대항류형 보텍스 튜브의 길이 및 노즐의 위치 변화에 따른 온도 분리 특성에 관한 실험적 연구

전운학,황승식 국민대학교 생산기술연구소 2004 공학기술논문집 Vol.27 No.-

The aim of this study is to provide fundamental informations that make it possible to use a cool stream and a hot stream simultaneously. To achieve the aim, we changed the pressure of compressed air that flows into a tube, the length of tube in a hot stream exits, the position of nozzle that inject compressed air into a tube and the mass flow rate ratio. And in each case, we measured the temperature of a cold stream and a hot stream in each exit of a tube. From the study, following conclusive remarks can be made. Generally as inlet pressure increases, temperature difference between inlet air and outlet air in cold and hot stream increases. When we analyze energy separation effect according to the length change of vortex tube, maximum cold and hot air temperature difference is measured that the ratio of tube length to tube diameter is 35, 20. We find a length of vortex tube that brings effect of the energy seperation better. And as inlet nozzle keep away from the orifice that a cold stream exits by degrees, energy seperation effect is better.

Ranque-Hilsch tube의 입구 형상 변화에 따른 고온특성에 관한 실험적 연구

전운학,황승식 국민대학교 생산기술연구소 2003 공학기술논문집 Vol.26 No.-

Vortex-tube is a cylindrical device that separates a flow of compressed air into a hot stream and a cold stream. Compressed air flowing tangentially into a tube, it spirals down the tube and produces two flows. Vortex-tube uses nothing but compressed air as a power source. Vortex-tube is being expected as a pro-environment cooling and heating system. The aim of this study is to provide fundamental informations that make it possible to use a cool stream and a hot stream simultaneously and High temperature characteristics especially. To achieve the aim, we changed the inner diameter of orifice that a cold stream exits, the number of nozzles that inject compressed air into a tube, the form of nozzle arrangement and the mass flow rate ratio. And in each case, we measured the temperature of a cold stream and a hot stream in each exit of a tube. Also we measured the axial temperature distribution in surface of a tube. From the study, following conclusive remarks can be made. First, the inner diameter of orifice have an effect on the characteristics of high temperature. Second, when orifice inner diameter is 10mm, range of high temperature is 80% of whole tube surface. Third, when we analyze energy separation effect according to the change of nozzle shape, the high temperature characteristics is affected by the number of nozzles

Ranque-Hilsch 볼텍스 튜브에서의 에너지 分離에 관한 實驗的 硏究

전운학,황승식 국민대학교 생산기술연구소 2002 공학기술논문집 Vol.25 No.-

The aim of this investigation is to provide the fundamental data of the geometric condition which improve the effect of the energy separation. The effect of the energy separation is better, the temperature difference is larger. In this investigation, the inner diameter of the vortex tube is 20mm and the ratio of the length to the inner diameter is 20. The cone angle of the throttle valve is 60˚and 90˚. Varying the inner diameter of the nozzle and the orifice, the experiment is carried out. From the experiment, the following conclusive remarks can be proposed. When the inner diameter of the nozzle increases, we can observe that the energy separation effect is better. And we find the geometry condition of the orifice that makes the energy separation effect better. And when we use the 60˚cone, the energy separation effect is better.

곡관내 자성유체 PLUG의 진동특성

전운학(U. H. Chun),이행남(H. N. Lee) 한국자동차공학회 1995 한국 자동차공학회논문집 Vol.3 No.3

The aim of the present study is to provide fundamental informations for the development of magneticfluid actuator. To achieve the aim, oscillation characteristics of the magneticfluid plug are investigated by experiment for the various length and position of the magneticfluid plug and the frequency of magnetic field. The oscillation characteristics are obtained. Amplitude, natural frequency, phase shift and damping ratio, are compared with theoretical values. From the study, the following conclusive remarks can be made. The experimental equation for the magnetic field is obtained. The critical magneticfluid length exists and its value is about 70mm. The range of the<br/> damping ratio and fluid loss coefficient obtained by experiment are 0.1~0.2 and 30~100,<br/> respectively. Comparison between experimental and theoretical results of oscillation characteristics shows good agreement in the high frequency range. Meanwhile, in the low frequency range, there appears little discrepancies(5% in the frequency and amplitude and 10% in phase difference and damping ratio) with each other.

[論文] 돌연 확대관에서 비뉴우튼 유체의 재접착 실험

전운학(U. H. Chun),이행남(H. N. Lee) 한국자동차공학회 1993 오토저널 Vol.15 No.1

The reattachment lengths of the Non-Newtonian fluid are investigated in the sudden expansion pipes whose ratios are 2.316 and 3.368, and the range of the Reynolds numbers is 100- 30000. The reattachment lengths for the viscoelastic fluid in the laminar flow region are found to be much shorter than those of the Newtonian fluid. and decrease significantly with the increase of the concentration of viscoelastic fluid at the same Reynolds number. In the turbulent flow region, the reattachment length for the viscoelastic fluid is two or three times longer than those of water, and gradually increases with the increase of the concentration of viscoelastic fluid.

