• Title/Summary/Keyword: Nozzle distance

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Experimental Study on the Heat Transfer and Turbulent Flow Characteristics of Jet Impinging the Non-isothermal Heating Plate (비균일 온도분포를 갖는 평판에 대한 충돌제트의 열전달 및 난류유동특성에 관한 연구)

  • 한충호;이계복;이충구;이창우
    • Journal of Energy Engineering
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    • v.10 no.3
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    • pp.272-277
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    • 2001
  • An experimental study of jet impinging the non-isothermal heating surface with linear temperature gradient is conducted with the presentation of the turbulent flow characteristics and the heat transfer rate, represented by the Nusselt number. The jet Reynolds number ranges from 15,000 to 30,000, the temperature gradient of the plate is 2~4.2$^{\circ}C$/cm and the dimensionless nozzle to plate distance (H/D) is from 2 to 10. The results show that the peak of heat transfer rate occurs at the stagnation point, and the heat transfer rate decreases as the radial distance from the stagnation point increases. A remarkable feature of the heat transfer rate is the existence of the second peak. This is due to the turbulent development of the wall jet. Maximum heat transfer rate occurs when the axial distance from the nozzle to nozzle diameter (H/D) is 6 or 8. The heat transfer rate can be correlated as a power function of Prandtl number, Reynolds number, the dimensionless nozzle to plate distance (H/D) and temperature gradient (dT/dr). It has been found that the heat transfer rate increases with increasing turbulent intensity. The wall jet is influenced by temperature gradient and the effect becomes more important at higher radii.

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Augmentation of Heat Transfer on a Flat Plate with Impinging Water Jet (衝突水噴流 에 의한 熱傳達促進 에 관한 硏究)

  • 엄기찬;서정윤
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.6 no.4
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    • pp.301-307
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    • 1982
  • The purpose of this investigation is to study heat transfer characteristics at a stagnation point on a flat plate caused by upward impinging water jet. At the stagnation point, heat transfer results by impinging water jet are being compared with the ones with supplementary water. Optimum supplementary water quantity are supplied in order to improve the effect of heat transfer for each nozzle-to-plate distance. As the nozzle outlet velocity increases, the heat transfer coefficient at stagnation point consequently increases. Changing the nozzle-to-plate distance, growth rate of heat transfer also varies accordingly. This optimum range of Reynolds number is obtained to improve heat transfer effect.

The Experimental Study for Heat Transfer and Combustion Characteristics of Gaseous Impinging Jet Premixed Flame (예혼합 화염이 벽면에 충돌시 열전달 및 연소특성에 관한 실험적 연구)

  • 정은규;조경민;김호영
    • Transactions of the Korean Society of Automotive Engineers
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    • v.4 no.6
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    • pp.1-10
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    • 1996
  • In the present study, the structure and the characteristics of gaseous premixed flame impinging normal to the flat plate have been investigated experimentally. For the examination of the heat transfer and combustion characteristics, measurements of temperature, direct and schlieren photography were performed. The results of present study show that the length of inner flame becomes smaller as distance from nozzle exit to plate decrease. The width of flame becomes larger as air-fuel ratio decreases. The smaller Reynolds number at nozzle exit and the smaller distance from nozzle exit to plate lead to the higher heat transfer rate in the region of center of plate. As the air-fuel ratio decreases, the heat transfer at plate with moderate rate occurs on wide region.

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Effect of Injection Pressure on the Flash Boiling Spray from Simple Orifice Nozzle (인젝터 압력이 단공노즐 감압비등 분무에 미치는 영향)

  • Lee, Hyunchang;Cha, Hyunwoo;Kang, Donghyeon
    • Journal of ILASS-Korea
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    • v.27 no.1
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    • pp.42-49
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    • 2022
  • Flash boiling occurs in a couple of modern engineering systems and understanding its mechanism is important. In this experimental study, discharge coefficient of flash boiling spray from simple orifice nozzle was measured, and backlight imaging was acquired at injection pressure to 6.0 bar and temperature to 163℃ for the purpose. Pressurized water by pump was used for working fluid and was heated by electric heater and ejected through simple orifice nozzle diameter of 0.5 mm. High speed camera with long distance microscope was used for backlight imaging in two FoV having magnification of 3.3 and 0.64. The decrease of discharge coefficient according to degree of superheating and evolution of flash boiling spray imaged at various pressure and temperature were explained by the pressure field inside the injector.

Spray Characteristics of Electrostatic Pressure-Swirl Nozzle for Burner Application

  • Laryea, Gabriel Nii;No, Soo-Young
    • 한국연소학회:학술대회논문집
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    • 2002.06a
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    • pp.16-23
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    • 2002
  • Electrostatic pressure-swirl nozzle for practical oil burner application has been designed. The charge injection method has been used in this design, where the nozzle consists of a sharp pointed tungsten wire as a charge injector and the nozzle body grounded. The spray characteristics of the nozzles have been investigated by using an insulating liquid, i.e. kerosene without active surface agent. Breakup length of liquid decreased with an increase in applied voltage and injection pressure, while the spray angle increased with an increased in both applied voltage and injection pressure. An empirical equations have been suggested to predict the breakup length for electrostatic pressure-swirl atomizer. The experimental result was within the range of the predicted equations. The SMD decreased between the ranges of 2.8 ${\sim}$ 33% when the conventional nozzle was compared to the electrostatic with -10 kV applied to the electrode at a radial distance from 5 to 20 mm.

