• Title/Summary/Keyword: Hot wire anemometer

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Measurement of turbulent flow characteristics of a rectangular duct with a 180.deg. bend by hot wire anemometer (열선유속계에 의한 180.deg.곡관을 갖는 직사각 단면덕트에서의 난류유동 특성의 측정)

  • 박호영;유석재;최영돈
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.3
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    • pp.734-746
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    • 1990
  • Velocities and Reynolds stresses in 3-dimensional turbulent flow in rectangular ducts with a 180.deg. bend were measured by hot wire anemometer. Slant wire was rotated to 4 directions and I type wire was rotated to 2 directions and the voltage outputs of them were combined to obtain the mean velocities and Reynolds stresses. Flow characteristics in the 1.5:1 and 2:1 cross secioned 180.deg. bend were measured and the results were compared with the data from Moon for the square sectioned 180.deg. bend flow. Flows in rectangular sectioned 180.deg. bend show the reduction in secondary flow and therefore the reduction of double maximum in local mean velocities.

A Wind Tunnel Study on Influences of ILS Tower on Wind Speed Measurement (계기착륙장치 타워가 풍속관측에 미치는 영향에 관한 풍동실험연구)

  • Choi, Cheol-Min;Kim, Kye-Hwan;Kim, Young-Chul;Kwon, Kybeom
    • Atmosphere
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    • v.23 no.4
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    • pp.513-517
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    • 2013
  • In this study, it is first intended to simulate the vertical profile of atmospheric flow in a short wind tunnel. In order to accomplish it, proper devices are designed properly to reduce freestream flow momentum and it is confirmed from the measured velocity profile using hot-wire anemometer that momentum flux of the tunnel free stream can be reduced and desired atmospheric boundary can be created. Second, experiments are performed to identify influences of a surrounding structure measuring correct wind velocity by an anemometer, which are located nearby due to area limitation in actual airport and correction factors are proposed from experimental results. One of findings is that in order to limit the velocity attenuation due to a nearby structure under 10%, wind velocity measuring equipment should be installed at least 6 times of the structure height away from the structure of concern.

Measurements of Turbulent Flows in the $180^{\circ}$ Curved Duct by Hot-wire Anemometer (열선유속계를 이용한 $180^{\circ}$ 곡덕트 내 난류유동의 측정)

  • Han, Seong-Ho;Kim, Won-Kap;Choi, Young-Don
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.729-734
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    • 2003
  • This paper reports the characteristics of the three dimensional turbulent flow in the rectangular-sectioned 180 degree bends by Hot-wire anemometer. Grande and Kool proposed a cooling law for the measurements of the flow through the narrow passage. The authors noticed that the calibration coefficients of original method are not constant and fairly sensitive to the flow approaching angle. Measured voltages are converted to three velocity and six Reynolds stress components using the modified method in which the coefficients are treated as a function of approaching angle.

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Measurement of Outward Turbulent Flows Subject to Plane Rate of Strain in a Rotating 90 Deg. Curved Duct of Variable Cross-Section (단순변형률 조건 하의 회전하는 가변단면 $90^{\circ}$ 곡덕트내 외향 난류유동 측정)

  • Oh, Chang-Min;Choi, Young-Don
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.5
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    • pp.623-631
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    • 2000
  • Hot-wire measurements were carried out on the developing turbulent flows subject to plane rate of strain in a rotating curved duct. The cross-section of the curved duct varies from 100mm${\times}$50mm rectangular shape at the bend inlet gradually to the 50mm${\times}$100mm rectangular shape at the bend outlet. Experimental setup consists of the test section of $90^{\circ}$ curved duct, rotating disc of 1.95m diameter, Ag-Ni precision slip ring, automatic traversing mechanism, variable speed motor, centrifugal blower, orifice flowmeter and hot-wire anemometer. Data signals from the rotating curved duct are transmitted through the slip ring to the computer which is located at the outside of the rotating disc. 3-dimensional velocity and 6 Reynold stresses components were obtained from the fluctuating and mean voltage measured by the slant type hot-wire probe rotating into 6 orientations. We investigate the effects of Coriolis and centrifugal forces on the turbulence structure.

