Flow Induced by a Two Stage Electrohydrodynamic Gas Pump in a Square Channel

In this study, forced convection enhancement in a square channel by a single stage electrohydrodynamic (EHD) gas pump is numerically examined. The EHD gas pump having three different sizes of grounded electrode configurations: 0.5-inch, 1-inch, and 2-inch wide respectively are investigated for their effectiveness in the enhancement of forced convection and pumping power requirement. The EHD gas pump with 28 emitting electrodes is evaluated for a wide range of operating voltages starting from 20 kV up to 28 kV. The influence of electric field on the flow and temperature fields is also examined for a wide range of Reynolds numbers. The three-dimensional governing equations for the flow and temperature fields are solved using the finite volume method. The Reynolds numbers (Re) considered in this study varies in a range between 100 and 2000. At Re = 100, a maximum increase of 55% in the average Nusselt number is achieved with an applied voltage of 28 kV. The overall effectiveness of the EHD gas pump in heat transfer enhancement is evaluated by the thermal hydraulic performance parameter, (Nu/Nu0)/(f/f0), which is always greater than unity. These results disclose that EHD technique has a great potential for many engineering applications, particularly for thermal management.

Flow characteristics of a two-stage electrohydrodynamic (EHD) gas pump in a circular tube have been experimentally investigated for two different sizes (61.8 and 127.8 mm in diameter). Each stage uses eight emitting electrodes flush mounted on the tube wall. Two electrode configurations, aligned and offset, with fixed spacing between electrodes have been considered in this study. The main objective of the study is to verify whether or not a two-stage EHD pump can sustain or even increase the volume flow rate produced by a single-stage pump over a greater tube length. To this end, electrodes at both stages are charged at the same voltages in positive polarity from 18 to 22 kV. Velocities are measured at three cross sections along the tube length and then integrated to obtain the volume flow rate. The velocity profile and volume flow rate delivered by the single top stage of the pump are compared with those produced by the two stages combined to give additional insight to the problem. The results obtained have important implications for practical applications of EHD gas pump.

EHD gas pump as a cooling device for electronic components in a horizontal channel

The performance of a two-stage electrohydro-dynamic (EHD) gas pump in a circular tube has been investigated for operating conditions in which each stage is charged at a different voltage. The main objective of the study is to examine the characteristics of resulting flow as well as the efficient use of energy in sustaining and improving the volume flow rate produced by a single-stage pump over a greater distance. To this end, two different sizes of tube are employed (61.8 mm and 127.8 mm in diameter). Each stage uses eight emitting electrodes flush mounted on the tube wall. In addition, two electrode configurations, aligned and offset, with fixed electrode spacing have been considered. The electrodes at both stages are charged at voltages in positive polarity from 18 kV to 22 kV. The velocity profile and volume flow rate delivered are compared with those produced by the same pump operating at even voltages to provide additional insight to the problem. The results thus obtained have important implications for practical use of EHD gas pump.

EHD gas pumping – A concise review of recent development

The effect of electrode orientation in an electrohydrodynamic (EHD) gas pump inside a square channel is experimentally examined for its effective use in thermal management. The two-stage gas pump with electrodes flush mounted on two parallel walls in each stage is powered by DC voltages ranging from 24 to 28 kV. In addition to the volume flow rate produced, the performance of the pump is evaluated using an energy efficiency factor, which is defined as the volume flow rate delivered by a unit power input. It is found that this parameter has a larger value for the EHD pump with aligned electrodes. However, the EHD pump with offset electrodes can produce more mixing of flow inside the channel, which may be more favorable for the application in thermal management. Most importantly, EHD gas pumps with either electrode configuration have a greater energy efficiency than conventional fans, and thus have a greater advantage for applications in the thermal management. This advantage is even more prominent when pumps are operated with uneven applied voltages.

