• Title/Summary/Keyword: Nozzle Pressure

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Optimal Design of Clearance in Fuel Injection Pump (연료분사펌프의 최적 간극 설계)

  • Hong, Sung-Ho;Lee, Bora;Cho, Yongjoo;Park, Jong Kuk
    • Tribology and Lubricants
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    • v.31 no.4
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    • pp.148-156
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    • 2015
  • In the study, a design process for ensuring optimal clearance in a fuel injection pump(FIP) is suggested. Structure analysis and hydrodynamic lubrication analysis are performed to determine the optimal clearance. The FIP is simulated using Hypermesh, Abaqus 6.12 to evaluate the reduction of clearance when the maximum supply pressure is applied. The reduction in clearance is caused by the difference in the deformations between the barrel and plunger. When the deformation of the plunger is larger than that of the barrel, a reduction in clearance at the head part occurs. On the other hand, the maximum clearance reduction equals the maximum deformation in the stem part, because the deformation of barrel does not occur in this region. The clearance of FIP should be designed to be larger than maximum reduction of clearance in order to avoid contact between the plunger and barrel. In addition, the two-dimensional Reynolds equation is used to evaluate lubrication characteristics with variations of viscosity, clearance and nozzle for a laminar, incompressible, unsteady state flow. The equation is discretized using the finite difference method. The lubrication characteristics of FIP are investigated by comparing film parameter, which is the ratio of the minimum film thickness and surface roughness. The optimal clearance of FIP is to be designed by considering the maximum reduction in clearance, lubrication characteristics, machining limits and tolerance of clearance.

Solid Circulation Characteristics in a 3 kW Chemical-looping Combustor (3 kW급 매체순환식 가스연소기의 고체순환특성)

  • Ryu, Ho-Jung;Park, Jaehyeon;Kim, Hong-Ki;Park, Moon-Hee
    • Korean Chemical Engineering Research
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    • v.46 no.6
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    • pp.1057-1062
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    • 2008
  • To overcome disadvantages of conventional two interconnected fluidized beds system, a novel two-interconnected fluidized bed process has been adopted to 3kW chemical-looping combustor. This system has two bubbling beds, solid injection nozzles, solid conveying lines, and downcomers. In this study, effects of operating variables such as gas velocity through the solid injection nozzle, fluidizing velocity, solid height, geometry of solid intake hole, bed temperature on solid circulation rate have been investigated in a 3kW chemical-looping combustor. The solid circulation rate increased as the solid height and the opening area of solid intake holes increased. The effect of the fluidizing velocity and the bed temperature were negligible. Moreover, long-term operation of continuous solid circulation up to 50 hours has been performed to check feasibility of stable operation. The pressure drop profiles in the bubbling beds and the downcomers were maintained steadily and solid circulation was smooth and stable.

Strain-based plastic instability acceptance criteria for ferritic steel safety class 1 nuclear components under level D service loads

  • Kim, Ji-Su;Lee, Han-Sang;Kim, Jong-Sung;Kim, Yun-Jae;Kim, Jin-Won
    • Nuclear Engineering and Technology
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    • v.47 no.3
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    • pp.340-350
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    • 2015
  • This paper proposes strain-based acceptance criteria for assessing plastic instability of the safety class 1 nuclear components made of ferritic steel during level D service loads. The strain-based criteria were proposed with two approaches: (1) a section average approach and (2) a critical location approach. Both approaches were based on the damage initiation point corresponding to the maximum load-carrying capability point instead of the fracture point via tensile tests and finite element analysis (FEA) for the notched specimen under uni-axial tensile loading. The two proposed criteria were reviewed from the viewpoint of design practice and philosophy to select a more appropriate criterion. As a result of the review, it was found that the section average approach is more appropriate than the critical location approach from the viewpoint of design practice and philosophy. Finally, the criterion based on the section average approach was applied to a simplified reactor pressure vessel (RPV) outlet nozzle subject to SSE loads. The application shows that the strain-based acceptance criteria can consider cumulative damages caused by the sequential loads unlike the stress-based acceptance criteria and can reduce the overconservatism of the stress-based acceptance criteria, which often occurs for level D service loads.

