• 제목/요약/키워드: J-Nozzle

검색결과 362건 처리시간 0.024초

노즐특성에 따른 MIST-COOLING 열전달에 관한 실험적 연구 (The Effect of Nozzle Characteristics on the Mist-Cooling Heat Transfer)

  • 이진원;강영규;백병준;박복춘
    • 열처리공학회지
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    • 제5권3호
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    • pp.171-178
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    • 1992
  • The effect of nozzle characterristics on the mist-cooling heat transfer was investigated under the various flow conditions. Two different types of twin fluid nozzle were used, one is a $90^{\circ}$ angle tip nozzle with needle and the other is a $90^{\circ}$ angle tip non-needle nozzle. The cooling rate from the heated surface was measured and obtained the boiling curve as a function of surface temperature. An immersion sampling was employed for the measurement of droplet size of the spray. As a result of this experiment, the liquid sheet type nozzle shows better atomization when the mass ratio Mr>2.0, and collects more liquid droplets on the heated surface that results in better cooling effect. It was found that the maximum heat flux and heat transfer coefficient increased with increase in the volumetric flow rate, whereas the maximum heat flux decreased with increase in spray distance. The cooling effect depends upon the amount of collected droplet and droplet size, but it strongly depends upon the amount of collected droplet.

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Atomize 법에 의한 용융소재의 고효율 미세화에 관한 연구 (제1보:공기제트에 의한 액체의 공급기구) (A STUDY ON HIGH-EFFICIENCY ATOMIZATION OF MOLTEN MATERIALS (PART 1: AN EXPERIMENTAL STUDY ON SUPPLYING MECHANISM BY AIR JETS))

  • 오재건;이충원;석지권
    • 한국분무공학회지
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    • 제2권2호
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    • pp.35-42
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    • 1997
  • An innovating technique of atomizer has been proposed to supply and to atomise molten materials. Both of a simple geometry of nozzle and an improved nozzle have been fabricated in the present study. With these nozzles, characteristics of the suction and disintegration have been empirically investigated. The important conclusions are as follows; In the case of a simple nozzle: 1) Although the sucking up and supplying of molten materials are available, the applications of powder metallurgy are limited. 2) It is concluded that the more air flow rate, $W_A$ or the shorter the height of air nozzle from the surface of supplied water, $L_h$, the more the atomizing mass of liquids, $W_L$. In the case of an improved nozzle: 3) The stable liquids can be supplied due to cut off the passage of surrounding air entrainment by air jets. 4) The atomizing mass of liquids, $W_L$ has affected not so much on the height of nozzle from the surface of supplied water, $L_h$ as that from the orifice, hc.

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Atomize법에 의한 용융소재의 고효율 미세화에 관한 연구(제2보 : 이젝터의 원리를 이용한 액체노즐의 액체공급 및 액막생성 기구와 특성) (A Study on the High-Efficiency Atomisation Molten Materials (PART 2 : A Study on the Mechanism of Liquid Supplying and Film Formation by Applying the Ejector Principle))

  • 오재건;조일영
    • 한국분무공학회지
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    • 제3권2호
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    • pp.14-23
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    • 1998
  • The negative pressure as much as 10's mmHg is demanded at nozzle inside, in case of atomizing the large density molten materials. by conventional air jet nozzle. In this study, suction type fluid nozzle is designed by applying the ejector principle in order to clarify the air flow of nozzle inside, mechanism of liquid suction and liquid film formation. The results of this experimental study areas follows. Suction force of liquid is magnified by using liquid nozzle, and it is able to supply the liquid stable. Negative pressure at nozzle inside is varied by throttle angle of liquid nozzle, position and outer diameter of air jet nozzle, and have a influence on liquid suction quantity and liquid film formation.

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Side Jet 발생기의 유동특성에 관한 해석 (Numerical Analysis on the Flow Characteristics of Side Jet Thruster)

  • 홍승규;성웅제
    • 한국전산유체공학회지
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    • 제6권3호
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    • pp.27-31
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    • 2001
  • For rapid and abrupt control of a missile in supersonic flight, side jet on a missile body is found to be a useful device as evidenced by recent missile development at several nations. The magnitude of the side jet and the duration of it decide the level of control of such a missile system. In this paper, the aerodynamic characteristics of the side jet device itself are examined in terms of key parameters such as the side jet nozzle geometry, the chamber pressure and temperature. Specifically attention is paid to the effect of the chamber shape between the straight nozzle and the bent nozzle by 90 degrees on the nozzle flow properties. The thrust magnitudes are compared between the two shapes. Whether the way the nozzle is bent at the joint affects the nozzle performance is also investigated. Effects of the length and the divergence angle of the nozzle on the thrust are also quantified among three different side jet nozzles.