In this paper, the flow field inside a square channel with a two-stage electrohydrodynamic (EHD) gas pump has been critically examined by experimental measurement and numerical simulation. The EHD gas pump with 28 emitting electrodes in each stage is tested for a wide range of operating voltages starting from the corona onset voltage up to 28 kV for further improvement in its performance over a single-stage one. It has been shown that the two-stage EHD gas pump can produce and sustain gas flows with a maximum velocity of 1.8 m/s. Its maximum performance of 36 L/s/W is better than that of conventional cooling fans used in personal computers. The implication for its application in thermal management and heat transfer enhancement has also been discussed.

Electrohydrodynamic (EHD) phenomena have been shown to enhance heat transfer in a variety of heat transport designs including capillary pumped loops for extraterrestrial nuclear applications. Previously, EHD enhancement has been shown to improve the heat transport of experimental CPLs. Further enhancement with the addition of EHD gas pumps to the vapour phase requires EHD gas pump phenomena and performance to be characterized with respect to gravity to determine the expected enhancement from this arrangement in zero and microgravity environments. In this paper an EHD gas pump is oriented with gravity (inverted), 90° to gravity (horizontal) and against gravity (vertical) to determine the effect gravitational and buoyancy forces have on the flow and heat transport of EHD gas pumps. The flow and temperature profiles of the pump at the outlet are presented to demonstrate the orientation effect gravity and buoyancy imposes on EHD gas pumps. The EHD number is calculated and presented. The paper determines that there is a noticeable orientation effect at lower applied voltages due to the heating effects causing recirculation in the flow being reduced with the aid of buoyancy forces. However, the effect is less noticeable at higher applied voltages due to the stronger EHD forces.

In recent years, functional fluidic and gas electrohydrodynamic (EHD) pumps have received considerable attention due to their remarkable features, such as simple structure, quiet operation, and energy-efficient utilization. EHD pumps can be applied in various industrial applications, including flow transfer, thermal management, and actuator drive. In this paper, the authors reviewed the literature surrounding functional fluidic and gas EHD pumps regarding the following aspects: the initial observation of the EHD effect, mathematical modeling, and the choice of pump structure, electrode configuration, and working medium. Based on the review, we present a summary of the development and latest research on EHD pumps. This paper provides a critical analysis of the current limitations of EHD pumps and identifies potential areas for future research. Additionally, the potential application of artificial intelligence in the field of EHD pumps is discussed in the context of its cross-disciplinary nature. Many reviews on EHD pumps focus on rigid pumps, and the contribution of this review is to summarize and analyze soft EHD pumps that have received less attention, thus reducing the knowledge gap.

Flow characteristics of dc wire-non-parallel plate electrohydrodynamic gas pumps

Electrohydrodynamic (EHD) pumps are a promising driving source for various fluid-driven systems owing to features such as simple structure and silent operation. The performance of EHD pumps depends on the properties of the working fluid, such as conductivity, viscosity, and permittivity. This implies that the tuning of these parameters in a working fluid can enhance the EHD performance. This study reports a method to modify the properties of a liquid for EHD pumps by mixing an additive. Specifically, dibutyl adipate (DBA) and polyvinyl chloride (PVC) are employed as the working fluid and the additive, respectively. The results show that when the concentration of PVC is 0.2%, the flow rate and pressure at applied voltage of 8 kV take highest value of 7.85 μL/s and 1.63 kPa, respectively. These values correspond to an improvement of 109% and 40% for the flow rate and pressure, respectively, compared to the pure DBA (PVC 0%). When the voltage is 10 kV, the flow rate of 10.95 μL/s and the pressure of 2.07 kPa are observed for DBA with PVC concentration of 0.2%. These values are more than five times higher than those observed for FC40 at the same voltage (2.02 μL/s and 0.32 kPa). The results also suggest that optimal conductivity and viscosity values exist for maximizing the EHD performance of a liquid. This demonstrates the validity of the proposed method for realizing high-performance EHD pumps by using additives in the working fluid.