Microscopic Evaluation and Analysis on the Tensile Strength of Hybridized Reinforcement Filament Yarns by the Commingling Process

  • Herath, Chathura Nalendra;Kang, Bok-Choon;Hwang, Beong-Bok;Min, Kyung-Ho;Seo, Jung-Min;Lee, In-Chul;Ruchiranga, Jayasekara Vishara;Lim, Joong-Yeon
    • Advanced Composite Materials
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    • v.17 no.3
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    • pp.225-233
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    • 2008
  • The analysis in this paper is focused on the pattern of mixing of filaments over a cross-section of hybrid yarns according to different combinations of reinforcement and matrix filament yarns through microscopic view. The volume content of filament in hybrid yarn cross-section was maintained at 50% for both reinforcement and matrix, and the hybrid yarns count at 600 tex throughout the experiments. It was observed from the experiments that diameters of reinforcement and matrix filaments have strong effects particularly on the pattern of mixing of filaments over a cross-section of hybrid yarns such that the hybrid yarns with more or less equal diameters of reinforcement and matrix filaments showed considerably even distributions over the hybrid yarn cross-section. This paper also investigates the possibility of hybridizing carbon/aramid, carbon/glass and aramid/glass matrices through the commingling process. In the experiment, several process parameters were selected and they include pressure, yarn oversupply-rate and different nozzle types. As a result of these experiments, it was concluded that the hybridized materials show better performance than individual reinforced filament yarns in terms of mechanical properties. For small tensile forces, the carbon/glass/matrix combination turned out to be good enough for general purpose applications.

Linear Stability Analysis for Combustion Instability in Solid Propellant Rocket (고체추진 로켓의 선형 안정성 요소에 대한 연구)

  • Kim, Hakchul;Kim, Junseong;Moon, Heejang;Sung, Honggye;Lee, Hunki;Ohm, Wonsuk;Lee, Dohyung
    • Journal of the Korean Society of Propulsion Engineers
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    • v.17 no.5
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    • pp.27-36
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    • 2013
  • Linear stability analysis for combustion instability within a cylindrical port of solid rocket motor has been conducted. The analysis of acoustic energy has been performed by a commercial COMSOL code to obtain the mode function associated to each acoustic mode prior to the calculation of stability alpha. An instability diagnosis based on the linear stability analysis of Culick is performed where special interests have been focused on 5 stability factors(alpha) such as pressure coupling, nozzle damping, particle damping and additionally, flow turning effect and viscous damping to take into account the flow and viscosity effect near the fuel surface. The instability decay characteristics depending on the particle size is also analyzed.

Fine Dispensing Process of High Viscosity Phosphor for Repairing Application of White LED (백색 LED 보정 공정 적용을 위한 고점도 형광체 미세 정량토출 공정)

  • Yang, Bong Su;Yang, Young Jin;Kim, Hyung Chan;Ko, Jeong Beom;Cho, Kyung Ho;Doh, Yang Hoi
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.25 no.2
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    • pp.124-131
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    • 2016
  • Several research works for finding and optimizing the methods of dispensing high viscosity phosphor used in the fabrication of white LED's are currently in progress. High viscosity phosphor dispensing with a high accuracy is crucial because the dispensing rate and uniformity directly affect parameters such as the CIE chromaticity diagram, color temperature and luminous flux of white LED's. This study presents a novel method of dispensing high viscosity phosphor using electrohydrodynamic printing. The dispensing rate was optimized less than 0.01 mg phosphor using experiments and optimizing the process parameters including the standoff distance from the nozzle to the substrate, ink supply pressure, and multi-step pulsed waveform magnitude ratio. The dispensing rate was measured by dispensing 20 dots using drop-on-demand with the optimized parameters, and the experiments were repeated 10 times to maximize the data accuracy. The average dispensing rate that can be reliably used for high viscosity phosphor dispensing was 0.0052 mg.

PIV Measurement and Color Schlieren Observation of Supersonic Jets (PIV 및 컬러 쉴리렌 기법을 이용한 초음속 제트 관측)

  • Lee, Jae Hyeok;Zhang, Guang;Kim, Tae Ho;Kim, Heuy Dong
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.604-605
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    • 2017
  • The present work aims at visualization of the supersonic air jet flows discharged from C-D nozzles. In the present experiments, Prticle Image Velocimetry (PIV) was employed to specify the jet flow field quantitatively, and a color Schlieren optical method was applied to observe the same jets qualitatively. The $0.5{\mu}s$ duration of spark light source was used for Schlieren and it can be controled as $0.5{\mu}s$, $1{\mu}s$, $2{\mu}s$ and focusing mode. The convergent-divergent nozzles were used to generate the jet flow with the design Mach number of 2.0, 2.2. Nozzle pressure ratios (NPRs) were varied from 5 to 8. A good comparison of the jet size and shock location from the Schlieren images with the PIV quantitative values is obtained. The obtained images clearly showed the major features of the under-expanded jet, over-expanded jet, sound wave, turbulent eddies and so on.

