Comparison of Turbulence Models for a Free-burning High-intensity Argon Arc

김윤제,이종철 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.9

Free-burning arcs where the work piece acts as an anode are frequently used for a number of industrial applications. Our investigation was concerned with developing a capability to model free-burning high-intensity argon arcs and enhancing the accuracy of numerical results according to a comparative study of turbulence models. For the arc modeling involved complicated interactions between the flow and electromagnetic fields, we modified the Navier-Stokes equations to take into account the radiation transport, the electrical power input and the electromagnetic driving forces with the relevant Maxwell equations. For the turbulence modeling, which is critical to the arc edges due to a steep temperature gradient between the arc column and the surrounding gas, zero- and twoequation eddy-viscosity models were used. The major arc parameters of temperature, axial velocity,electric potential difference and pressure-rise from ambient atmospheric pressure were summarized under laminar and turbulent conditions. It was found that the standard k-ε model modified to take into account the effect of a steep temperature gradient at the edge of free-burning arcs could predict reasonable temperature profiles better than the cases with the assumption of laminar flow and Prandtl’s mixing length model used for switching arcs.

Study on a plasma thermal oxidizer using gliding arc plasma assisted LPG combustion

Yong Wook Shin,Geon Woo Yang,Se Min Chun,Yong Cheol Hong 한국진공학회 2021 한국진공학회 학술발표회초록집 Vol.2021 No.2

Recently, interest in plasma assisted combustion to improve the thermal efficiency of traditional combustion technologies is increasing. In this regard, we studied a plasma thermal oxidizer (PTO) using LPG combustion assisted by gliding arc plasma. Combustion characteristics according to applied power, fuel injection amount, or fuel injection location were analyzed through flame temperature and gas analysis. Also we compared to traditional LPG combustion. Finally, PTO was applied to purify the odor gas of a large flow rate (~2N^-3/min) and the reduction of odor components was verified.

0.4 MW급 플라즈마 풍동을 이용한 우주용 내열재료의 삭마 시험

오필용(Philyong Oh),최정철(Jung Chul Choi),문세연(Se Youn Moon),홍봉근(Bong Guen Hong) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.5

우주비행체의 지구 재진입시 고엔탈피 압축성 유동에 의한 공력 마찰로 인해 비행체는 표면으로부터 10 MW/㎡ 이상의 열유속이 발생한다. 이로 인한 우주용 내열재료의 평가가 필요하며, 열차폐체는 비행시험에 사용 되기전 지상에서의 성능시험이 필수적으로 요구된다. 고엔탈피 플라즈마 풍동은 초음속 비행과 우주 비행체의 지구 재진입 조건 등 극한 환경의 모사가 가능하므로 열차폐체 평가 및 고온재료의 성능시험에 적용할 수 있다. 고온삭마 재료 중 탄소섬유강화 복합재 [4-5] 는 강한 산화 저항성과 높은 열기계적 성능이 우수해 우주용 내열재료로 사용된다. 극한 공력가열에 노출되는 우주용 내열재료의 평가를 위해 전북대학교 고온플라즈마응용연구센터에 구축된 0.4 MW급 분절형 아크 히터 플라즈마 토치를 이용하여 내열 삭마시험을 하였다. 분절형 아크 히터 풍동은 초음속의 고온 플라즈마 유동을 통해 내열재료의 삭마 거동을 살펴보았으며, 시편의 노출 시간, 표면 온도, 표면 침식율, 질량 감소율 등을 관찰하였다. 아크 플라즈마 풍동의 열유속은 5 ~ 10 MW/㎡ , 속도는 마하 3의 조건에서 실험하였다. Space vehicles reentering the earth"s atmosphere at high speed face a high enthalpy supersonic plasma flow induced by aerodynamic heating of the vehicle"s surface [1-3], which can transfer a heat flux above 10 W/m2 to a vehicle"s surface, necessitating the development of reliable thermal protection systems (TPS). A segmented arc plasma torch was designed to produce a supersonic plasma flow with enthalpy above 13 MJ/kg at a velocity of Mach 3. With flow rate of the gas in 16 g/s and the 195 input current in, we investigate evaluation of Heat Shield Materials for Aerospace Applications using a 0.4 MW class segmented arc plasma.

0.4 MW 급 아크가열 플라즈마 풍동의 성능특성

오필용(Philyong Oh),Rajesh Kumar Chinnaraj,홍성민(Seong Min Hong),신의섭(Eui Sup Shin),최성만(Seong Man Choi) 한국추진공학회 2018 한국추진공학회지 Vol.22 No.5

Thermal protection materials (TPMs) are very crucial for the survival of any re-entry space vehicles. One of the systems used for rigorous validation of TPMs is an enhanced Huel type segmented arc-heated plasma wind tunnel. A 0.4 MW class arc-heated plasma wind tunnel has been constructed at Chonbuk National University which is capable of producing high enthalpy supersonic flow. In this paper we have studied the characteristics of plasma flow according to power and mass flow parameters.

열팽창 파퍼식 가스차단기 차단설계를 위한 비정상 아크 플라즈마 유동해석

이종철(Jong-Chul Lee),김윤제(Youn J. Kim) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5

During the last ten years the new interruption techniques, which use the arc energy itself to increase the pressure inside a chamber by the PTFE nozzle ablation, have displaced the puffer circuit breakers due to reduced driving forces and better maintainability. In this paper, we have investigated the flow characteristics inside a thermal puffer type gas circuit breaker by solving the Navier-Stokes equations coupled with Maxwell's equations for considering all instabilities effects such as turbulence and Lorentz forces by transient arc plasmas. These relative inexpensive computer simulations might help the engineer research and design the new interrupter in order to downscale and uprating the GIS integral.