Developing soft actuators has emerged as one of the most promising areas in robotics, with a growing demand for tunable lenses driven by the rapid advancements in intelligent mobile devices and cameras. Traditional mechanical lens systems are characterized by their heaviness, complexity, and rigidity. To address these limitations, this research introduces a novel approach: a dual‐chamber liquid lens actuated by an electrohydrodynamic (EHD) pump. The study involves the fabrication of a planar EHD pump, with an experimental investigation into the impact of electrode gap, electrode width, and electrode‐pair gap on the pump's pressure. Following the optimization of the EHD pump, a dual‐chamber lens is constructed, comprising two chambers, a rigid transparent plate, and two prestretched elastic membranes, which are connected to the EHD pump via tubes. Additionally, a mathematical model is developed to predict the focal length of the lens. Both experimental and theoretical analyses are conducted to explore the effects of the prestretch ratio of the elastic membranes and the radius ratio of the two chambers on focal length variation. The theoretical predictions of the focal length–voltage curves align closely with the experimental findings, providing validation for the proposed theoretical model.

The electrohydrodynamics (EHD) technique has shown promising results in enhancing heat transfer and mass transport. It has endless potential in industrial applications such as drying technology, design of evaporators, condensers, electrostatic precipitator, plasma actuator, and micropumps in microfluidic, chip-integrated cooling, and drug delivery systems. In recent years, a significant amount of research has been directed to design EHD micropumps as researchers realize their attractive features (e.g., no moving part, simple fabrication process) are most suitable in the aforementioned microelectro-mechanical systems (MEMS). This paper evaluates the performance of an EHD pump in a vertical square (4 × 4 inch) channel with a non-intrusive wire-electrode configuration. The voltage and current characteristics of the EHD pump are measured such that numerical simulations can be carried out. Measurements were taken from the corona threshold voltage to the occurrence of sparkover with a 1 kV increment. Due to the corona wind generated, the average volume flow rate in the channel was as high as 10 liter per second subjected to a voltage difference of 25 kV.

One of the most important problems in Mechanical Engineering is the determination of laminar boundary layer thickness over a flat plate. Integral solution and similarity solutions are two well‐known methods for calculation of boundary layer thickness. However, integral solution method is a computational cost‐effective method rather than the similarity solution method. Velocity and temperature profiles must be determined for the integral solution method. Velocity boundary layer thickness can be determined by the velocity profile whereas for determination of thermal boundary layer thickness both velocity and temperature profiles must be used. Available velocity profiles do not give an exact value for velocity boundary layer thickness, while the Nusselt number is affected by these profiles. In this study, a new velocity profile is proposed which gives an exact value for laminar boundary layer thickness on a flat plate. In addition, two temperature profiles are proposed that give the exact values of the Nusselt number over a flat plate for uniform temperature and uniform heat flux boundary conditions. The calculated constants in the velocity boundary layer thickness equation and the Nusselt relations are validated with the results of the similarity solution method. Excellent agreement between the results of the two methods is observed.

Designing and manufacturing actuators using soft materials are among the most important subjects for future robotics. In nature, animals made by soft tissues such as the octopus have attracted the attention of the robotics community in the last years. Suckers (or suction cups) are one of the most important and peculiar organs of the octopus body, giving it the ability to apply high forces on the external environment. The integration of suction cups in soft robots can enhance their ability to manipulate objects and interact with the environment similarly to what the octopus does. However, artificial suction cups are currently actuated using fluid pressure so most of them require external compressors, which will greatly increase the size of the soft robot. In this work, we proposed the use of the ElectroHydroDynamics (EHD) principle to actuate a suction cup. EHD is a fluidic phenomenon coupled with electrochemical reaction that can induce pressure through the application of a high-intensity electric field. We succeeded in developing a suction cup driven by EHD keeping the whole structure extremely simple, fabricated by using a 3D printer and a cutting plotter. We can control the adhesion of the suction cup by controlling the direction of the fluidic flow in our EHD pump. Thanks to a symmetrical arrangement of the electrodes, composed by plates parallel to the direction of the channel, we can change the direction of the flow by changing the sign of the applied voltage. We obtained the pressure of 643 Pa in one unit of EHD pump and pressure of 1428 Pa in five units of EHD pump applying 6 kV. The suction cup actuator was able to hold and release a 2.86 g piece of paper. We propose the soft actuator driven by the EHD pump, and expand the possibility to miniaturize the size of soft robots.