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Numerical Investigation of the Effect of flow Passage Variation on the Projection Distance of the Foam Monitor (유로형상변경에 따른 폼 모니터 분사거리 변화의 수치적 해석)

  • Lee, Young-Hoon;RYU, Young-Chun;Seong, Jeong-Hyun;Park, Young-Chul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.1
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    • pp.244-251
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    • 2016
  • In this study, the relationship between flow characteristics and projection distance, depending on the shape was examined. A numerical investigation technique for fluid analysis of a foam monitor was developed for the prediction, comparison and validation of the actual injection performance. The foam monitor changes the flow pattern of fluid flow according to the shape, The fluid losses were calculated from the numerical investigation affecting the projection distance. The basic form of foam monitor was used as a designed shape in N. The modified model used the length increase model of the flow path, and straight line of the model. The inlet pressure was 6.5bar. The results showed that the length increase model of the flow path and straight line of the model in the nozzle projection distance had improved. The results comparing the error rates projection performance were well matched to the 7.43% obtained from the validity test of the analysis method.

Development of water cropping machine for slab pattern processing (석판재용 물다듬 패턴무늬 가공 전용기 개발)

  • Kim, Kyoung-Chul;Ko, Min-Hyuc;Kim, Jong-Tae;Lee, Ji-Su;Ryuh, Beom-Sahng
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.9
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    • pp.4130-4135
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    • 2013
  • This paper is a special-purpose machine studies for processing various patterns on the surface of the stone. We have developed a special-purpose machine that can be applied in various patterns upon the surface treatment of the stone with the water jet. The special-purpose machine is Configured of Transfer mechanism, motion controller, multi-nozzle mechanism, ultra high pressure water control system and S/W. We conducted a performance evaluation experiments of the pattern. We have developed a special-purpose machine with a precision of machining error ${\pm}0.5mm$ and pattern processing of various types.

Surface Morphology and Optical Properties of Aluminosilicate Glass Manufactured by Physical and Chemical Etching Process (물리·화학적 혼합 식각 공정에 의해 제조된 알루미노실리케이트 유리의 표면 형상과 광학 특성)

  • Kim, Namhyuk;Sohn, Jeongil;Kim, Gwangsoo
    • Korean Journal of Materials Research
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    • v.27 no.9
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    • pp.501-506
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    • 2017
  • Surface morphology and optical properties such as transmittance and haze effect of glass etched by physical and chemical etching processes were investigated. The physical etching process was carried out by pen type sandblasting process with $15{\sim}20{\mu}m$ dia. of $Al_2O_3$ media; the chemical etching process was conducted using HF-based mixed etchant. Sandblasting was performed in terms of variables such as the distance of 8 cm between the gun nozzle and the glass substrate, the fixed air pressure of 0.5bar, and the constant speed control of the specimen stage. The chemical etching process was conducted with mixed etching solution prepared by combination of BHF (Buffered Hydrofluoric Acid), HCl, and distilled water. The morphology of the glass surface after sandblasting process displayed sharp collision vestiges with nonuniform shapes that could initiate fractures. The haze values of the sandblasted glass were quantitatively acceptable. However, based on visual observation, the desirable Anti-Glare effect was not achieved. On the other hand, irregularly shaped and sharp vestiges transformed into enlarged and smooth micro-spherical craters with the subsequent chemical etching process. The curvature of the spherical crater increased distinctly by 60 minutes and decreased gradually with increasing etching time. Further, the spherical craters with reduced curvature were uniformly distributed over the etched glass surface. The haze value increased sharply up to 55 % and the transmittance decreased by 90 % at 60 minutes of etching time. The ideal haze value range of 3~7 % and transmittance value range of above 90 % were achieved in the period of 240 to 720 minutes of etching time for the selected concentration of the chemical etchant.