• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1459-1460
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• 2006

A new gas jet Z-pinch EUV light source having double gas jet electrodes has been developed. It has two nozzles and two diffusers. The EUV beam is collected from the side of pinch plasma, generated in between the inner nozzle and corresponding diffuser. A cylindrical shell of He gas curtain produced by the outer nozzle is specially designed for shielding the debris and suppressing the inner gas expansion. We have succeeded in generating EUV energy of 1.22 mJ/sr/2%BW/pulse at 13.5nm. The estimated dimension of EUV source is to be FWHM diameter of 0.07 mm and length of 0.34 mm, and FW 1/e2 diameter of 0.15 mm and length of 1.2 mm.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.796-799
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• 2007

In the bench scale test unit consisting of four commercial filter elements, the traces of the transient pressure around the nozzle and overpressure in the filter cavity were measured to estimate the effect of nozzle on pulse cleaning. For the given pulse cleaning system, the convergent nozzle displayed better performance than the straight one. The optimum ratio of outlet to inside diameter of convergent nozzle was determined, which minimized the pulse gas consumption and maximized the entrainment effect. The angle and height of nozzle convergent part was also optimum operational condition, which is meaningful to the industrial applying.

• Journal of Industrial Technology
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• v.20 no.B
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• pp.45-53
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• 2000

A numerical study is done on the thrust vector control using gaseous secondary injection in the rocket nozzle. A commercial code, PHOENICS, is used to simulate the rocket nozzle flow. A $45^{\circ}-15^{\circ}$ conical nozzle is adopted to do numerical experiments. The flow in a rocket nozzle is assumed a steady, compressible, viscous flow. The exhaust gas of the rocket motor is used as an injectant to control the thrust vector of rocket at the constant rate of secondary injection flow. The injection location which is on the wall of rocket is chosen as a primary numerical variable. Computational results say that if the injection position is too close to nozzle throat, the reflected shock occurs. On the other hand, the more mass flow rate of injection is needed to get enough side thrust when the injection position is moved too far from the throat.

• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.109-112
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• 2002

The supersonic jet discharging from a petal nozzle is known to enhance mixing effect with the surrounding gas because it produces strong longitudinal vortices due to the velocity difference from both the major and minor axes of petal nozzle. In the present study, the supersonic free jet discharging from the petal nozzle is investigated experimentally. The nozzles used are 4, 6, and 8 lobed petal nozzles with a design Mach number of 1.7, and the flow fields are compared with a circular nozzle with the same design Mach number. The pitot impact pressures are measured using a fine pilot probe. The flow fields are visualized using a Schlieren optical method. The results show that the petal nozzle has more increased supersonic length compared with the circular jet.

• Proceedings of the KWS Conference
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• 1999.10a
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• pp.146-149
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• 1999

To develope the high speed gas cutting tip, consists of 3 pieces, supersonic axisymmetric jets issuing from various kinds of nozzles with a throat diameter of a few milimeters were experimentally investigated. The nozzle inlet pressure was varied from 4 to 8 kgf/$\textrm{cm}^2$. The parameters in nozzle design were throat diameter, throat length, taper angle, outlet diameter. The total pressure variation was measured by the pilot tube, 0.5mm outer diameter, along the center of the free stream jet. Also color Shilieren system was used to visualize the flowfield.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.712-716
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• 2003

In the present study, the gas injection system based on air-water model was designed to investigate the behavior characteristics of bubbles injected into a ladle. The parameters such as gas volume fraction and bubble rise velocity were exprementally measured in a gas-liquid flow region. To measure gas volume fraction, an electo-conductivity probe was used and bubble rise velocity was obtained by a high speed CCD camera. Gas volume fraction was symmetric to the axis of nozzle secured on the bottom of a ladle. The bubble rise velocity was calculated for two different experimental conditions. That is, gas flow conditions were following two case: 1) Q = $0.63{\times}10^{-4}$ $m^{3}/s$, 2) $1.26{\times}10^{-4}$ $m^{3}/s$. As a gas injected into the liquid ladle, the liquid-phase region is circulated by bubbles' behavior. The bubble rise velocity was influenced of the circulation flow of liquid phase. As a result, the bubble rise velocity was appeared higher middle region of ladle than near the nozzle.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.4
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• pp.42-52
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• 1997

The basic principle of underwater ram-jet as a unique marine propulsion concept showing vary high cruise speed range(e. g. 80-100 knots) is the thrust production by the transfer of the potential energy of compressed gas to the operating liquid through kinetic mixing process. This paper is aimed to investigate the propulsive efficiency of the nozzle flow in underwater ram-jet at the speed of 80 knots for the buried type vessel. The basic assumption of the theoretical analysis is that mixture of water and air can be treated as incompressible gas. For an optimized nozzle configuration obtained from the performance analysis, preliminary data for performance evaluation are obtained and effects of nozzle inner wall friction, ambient temperature, ambient pressure, water density, gas velocity, bubble radius, flow velocity, diffuser area ratio, mass flow ratio and water velocity gradient are investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.204-207
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• 2003

This paper presents the electrical properties of PTFE (polytetrafluoroethylene) nozzle for circuit breaker. PTFE has been used widely as a nozzle material for circuit breaker. In the arcing environment in a circuit breaker, radiation is considered to be the major energy transport mechanism from the arc to the wall. The fraction of the radiation power is emitted out of the arc and reaches the nozzle wall, causing ablation at the surface and in the depth of the wall. The energy concentration in the material lead to the depolymerization and eventually lead to the generation of decomposed gas as well as some isolated carbon particles. The generation of the decomposed gas in the depth of the material causes inner explosion. The surface of nozzle becomes uneven. The flow of gas is not uniform due to the unevenness of the surface. Adding some fillers into PTFE is expected to be efficient for improving the endurability against radiation. In this experiment, three kinds of fillers that have endurance in the high temperature environment were added into PTFE. Dielectric constant, dissipation factor, electrical resistivity and dielectric strength of PTFE composites were investigated.

• Journal of ILASS-Korea
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• v.20 no.2
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• pp.82-87
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• 2015

A nozzle with vortex generator was used to develop the low pressure nozzle with high atomization performance and the nozzle atomized the liquid by centrifugal shear forces. In order to analyze the atomization characteristics, a shadowgraphy method was used and the measurement of droplet size was performed by using laser diffraction analyzer. The liquid injection pressure was fixed as 0.03 bar which is very low pressure and the gas injection pressures were changed from 0 bar to 2.0 bar. As a result, the breakup was achieved at the air injection pressure of 0.25 bar and over. The nozzle with the orifice diameter of 0.4 mm and the orifice gap of 0.25 mm presented small droplet diameters under 50 at the air injection pressure of 0.75 bar.

• Journal of ILASS-Korea
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• v.7 no.4
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• pp.1-8
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• 2002

This paper investigates the spray angle and the outline shape of the liquid sheet discharged from a simplex swirl nozzle. A theoretical model was proposed and the corresponding experimental data were presented for comparison. Axial and tangential velocities and thickness of the liquid sheet at the nozzle exit were also predicted. The liquid sheet thickness at nozzle exit, as well as the discharge coefficient, turned out to be a sole function of the swirl Reynolds number. However, the axial and tangential velocities at nozzle exit and the spray angle could not be expressed only with the swirl Reynolds number. The predicted outline shape and spray angle of the liquid sheet agreed reasonably with the measured data.