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Design Factors of Boom Sprayer(I) - Spray Patterns of Nozzles - (붐방제기 살포장치의 설계요인 구명을 위한 실험적 연구(I) -노즐의 분무유형-)

  • 정창주;김학진;조성인;최영수;최중섭
    • Journal of Biosystems Engineering
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    • v.20 no.3
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    • pp.217-225
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    • 1995
  • This study was conducted to find design factors of spraying device of the boom sprayer for low volume application. Four types of nozzles(standard flat nozzle, drift guard nozzle, even flat nozzle, and hollow cone nozzle) were used for the spray characteristic experiment. Spray patterns of the nozzles were distinguished by the nozzle type, spray distance, and spray direction. The flow rate was proportional to the square root of spray pressure in all nozzles. Increased nozzle height improved spray distribution at reduced pressures and/or increased spacing. Distribution tended to improve as pressure increased within the range of pressures used for fan nozzles.

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Flow Characteristics of Parallel Plane Jets (병렬평면제트의 유동특성)

  • Kim Dong-Keon;Yoon Soon-Hyun
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.823-826
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    • 2002
  • Experiments were conducted to show the characteristics of the flow on unventilated parallel plane jets. Measurements of mean velocity components and turbulent intensities were carried out with a particle image velocimetry. The measurements range of these experiments was Reynolds number of 5300 based on the nozzle width and the cases of nozzle-to-nozzle distance were 4, 6, 8, and 10 times the width of the nozzle. Results show that a recirculation zone with a sub-atmospheric static pressure was bounded by the inner shear layers of the individual jets and the nozzles plate. The positions, where maximum value of mean turbulent intensities and mean turbulent kinetic energy show, were at the same position with the merging point. The spread of jets in the merging region increases more rapidly than that of jets in the converging and the combined region. As nozzle-to-nozzle distances were increased, it was shown that merging and combined lengths were shorter.

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Temperature field measurement and CFD analysis of a jet impinging on a concave surface depending on changes in nozzle to surface distance and the diameter of a circular nozzle (원형 노즐의 직경 변화 및 표면으로 부터의 거리변화에 따른 오목한 표면에 충돌하는 제트의 온도장 측정 및 CFD해석)

  • Yeongmin Jo;Yujin Im;Eunseop Yeom
    • Journal of the Korean Society of Visualization
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    • v.21 no.2
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    • pp.55-62
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    • 2023
  • The characteristic of jet impinging on the concave surface were analyzed through thermographic phosphor thermometry (TPT) and numerical investigation. Under a jet Reynolds number of 6600, nozzle diameters and nozzle-to-surface distances (H/d) were changed 5mm and 10mm and H/d=2 and 5. The RNG k-ε turbulence model can accurately predict the distribution of Nusselt number, compared to other models (SST k-ω, realizable k-ε). Heat transfer characteristics varied with the nozzle diameter and H/d, with a secondary peak noted at H/d =2, due to vortex-induced flow detachment and reattachment. An increase in nozzle diameter enhanced jet momentum, turbulence strength, and heat transfer.

Study on Performance Evaluation of Mixing Section of Ejector using CFD simulation (CFD 시뮬레이션을 이용한 이젝터 혼합실 형상에 따른 성능 평가에 관한 연구)

  • Sin, Won-Hyeop;Kim, Min-Woo;Park, Young-Chul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.5
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    • pp.2610-2616
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    • 2014
  • An ejector is a kind of pump which is using pressure energy of high pressure fluid. This study aims to investigate performance influencing according to change the ejector mixing section shape using CFD simulation by Finite Volume Method. Optimum conditions were suggested 3 kind of variable such as nozzle diameter, nozzle length, distance from nozzle tip to the diffuser inlet. The results, It was confirmed that the diameter of the nozzle was the greatest effect in performance of the ejector. The diameter of the nozzle get smaller, mixing ratio was increased. On the other hand, nozzle length, distance from nozzle tip to the diffuser inlet had little effect on performance. It was proposed specific Mixing section, Nozzel diameter 23.8mm using the Artificial Neural Network.

An Experimental Study on Flow Characteristics of Impinging Jet (1) (충돌제트의 유동특성에 관한 실험적 연구(1))

  • 배석태;김동균;김시범
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.2
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    • pp.403-408
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    • 2001
  • The flow characteristics of impinging jet flow are affected greatly by nozzle plate to distance. An sharp edge nozzle was used to achieve uniform mean velocity at the nozzle inlet, and its diameter is 10 mm(d). Therefore, the flow characteristics on the impinging jet plate can be changed largely by the control of main flow. In the parent study, we investigate the effects of main flow length, its variable is nozle plate to distances(12d, 10d, 8d, 6d and 4d)

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