• Title/Summary/Keyword: Uniformity of velocity

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A Study on the Characteristics of Air flow Fields with Velocity Uniformity in a Wind Tunnel (풍동장치 내 공기 유동장과 속도 균일도 특성에 대한 분석)

  • Han, Seok Jong;Lee, Sang Ho;Lee, Jae Gyu
    • Journal of the Korean Society of Visualization
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    • v.16 no.3
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    • pp.59-64
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    • 2018
  • Numerical simulations were carried out to analyze the flow characteristics of the wind tunnel. Flow field characteristics with velocity uniformity at the test sections are largely affected by inlet conditions of air flow rate and temperature. Axial average velocity of the flow field inside the test area was almost linearly decreased by 0.026% each 1m. The uniformity distributions of axial velocity showed the highest reduction rate of about 24% between nozzle outlets 1 ~ 2m. In addition, average velocity and the uniformity are increased with air temperature in the wind tunnel due to density variation. The results of this paper are expected to be useful for the basic design of wind tunnel and to be used for efficient design.

Flow Uniformity Analysis of DOC-DPF System using CFD (CFD를 활용한 DOC-DPF 조합의 유동 균질도 분석)

  • Kim, Taehoon;Park, Sungwook
    • Journal of ILASS-Korea
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    • v.24 no.3
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    • pp.122-129
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    • 2019
  • Flow uniformity in aftertreatment system is an important factor in determining uniform catalytic reaction and filtration. In this study, variety types of DOC-DPF system design were analyzed to increase flow uniformity. For this analysis, ANSYS Fluent was used with porous media setup for DOC and DPF. Turbulent flow was modeled by standard $k-{\varepsilon}$ model excepting porous media. Uniformity index was utilized to evaluate the flow uniformity quantitatively. Reference design showed low velocity region because two large vortex were generated before baffle. When radius of DOC-DPF system was increased, exhaust pressure acting on the inlet decreases and velocity distribution was shifted to one side. When inlet pipe was set to axial center of DOC-DPF system velocity distribution was symmetric. However, flow was not dissipated until the front end of DOC and showed higher uniformity index. When the volume of DOC was reduced while fixed volume of entire DOC-DPF system and baffle plate is located downstream of the DOC-DPF system, there was improvement in uniformity index.

NUMERICAL OPTIMIZATION OF TEMPERATURE DISTRIBUTION IN HRSG SYSTEM USING INLET GUIDE VANE (전치 가이드 베인 설치에 따른 열회수 보일러 입구 온도 최적화)

  • Lee, Soo-Yoon;Ahn, Joon;Shin, Seung-Won
    • Journal of computational fluids engineering
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    • v.14 no.3
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    • pp.1-8
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    • 2009
  • Diverging channel from gas engine exit to the inlet section of Heat Recovery Steam Generator (HRSG) has been re-designed for 1 MW system. To improve the uniformity in velocity and temperature distribution of existing design(Case A and B), two additional test geometries have been chosen for the numerical simulation. At first, gas burner exit section has been centered to the inlet section of the boiler(Case C) and uniformity in velocity and temperature distribution has been improved considerably. Secondly, the diverging channel length can be further reduced to compact geometry with new guide vane design (Case D and E). Proposed design shows overall improvement in uniformity in velocity and temperature distribution compared to existing one.

CFD Based Shape Design of Guide Vane for Fan Filter Unit (전산유체해석을 이용한 Fan Filter Unit(FFU)의 가이드 베인 형상설계)

  • Jang, Jun Hwan;Ahn, Joon;Myong, Hyon Kook
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.37 no.7
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    • pp.709-716
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    • 2013
  • A fan filter unit (FFU) is a device which supplies clean air from the ceiling in a clean room. With an increase in its size, velocity variation occurs within the exhaust plane and this damage the product quality or productivity. Hence, a guide vane is installed inside the device to enhance the velocity uniformity. Because the vane reduces the flow rate for a given pumping power, an optimum design is required to achieve velocity uniformity while minimizing the flow rate reduction at the same time. To find a geometry that satisfies these requirements, a series of numerical simulations has been conducted while changing the angle and length of the guide vanes. By changing the geometry of the side guide vane, the velocity uniformity increased by 3.7% and the flow rate decreased by 1.5%. For the center guide vane, the velocity uniformity increased by 2.9% and the flow rate decreased by 0.7%.

Calibration of Water Velocity Profile in Circular Water Channel Using Particle Image Velocimetry (PIV를 이용한 회류수조의 유속 분포 교정에 관한 연구)

  • Suh, Sung-Bu;Jung, Kwang-Hyo
    • Journal of Ocean Engineering and Technology
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    • v.25 no.4
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    • pp.23-27
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    • 2011
  • This experimental study was performed to find rpms of the impeller and the surface flow accelerator to make a uniform velocity vertical distribution in the circular water channel. PIV technique was employed to measure the water velocity profiles into the water depth from the free surface. The number of instantaneous velocity profiles was decomposed into mean and turbulence velocity components, and the distribution of velocity fluctuation and turbulence intensity were computed for each experimental condition. From these results, the velocity uniformity was quantitatively determined to present the flow quality in the measuring section of the circular water channel. It has been shown that the proper operation of the surface flow accelerator would make the uniform velocity profiles and reduce the velocity fluctuation near the free surface.