스프링-質量 系에서 磁性 流體의 振動 特性에 關한 硏究

전운학(U.H.Chun),이봉규(B.K.Lee),홍상록(S.R.Hong) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_2

Under magnetism, as the magnetic fluid is being itself magnetized, increase the apparent viscosity because of its body force and has the magnetic characteristics in response to magnetism, the magnetic fluid is getting attention in various field.<br/> The magnetic fluid has the fluidity, which is a special characteristic of fluid and the magnetism, which is a special one of solid. Using this characteristics, this study has been proceeded to show the basic data for developing of a viscous damper with magnetism fluid as hydraulic fluid.<br/> Experimental study shows that the application of magnetic field is effective reducing the resonance characteristic of the spring-mass system.<br/>

[구조강도부문] 대향류형 보텍스 튜브에서의 에너지 분리에 관한 실험적 연구

전운학(Unhack Chun),황승식(Seungsik Hwang) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

The aim of this study is to provide fundamental informations that make it possible to use a cool stream and a hot stream simultaneously. We changed the pressure of compressed air that knows into a tube, the inner diameter of orifice that a cold stream exits, and the mass now rate ratio. And in each case, we measured the temperature of a cold stream and a hot stream in each exit of a tube. Also we measured the axial temperature distribution and the radial temperature distribution in internal space of a tube. From the study, following conclusive remarks can be made. Average flow rate that flows into a tube is in proportion to square root of inlet pressure. As inlet pressure increases axial and radial temperature distribution in the inner space of vortex-tube increase. As mass flow rate ratio change, separation point moves.

磁性 流體를 利用한 1自由度 系의 共振減少에 關한 實驗的硏究

전운학(C.H.Chun),이봉규(B.K.Lee),황승식(S.S.Hwang),이희상(H.S.Lee),김중(J.Kim) 한국자동차공학회 1999 한국 자동차공학회논문집 Vol.7 No.9

Under magnetism, as the magneticfluid is being itself magnetized, increase the apparent viscosity because of its body force and has the magnetic characteristics in response to magnetism, the magnetic fluid is getting attention in various field.<br/> The magnetic fluid has the fluidity, which is a special characteristics of fluid and the magnetism, which is a special one of solid. Using this characteristics, this study has been proceeded to show the basic data for developing of a viscous damper with magnetism fluid as hydraulic fluid.<br/> Experimental study shows that the application of magnetic field is effective reducing the resonance characteristics of the spring-mass system.

입자크기와 노즐형상이 입자유동특성에 미치는 영향

전운학(U. H. Chun),김종철(J. C. Kim),황승식(S. S. Hwang) 한국자동차공학회 1998 한국 자동차공학회논문집 Vol.6 No.5

The flow structure of particles for two different injectors has been investigated experi-mentally by means of a Phase Doppler Particle Analyzer(PDP A). Two injectors used in the present study are the pipe and contraction nozzle. Particles of 0.8 ㎛, 30 ㎛, 60 ㎛, and 100 ㎛diameter were injected with a constant mass loading ratio of 0.01 and a Reynolds number of 13200. The initial mean velocity and turbulent intensity of particle are strongly influenced by the particle size and the injector geometry. The flow angles of particle at nozzle exit are sensitive to the particle size rather than the injector geometry.<br/>

[論文] 유동과 열전달 특성을 고려한 수평 전자회로 기판의 설계조건에 관한 수치적 연구

전운학(U.H.Chun),이행남(H.N.Lee),김현모(H.M.Kim) 한국자동차공학회 1992 오토저널 Vol.14 No.2

Flow and heat transfer characteristics in a horizontal electronic circuit board are studied numerically. The board has the arrays of heated blocks and the spaces between the plates and blocks are changed.<br/> Air is used as cooling fluid, of which prandtl number is 0.7. The velocity distributions, temperature distributions, Nusselt numbers and dimensionless friction factors are obtained on the spaces between the plates and the blocks, for the cases of Rayleigh number, 0 and 1O^5. When Rayleigh number is so large, such as 10^5, that the effect of bouyancy is not negligible, fluid friction and heat transfer is increased more than those of forced convection. This may be caused by the generation of secondary flow on the cross section of primary flow. The effect of bouyancy is of the most efficient, when the space of blocks is about block-width and the space of plates is about 1.7 times of block-height.