• Journal of the Korean institute of surface engineering
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• v.36 no.1
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• pp.69-73
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• 2003

The atmospheric pressure plasma is regarded as an effective method for surface treatments because it can reduce the period of process and doesn't need expensive vacuum apparatus. The performance of non-transferred plasma torches is significantly depended on jet flow characteristics out of the nozzle. In order to produce the high performance of a torch, the maximum discharge velocity near an annular gap in the torch should be maintained. Also, the compulsory swirl is being produced to gain the shape that can concentrate the plasma at the center of gas flow. In this work, the distribution of gas flow that goes out to atmosphere through a plenum chamber and nozzle is analyzed to evaluate the performance of atmospheric pressure plasma torch which can present the optimum design of the torch. Numerical analysis is carried out with various angles of an inlet flow velocity. Especially, three-dimensional model of the torch is investigated to estimate swirl effect. We also investigate the stabilization of plasma distribution. For analyzing the swirl in the plenum chamber and the flow distribution, FVM (finite volume method) and SIMPLE algorithm are used for solving the governing equations. The standard k-model is used for simulating the turbulence.

• Journal of the Korean Vacuum Society
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• v.22 no.3
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• pp.111-118
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• 2013

The influence of gas flow on the plasma generation in the atmospheric plasma jet is described with the theory of hydrodynamics. The plasma discharge is affected by the gas-flow streams with Reynolds number (Re) as well as the gas pressure with Bernoulli's theorem according to the gas flow rate inserted into the glass tube. The length of plasma column is varied with the flow types such as the laminar flow of Re<2,000 and the turbulent flow of Re>4,000 as it has been known in a general fluid experiments. In the laminar flow, the plasma column length is increased as the increase of flow rate. Since the pressure in the glass tube becomes low as the increase of flow velocity by the Bernoulli's theorem, the breakdown voltage of plasma discharge is reduced by the Paschen's law. Therefore, the plasma length is increased as the increasing flow rate with the fixed operation voltage. In the transition of laminar and turbulent flows, the plasma length is decreased. When the flow becomes turbulent as the flow rate is increasing, the plasma length becomes short and the discharge is shut down ultimately. In the discharge of laminar flow, the diameter of plasma beam exposed on the substrate surface is kept less than the glass diameter, since the gas flow is kept to the distinct distance from the nozzle of glass tube.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.369-372
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• 2009

A numerical analysis of the effect of plasma on flow characteristics in supersonic flow is studied. It is shown that change of direction and velocity magnitude of flow is appeared different in relative direction of plasma and fluid flow. The case of that direction of electrons, which are same with flow direction, the flow is accelerated, and the case of opposition, the flow is decelerated.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1736-1741
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• 2003

The characteristics plasma flow of an atmospheric plasma torch used for thermal plasma processing is studied. In general, it is produced by the arc-gas interactions between a cathode tip and an anode nozzle. The performance of non-transferred plasma torch is significantly dependent on jet flow characteristics out of the nozzle. In this work, the distribution of gas flow that goes out to the atmosphere through a plenum chamber and nozzle is analyzed to evaluate the performance of atmospheric plasma torch. Numerical analysis is carried out with various angles of an inlet flow which can create different swirl flow fields. Moreover, the size of plasma plume is experimentally depicted.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.6
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• pp.492-498
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• 2012

Characteristics of DBD(Dielectric Barrier Discharge) plasma actuator as design parameters were investigated for plasma flow control. Flow velocity and power consumption of the DBD plasma actuator were measured according to the design parameters such as discharge voltage and frequency, gap, width and length of electrode, and the thickness of dielectric barrier. The flow velocity and power consumption increased as the discharge voltage and frequency increased. As the electrode gap increased, the flow velocity increased with decreasing the power consumption, whereas high voltage was required for the plasma discharge. The flow velocity increased as the upper-electrode width decreased, and as the lower-electrode width increased at the constant power consumption. The performance of the DBD plasma actuator can be estimated at the given discharge and geometry conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.5
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• pp.587-593
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• 2004

In this paper, flow characteristics of plasma flow in a micro-tube were investigated experimentally using micro particle image velocimetry(micro-PIV). For comparison, the experiments were repeated for deionized(DI) wale. instead of plasma. Both velocity profiles of plasma and do-ionized water are well agreed with the theoretical velocity distribution of newtonian fluid. We also carried out generating plasma-in-oil droplet formation at a Y-junction microchannel. In order to clarify the hydrodynamic aspects involved in plasma droplet formation, Rhodamine-B were mixed with plasma only for visualization of plasma droplet. With oil as the continuous phase and plasma as the dispersed phase, plasma droplet can be generated in a continuous phase flow at a Y-junction. For given experimental parameters, regular-sized droplets are reproducibly formed at a uniform flow conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.10
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• pp.832-839
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• 2007

The geometry and dimensions of an expansion chamber are decisive factors in thermal puffer plasma chamber designs. Because they together dominate the temperature and speed at which the cooling gas from the chamber flows back through a flow channel to the arcing zone for the successful interruption of fault currents. In this study, we calculated the flow and mass transfer driven by arc plasma, and investigated the effects of a flow guide installed inside a thermal puffer plasma chamber. It is found that the existing cold gas of the chamber mixes with hot gases entrained from the arcing zone and is subjected to compression due to pressure build-up in the chamber. The pressure build-up with the flow guide is larger than that without due to a vortex which rotates clockwise around the chamber center. By the reverse pressure gradient, the mixing gas of the chamber flows back out for cooling down the residual plasma near current zero. In the case with the flow guide, the temperature just before current zero is lower than that without, and the Cu concentration with high electrical conductivity is also less than that without the flow guide.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.527-528
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• 2012

DBD (Dielectric Barrier Discharge) plasma actuator was designed for aerodynamic drag reduction using plasma flow control, and the drag reduction was measured by wind-tunnel tests using 2D test model. At the zero wind velocity, the plasma flow control had no effect on the drag reduction because the flow separation and surface friction drag were not occurred. At the wind velocity of 2m/s, 9.7% of drag was reduced by the flow separation control. The drag reduction decreased as the wind velocity increased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.433-436
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• 2011

The effect of plasma on flow characteristics in subsonic flow in backward-facing step is studied. The velocty of main flows are 0.5 m/s. DBD plasma is using for flow control. Stainless foil and polymide films are used as an electrode and dielectric material. The change of flow characteristics are shown by different of plasma generation region in fluid flow.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.2
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• pp.90-97
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• 2019

Sparkjet actuator, also known as plasma synthetic jet actuator (PSJA), is an active flow control device that has possibility of controling supersonic flow. This actuator utilizes arc plasma to deposit energy onto the gas inside the cavity to raise temperature and pressure. A change in the state of the fluid inside the cavity generates pressure waves and momentum jet, and they are exhausted through out the orifice exit and disturb external flow field. Since the cavity flow is affected by arc plasma, which is an equilibrium plasma and have generated equilibrium flow, the equilibrium state of air should be considered in order to analyze the flow of sparkjet actuator. In this study, numerical program for equilibrium flow was developed for the use of sparkjet actuator analysis. The developed program was validated by comparing the time - accurate jet front positions with the reference result. Then, impulse characteristics of the actuator in the atmospheric quiescent air were explained.