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Air-twist 노즐 형상 설계의수치적 연구 (A COMPUTATIONAL APPROACH TO DESIGN THE GEOMETRY OF THE AIR-TWIST NOZZLE)

  • 쥬래바 막슈다;송동주
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2010년 춘계학술대회논문집
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    • pp.67-70
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    • 2010
  • Spandex yarn requires a twisting process during winding and unwinding processes at the textile industry. The air-twist nozzle is widely used as part of the winding and unwinding. This paper describes computational approach to design the geometry of the air-twist nozzle. The nozzle has circular yarn-channel and the air-inlet which is perpendicularly connected to the yarn-channel with yarn-loading slit. The air-inlet of the nozzle is designed while measurements of the yarn-channel are fixed. The airflow inside the air-twist nozzle is simulated by using Computational Fluid Dynamic model. The Ansys CFX was used to perform steady simulations of the airflow for the air-twisting process. The vortical structure and the airflow pattern such as velocity streamline, vorticity, velocity of the air-twist nozzle are discussed. Computational results are compared with experimental results in this paper.

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이중판 노즐형 지지격자 스프링의 지지 강성감소를 위한 형상 개선 (Shape Modification for Decreasing the Spring Stiffness of Double-plated Nozzle Type Spacer Grid Spring)

  • 강흥석;송기남;이재호;이강희
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 추계학술대회논문집A
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    • pp.400-405
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    • 2001
  • Nozzle of the double-plated grid plays the role of the spring to support a fuel rod as well as to provide the coolant path in grid. The nozzle was known to be necessary to reduce the spring stiffness for supporting performance. In this study the contact analysis between the fuel rod and the nozzle type spacer grid was performed by using ABAQUS standard to propose the preferable shape in tenn of spring performance. Two small cuts at the upper and lower part of the nozzle appeared to have a minor effect in decreasing the nozzle stiffness. A long slot at the center of the nozzle was turned out not only to decrease the spring constant as desired but also to increase the elastic displacement.

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스월분무특성에 미치는 점성의 영향 (The Effect of Viscosity on the Spray Characteristics of Pressure Swirl Atomizer)

  • 윤석주;조대진
    • 한국분무공학회지
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    • 제4권4호
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    • pp.24-29
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    • 1999
  • In the pressure swirl atomizer, the liquid is injected through tangential passages into a swirl chamber, from which it emerges with both tangential and axial velocity components to form a thin conical sheet at the nozzle exit. This sheet rapidly attenuates, finally disintegrating into ligaments and then drops. The purpose of this study is to measure the spray characteristics according to variation of viscosity of the spray produced by the pressure swirl atomizer. The nozzle tested here were especially designed for this investigation. The discharge coefficient is determined by measuring the volume flow rate with a flow meter and the cone angle of the liquid sheets issuing from the nozzle is obtained from series of photographs of the sheet for various liquid viscosity and injection pressure. And mean drop size is measured by image processing method. It is found that the geometrical characteristics of the nozzle and the variation of viscosity were the influential parameters to determine the spray characteristics such as the cone angle, discharge coefficients and SMD.

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정전기력 방식의 Drop-on-Demand 토출을 위한 MEMS 잉크젯헤드 제작 (Fabrication of MEMS Inkjet Head for Drop-on-Demand Ejection of Electrostatic Force Method)

  • 손상욱;김영민;최재용;고한서;김용재;변도영;이석한
    • 전기학회논문지
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    • 제56권8호
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    • pp.1441-1444
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    • 2007
  • This paper presents a novel electrostatic drop-an-demand ejector with a conductive pole inside nozzle. The MEMS fabricated pole-type nozzle shows a significant improvement in the performance and reliability of forming meniscus and generating a micro dripping mode of droplet out of the meniscus. It is verified experimentally that the use of the pole-type nozzle. The liquid is used D20+SDS+SWNT (5 %wt). The gap between upper electrode and nozzle is about 600 um. Electrostatic drop-an-demand ejection is observed when a DC voltage of 1.5 kV is applied between the control electrode and ground electrode. Droplet diameter is $100{\mu}m$.

스월 강도에 의한 상압 플라즈마 토치의 최적 설계 (Optimal Design of Atmospheric Plasma Torch with Various Swirl Strengths)

  • 문장혁;김윤제;한전건
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 춘계학술대회
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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.

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분무특성에 따른 중유연소 수치해석의 결과와 실험과의 비교 (Comparison between heavy oil combustion test and numerical analysis of combustion phenomena subject to changes in injection characteristics)

  • 이승수;김혁주;김종진;최규성
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 추계학술대회
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    • pp.338-343
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    • 2003
  • Computations were performed to investigate the spray characteristics of the twin fluid nozzle in three stage heavy-oil combustion burner. The burner geometry and flow conditions were provided by a burner company. The goal of the study is to estimate mean droplet size, initial velocity and spread factor of the nozzle through comparison between experiments and numerical analyses. Air stage ratio is 2:4:4 by mass, and O2 in exhaust gas is about 4 % by volume. Here, the agreement between the experiment and numerical analyses is evaluated by NOx generation. Spray characteristics will be linearly interpolated between fuel consumption rate l20L/h and 240 L/h.

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