• Title/Summary/Keyword: Confined Jet Flow

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A Numerical Study on the Impinging Jet Flow Characteristics in the Presence of Applied Magnetic Fields (자기장이 인가된 충돌제트의 유동 특성에 관한 수치적 연구)

  • Lee Hyun Goo;Yoon Hyun Sik;Hong Seung Do;Ha Man Yeong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.5 s.236
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    • pp.537-544
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    • 2005
  • The present study numerically investigates two-dimensional fluid flow in the confined jet flow in the presence of applied magnetic field. Numerical simulations to calculate the fluid flow and heat transfer in the confined jet are performed for different Reynolds numbers in the absence and presence of magnetic fields in the range of $0{\le}N{\le}0.05$, where N is the Stuart number (interaction parameter) which is the ratio of electromagnetic force to inertia force. The present study reports the detailed information of flow in the channel at different Stuart numbers. As the intensity of applied magnetic fields increases, the vortex shedding formed in the channel becomes weaker and the oscillating amplitude of impinging jet decreases. The flow fields become the steady state if the Stuart number is greater than a critical value. Thus the pressure coefficients at the stagnation point also vary as a function of Stuart number.

A Numerical Study on the Heat Transfer Characteristics of Impinging Jet Flow in the Presence of Applied Magnetic Fields (자기장이 인가된 충돌제트의 열전달 특성에 관한 수치적 연구)

  • Lee Hyun Goo;Yoon Hyun Sik;Hong Seung Do;Ha Man Yeong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.6 s.237
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    • pp.653-661
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    • 2005
  • The present study numerically investigates two-dimensional fluid flow and heat transfer ir the confined jet flow in the presence of applied magnetic field. For the purpose of controlling vortex shedding and heat transfer, numerical simulations to calculate the fluid flow and heat transfer in the confined jet are performed for different Reynolds numbers in the absence and presence of magnetic fields and for different Prandtl numbers of 0.02 (liquid metal), 0.7 (air) and 7 (water) in the range of $0{\le}N{\le}0.05$, where N is the Stuart number (interaction parameter) which is the ratio of electromagnetic force to inertia force. The present study reports the detailed information of flow and thermal quantities in the channel at different Stuart numbers. As the intensity of applied magnetic fields increases, the vortex shedding formed in the channel becomes weaker and the oscillating amplitude of impinging jet decreases. The flow and thermal fields become the steady state if the Stuart number is greater than the critical value. Thus the Nusselt number at the stagnation point representing the heat transfer characteristics also vary as a function of Stuart number.

A Numerical Study of Flow and Heat Transfer on Two Dimensional Dual Impinging Jet on Nozzle to Plate Distance (이차원 이중 충돌제트에서 노즐과 충돌면 간격에 따른 유동 및 열전달에 관한 수치적 연구)

  • Kim, Sang-Kil;Kim, Dong-Keon;Kim, Moon-Kyung;Yoon, Soon-Hyun;Kim, Bong-Hwan
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.2804-2809
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    • 2008
  • Experimental results and numerical computations were conducted to investigate the effect of the confined wall on the flow and heat transfer characteristics for a two-dimensional impinging jet. Experimental results and Numerical solutions were obtained by using the particle image velocimetry and the commercial CFD code (CFX 11), respectively. The parameters studied were jet Reynolds number (Re=5,000), conditions of confined wall (unventilate), nozzle to plate spacings ($H/W=1{\sim}16$), and nozzle to nozzle spacing (S/W=6). Experimental and numerical results were agreed well with each other. The maximum heat transfer point was found variation of nozzle to plate spacings.