Relationship between ICAC EP-7 and %RMS, Standards for Gas Flow Uniformity inside Electrostatic Precipitators (전기집진기 내부 유동 균일도 평가 기준인 ICAC EP-7과 %RMS 간 상관관계)

  • Shin, Wan-Ho;Hong, Won-Seok;Song, Dong-Keun
    • Journal of Korean Society for Atmospheric Environment
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    • v.26 no.2
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    • pp.234-240
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    • 2010
  • Gas flow uniformity is an important factor to guarantee particle removal performance of electrostatic precipitators (EP), and the gas flow uniformity is evaluated by a fraction of standard deviation to the mean of gas flow distribution (%RMS) or a technical standard, ICAC EP-7, provided by The Institute of Clean Air Companies. In this study, relationship between the ICAC EP-7 and %RMS in evaluation of gas flow uniformity was investigated in terms of flow velocity. The maximum values of %RMS for gas velocity distribution of normal distribution has been obtained, and the maximum values of %RMS with gas velocity distribution satisfying ICAC EP-7 standards were also evaluated. With gas flow distribution obtained from CFD analysis and physical model test of real EP, %RMS values were calculated and it was tested if those gas flow distribution satisfy the criteria specified in ICAC EP-7. The %RMS values satisfying criteria of ICAC have been appeared to have similar values with %RMS values calculated with normal distribution of gas velocities.

A Numerical Study on the Flow Uniformity according to Chamber Shapes Used for Test of the Semi-Conductor Chip (반도체 칩 테스트용 챔버 형상에 따른 유동 균일성에 대한 수치적 연구)

  • LEE, DAEGYU;MA, SANG-BUM;KIM, SUNG;KIM, JEONG-YEOL;KANG, CHAEDONG;KIM, JIN-HYUK
    • Transactions of the Korean hydrogen and new energy society
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    • v.31 no.5
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    • pp.480-488
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    • 2020
  • This study was conducted to improve the flow uniformity inside the chip tester through changing the flow path formation according to the inlet and outlet position of chamber. The internal flow and velocity distributions of the modified chamber models (Cases 1-3) were compared with the reference chamber model through three-dimensional Reynolds-averaged Navier-Stokes equations with k-ε turbulence model. The modified chamber models showed the superior flow uniformity characteristics compared to the reference chamber model. To investigate the flow uniformity in the chip tester, the standard deviation of the velocity was defined and compared. Through the internal flow analysis and assesment of the standard deviation, Case 2 among the test cases including the reference model showed the best flow uniformity generally.

Velocity and Friction Force Distribution in Rotary CMP Equipment (회전형 CMP장비의 속도 및 마찰력 분포 해석)

  • Kim, Hyeong Jae;Jeong, Hae Do;Lee, Eung Suk;Sin, Yeong Jae
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.5
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    • pp.39-39
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    • 2003
  • As the design rules in semiconductor manufacturing process become more and more stringent, the higher degree of planarization of device surface is required for a following lithography process. Also, it is great challenge for chemical mechanical polishing to achieve global planarization of 12” wafer or beyond. To meet such requirements, it is essential to understand the CMP equipment and process itself. In this paper, authors suggest the velocity distribution on the wafer, direction of friction force and the uniformity of velocity distribution of conventional rotary CMP equipment in an analytical method for an intuitive understanding of variation of kinematic variables. To this end, a novel dimensionless variable defined as “kinematic number” is derived. Also, it is shown that the kinematic number could consistently express the velocity distribution and other kinematic characteristics of rotary CMP equipment.

Velocity and Friction Force Distribution in Rotary CMP Equipment (회전형 CMP장비의 속도 및 마찰력 분포 해석)

  • 김형재;정해도;이응숙;신영재
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.5
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    • pp.29-38
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    • 2003
  • As the design rules in semiconductor manufacturing process become more and more stringent, the higher degree of planarization of device surface is required for a following lithography process. Also, it is great challenge for chemical mechanical polishing to achieve global planarization of 12” wafer or beyond. To meet such requirements, it is essential to understand the CMP equipment and process itself. In this paper, authors suggest the velocity distribution on the wafer, direction of friction force and the uniformity of velocity distribution of conventional rotary CMP equipment in an analytical method for an intuitive understanding of variation of kinematic variables. To this end, a novel dimensionless variable defined as “kinematic number” is derived. Also, it is shown that the kinematic number could consistently express the velocity distribution and other kinematic characteristics of rotary CMP equipment.

NUMERICAL OPTIMIZATION OF TEMPERATURE DISTRIBUTION IN HRSG SYSTEM USING INLET GUIDE VANE (전치 가이드 베인 설치에 따른 열회수 보일러 입구 온도 최적화)

  • Lee, Soo-Yoon;Ahn, Joon;Shin, Seung-Won
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03a
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    • pp.148-154
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    • 2008
  • Diverging channel from gas burner exit to the inlet section of Heat Recovery Steam Generator (HRSG) has been re-designed for 1 MW system. To improve the uniformity in velocity and temperature distribution of existing design(Case A and B) of 300 kW HRSG system, two additional test geometries have been chosen for the numerical simulation. At first, gas burner exit section has been centered to the inlet section of boiler(Case C) and uniformity has been improved considerably. Secondly, the diverging channel length can be further reduced for compact geometry with new guide vane design (Case D and E). Proposed design shows overall improvement in uniformity in velocity and temperature distribution compared to existing one.

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