Research Articles : Hydrogen-rich Gas Production from Propane using Plasma-assisted Reforming

( Young Nam Chun ),( Sun Il Kim ) 한국공업화학회 2006 Journal of Industrial and Engineering Chemistry Vol.12 No.4

모사 부식 환경에서 플라즈마 아크용사에 의한 Al 코팅의 부식특성에 관한 실험적 연구

정화랑 ( Jeong¸ Hwa-rang ) 한국건축시공학회 2023 한국건축시공학회지 Vol.23 No.5

건설산업에서 사용되는 구조용 강재의 부식은 산업화로 인해 많은 공격적인 이온이 내포된 대기 환경에서 증가추세에 있다. 따라서 본 연구에서는 아크 및 플라즈마 아크용사로 Al 코팅을 용착하여 Cl^-와 CO₃ ^2-같은 공격적인 이온을 다량 함유한 Society of Automotive Engineering(SAE) J2334 용액의 모사대기환경에서 그 효과를 비교하였다. 다양한 분석기법으로 코팅 특성과 부식 메커니즘을 고찰하였다. 플라즈마 아크용사로 용착된 Al 코팅은 밀도 있고 균일하면 층층이 적층이 잘 되었고 높은 부착력이 나타났다. 이 공법으로 용착된 Al 코팅을 SAE J2334 용액에 기간별로 침지하여 측정한 개회로전위(OCP)는 아크용사로 용착된 Al 코팅보다 더 양전성(electropositive)한 값을 보여주었다. 플라즈마 아크용사는 총 임피던스가 아크용사보다 높게 나타났다. SAE J2334 용액에 23일 침지하였을 때 플라즈마 아크용사 Al 코팅의 부식속도는 아크용사에 비해 20% 감소하였다. The corrosion of structural steel used in the construction industry is increasing due to the industrialization where many aggressive ions released in the atmosphere. Therefore, in the present study Al coating was deposited by arc and plasma arc thermal spray process and compared their effectiveness in simulated weathering condition i.e. Society of Automotive Engineers(SAE) J2334 solution which mostly contain Cl^- and CO₃ ^2- ions. Different analytical techniques have been used to characterize the coating and draw the corrosion mechanism. The Al coating deposited by plasma arc thermal spray process exhibited uniform, dense and layer by layer deposition resulting higher bond adhesion values. The open circuit potential(OCP) of Al coating deposited this process is exhibited more electropositive values than arc thermal spray process in SAE J2334 solution with immersion periods. The total impedance of plasma arc thermal spray process exhibited higher than arc thermal spray process. The corrosion rate of the plasma arc thermal sprayed Al coating is reduced by 20% compared to arc thermal spray process after 23 days of immersion in SAE J2334 solution.

3.5% NaCl에서 Arc Thermal and Plasma Arc Spray 공법이 적용된 Al- Zn 코팅 강재의 내 식 성능 평가에 관한 연구

잔낫 ( Adnin Raihana Jannat ),이한승 ( Lee¸ Han-seung ) 한국건축시공학회 2021 한국건축시공학회 학술발표대회 논문집 Vol.21 No.2

In the present study, Al-Zn coating was deposited by Arc thermal (AT) and plasma arc thermal (PAT) spray processes, and their corrosion characteristics were studied in 3.5% NaCl through electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM) and mechanical tests. The bond adhesion result showed that plasma arc sprayed coating had a higher value attributed to compact, dense, and less porous coating compared to arc thermal spray coating which contains defects/pores and uneven morphology as revealed by scanning electron microscope analysis. Electrochemical results revealed that the plasma arc sprayed coating had a high polarization resistance at early stage of immersion, suggesting its excellent corrosion protection performance.

Effects of Operating Condition on the 2-dimensional Temperature and Velocity Distributions of a Thermal Plasma Jet in a Segmented Arc Heater

Byeong-Il Min,Juyoung Ko,Sooseok Choi,Tae-Hee Kim 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.5

A segmented arc heater with an input power of 2.5 MW for thermal protection studies of a re-entry vehicle was numerically simulated to determine its appropriate operating conditions. A self-developed magnetohydrodynamics code was used to analyze the 2-dimensional characteristics of the thermal plasma jet in the segmented arc heater. Operating ranges of the air ow rate and the arc current were from 20 to 60 g/s and from 400 to 800 A, respectively. Although the velocity of the thermal plasma jet and the input power were increased by increasing the air ow rate, the plasma enthalpy, which is proportional to the temperature, was decreased at a high air ow rate because of the cooling effect. On the other hand, an increase in the arc current had the positive effect of increasing the plasma temperature. As a result, the target enthalpy of over than 20 MJ/kg was achieved for an air ow rate of 40 g/s and an arc current above 600 A.

연성해석을 통한 열파퍼 플라즈마 챔버의 아크현상 이력에 관한 연구

이종철(Jong Chul Lee),허중식(Joong Sik Heo),김윤제(Youn Jea Kim) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5

The coupled simulation is performed to find out the interaction of arc plasmas with surrounding materials in a thermal puffer plasma chamber. In order to be more realistic, PTFE nozzle ablation and Cu electrode evaporation, which are caused by high temperature of arc plasmas, are considered together. Pressure rise and temperature inside the chamber generated during the whole arcing history are investigated with the applied currents. It is very important to define how thermal flow and mass transfer are processing between the arc plasma and surrounding materials for further understanding complex physics inside the chamber. It is concluded that the result might be very useful to understand the mechanism happened inside and to design thermal puffer plasma chambers, but further experimental studies are required to verify the results for the more practical applications.