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Thermal and flow characteristics of confined multiple slot jet impingement with exhaust ports (배기구를 가진 국한된 다중 슬롯 충돌제트의 열유동 특성)

  • Kang, Soo-Jin;Cho, Woo-Jin;Lee, Jong-Hyeok;Lee, Kwan-Soo
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.835-840
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    • 2009
  • In this paper, confined multiple slot jet impingement with exhaust ports is investigated numerically. A flow cell, defined as volume sectioned by the impingement and confinement surfaces and the centerlines of adjacent nozzle and exhaust port, is chosen for computational domain. The effects of Reynolds number and geometrical parameters on the heat transfer performance and the flow characteristics are studied. For turbulence, the Abe-Kondoh-Nagano version of the low-Reynolds k-$\varepsilon$ model is employed. The results showed that the local Nusselt number distribution is shifted down and show poor heat transfer performance for small Reynolds number and small ratio of the lateral and axial length of flow cell. The rest of range, except the range of the shift phenomenon, can be classified into three groups by heat transfer characteristics.

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The Flow Field Structure of Jet-in-Cross Flow through the Perforated Damage Hole (관통 손상 구멍으로부터의 제트-교차 흐름의 유동장 구조)

  • Lee, Ki-Young
    • Journal of the Korea Institute of Military Science and Technology
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    • v.17 no.4
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    • pp.551-559
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    • 2014
  • The influence of the battle damage hole on the velocity and vorticity flow field have been studied by using particle image velocimetry. Time averaged velocity and vorticity vector fields in the vicinity of jet are presented. The perforated damage hole on a wing created from a hit by anti-air artillery was modeled as a 10% chord size hole which positioned at quarter chord. At low angles of attack, the vorticity in the forward side of the jet is cancelled due to mixing with the wing surface boundary layer. Stretching of vorticity in the backside of the jet generates a semi-cylindrical vortical layer that enclosing a domain with slow moving reverse flow. Conversely, at higher the angles of attack, the jet vorticity advected away from the wing surface and remains mostly confined to the jet. The mean flow behind the jet has a wake-like structure.

Effect of Surface Roughness on Two-Phase Flow Heat Transfer by Confined Liquid Impinging Jet (액체 충돌제트의 표면조도변화에 따른 이상유동 열전달 특성)

  • Yim, Seong-Hwan;Shin, Chang-Hwan;Cho, Hyung-Hee
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.8
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    • pp.714-721
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    • 2005
  • The water jet impingement cooling with boiling is one of the techniques to remove heat from high heat flux equipments. The configuration of surface roughness is one obvious condition of affecting the performance on heat transfer in nucleate boiling, The present study investigates the water jet impinging single-phase convection and nucleate boiling heat transfer for the effect of surface roughness to enhance the heat transfer in free surface and submerged jet. The distributions of the averaged wall temperature as well as the boiling curves are discussed. Jet velocities are varied from 0.65 to 1.7 m/s. Surface roughness by sand blast and sand paper varies from 0.3 to 2.51 ${\mu}m$ and cavity shapes on surface are semi-circle and v-shape, respectively The results showed that higher velocity of the jet caused the boiling incipience to be delayed more. The incipient boiling and heat transfer increase with increasing surface roughness due to a large number of cavities of uniform size.

Numerical Study of Laminar Flow in a Combustor with a Planar Fuel Jet (Planar-Jet형 연소내 층류유동의 전산해석)

  • Eom, Jun-Seok;Kim, Do-Hyeong;Yang, Gyeong-Su;Sin, Dong-Sin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.12
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    • pp.1644-1651
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    • 2000
  • In this study, the confined laminar flow and transport around a square cylinder with a planar fuel jet are numerically simulated. Both rear and front jets are considered, respectively. In each case, various ratios of the jet velocity to the fixed upstream velocity are taken into consideration. In case of the rear jet, the high mass-fraction region is formed along the streamlines from the jet exit, and the oscillation of the force on the square cylinder eventually disappears as the jet velocity is close to the upstream velocity. In case of the front jet, drag is significantly reduced when the jet velocity ratio is grater than 1. The results obtained exhibit flow and scalar-mixing charactered in a planar combustor.