona wire electrode for negative and positive applied voltage from 0 to 14 kV at atmospheric pressure and room temperature, where air was used as the working fluid. A one-dimensional cross-sectional averaged model based on mass and momentum conservation as well as Poisson electric field and ion transport equations was also developed. The results show that the net flow direction of electrohydrodynamically induced gas flow in a wire-non-parallel plate electrode system significantly depends on the location of the corona wire electrode relative to the grounded electrode position. The effect of conversion angle of non-parallel plate electrode on the net flow direction and pressure drop also was investigated and discussed in detail.

Particle image velocimetry measurements of wire-non-parallel plate induction fan type electrohydrodynamic gas pump

2D and 3D PIV measurements were performed in wire-non-parallel plates type EHD gas pump. The velocity distribution of generated flow was measured for various discharge conditions. The flow rates of generated flow were calculated by integrating 3D velocity profiles. The results showed that the present EHD gas pump is capable to generate fl flow rates of several hundred cm3/s.

Flow characteristics of wire-rod type electrohydrodynamic gas pump under negative corona operations

The electrohydrodynamic (EHD) flow characteristics for a wire to rod type EHD gas pump have been experimentally investigated for pipe diameter sizes of 6.5, 10, and 20 mm. Experiments were conducted for dc negative applied voltage ranging from 0 to 24 kV applied between a corona wire with a diameter of 0.24 mm and a grounded rod electrode. The grounded rod electrode diameter is varied from 1.5 to 3.1 mm. The wire/rod electrode distance to pipe diameter ratio is varied from 0.63 to 1.16. The results show that gas flow rate increases with increasing EHD number or discharge current. A maximum of 40.1 L/min of gas flow rate is generated for a pipe diameter of 20 mm, with a grounding rod diameter electrode of 3.1 mm and corona wire to grounding rod electrode gap distant of 12.6 mm.