Investigation on the Turbulent Flow Field Characteristics of a Gun-Type Gas Burner with and without a Duct (덕트의 유무에 따른 Gun식 가스버너의 난류유동장 특성 고찰)

  • Kim, J.K.;Jeong, K.J.
    • Journal of Power System Engineering
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    • v.10 no.4
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    • pp.17-24
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    • 2006
  • The turbulent flow field characteristics of a gun-type gas burner with and without a duct were investigated under the isothermal condition of non-combustion. Vectors and mean velocities were measured by hot-wire anemometer system with an X-type hot-wire probe in this paper. The turbulent flow field with a duct seems to cause a counter-clockwise recirculation flow from downstream to upstream due to the unbalance of static pressure between a main jet flow and a duct wall. Moreover, the recirculation flow seems to expand the main jet flow to the radial and to shorten it to the axial. Therefore, the turbulent flow field with a duct increases a radial momentum but decreases a axial momentum. As a result, an axial mean velocity component with a duct above the downstream range of about X/R=1.5 forms a smaller magnitude than that without a duct in the inner part of a burner, but it shows the opposite trend in the outer part.

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Manufacure of Hot-Wire Anemometer and the Improvement of Its Performance (열선유속계의 시작 및 성능 향상에 관한 연구)

  • 이택식;고상근
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.10 no.4
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    • pp.541-557
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    • 1986
  • 본 연구에서는 캐패시턴스 성분을 고려한 브리지(bridge) 모델을 적용하여 지 금까지 설명할 수 없었던 문제를 설명함으로서 이 모델의 정당성을 확인하고자 하며, 더욱 나아가 다른 여러가지 변수에 대한 응답특성의 예측을 가능하게 하고자 한다.

Investigation on the Turbulent Swirling Flow Field within the Combustion Chamber of a Gun-Type Gas Burner (Gun식 가스버너의 연소실내 난류 선회유동장 고찰)

  • Kim, Jang-Kweon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.9
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    • pp.666-673
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    • 2009
  • The turbulent swirling flow field characteristics of a gun-type gas burner with a combustion chamber were investigated under the cold flow condition. The velocities and turbulent quantities were measured by hot-wire anemometer system with an X-type probe. The turbulent swirling flow field in the edge of a jet seems to cause a recirculation flow from downstream to upstream due to the unbalance of static pressure between a main jet flow and a chamber wall. Moreover, because the recirculation flow seems to expand the main jet flow to the radial and to shorten it to the axial, the turbulent swirling flow field with a chamber increases a radial momentum but decreases an axial as compared with the case without a chamber from the range of about X/R=1.5. As a result, these phenomena can be seen through all mean velocities, turbulent kinetic energy and turbulent shear stresses. All physical quantities obtained around the slits, however, show the similar magnitude and profiles as the case without a chamber within the range of about X/R=1.0.

Velocity Measurement Technique in a Narrow Passage by Hot-wire Anemometer (열선유속계를 이용한 좁은 유로 내 유속 측정법)

  • Kim, Won-Kap;Han, Seong-Ho;Choi, Young-Don
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.19 no.2
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    • pp.191-201
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    • 2007
  • It was noted by the several researchers that the voltage outputs in response to a single yawed hot-wire sensor in a flow perpendicular to the axis deviate from the theoretical voltage output by King's law and Jorgensen's relation. This study noticed that the calibration coefficients of original Grande's method are not constant and fairly sensitive to the radial angle (${\alpha}_{R}$). For more accuracy, this study interpolated the parameters of the Grande relation as a function of radial angle and compared velocity components with ones by Jorgensen and original Grande relation in the calibration jet flow. Finally, as a test case, 3-dimensional turbulent flows of the inlet plane of 180 degree bend are measured and compared the velocity components by above three methods and showed the characteristics of the flows.

The Effects of the Intake Value Type on the Intake Flow(I) -The Axial Velocity Distribution by the Model- (흡입밸브 형상이 흡입유동에 미치는 영향(I) -모델에 의한 축방향속도분포-)

  • 하대진;박경석
    • Journal of the korean Society of Automotive Engineers
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    • v.11 no.6
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    • pp.57-67
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    • 1989
  • This paper deals with the experimental study of the turbulent flow fields by the hot-wire anemometer and the density fields by the Schlieren photography. In this study, the air mixed with CO$_{2}$ was used to visualize and to study this process and experimental parameters used were valve lift and valve shape. The results obtained are as follows: 1) The axial velocity of mixture flow passing a valve is changed greatly by valve seat angle and valve lift. Especially, it is changed more when the valve seat angles is 30.deg. and 45.deg. than when these are 60.deg. and 90.deg. 2) Experimental results by hot wire anemometer and Schlieren apparatus are very close together. The most satisfactory results are shown when the valve seat angle is 45.deg.

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An Experimental Study on the Characteristics of Air Flow Velocity Distritutions Inside a Rolling Tire -Unloaded Rolling Tire- (회전하는 타이어 내부공기의 유동특성에 관한 실험적 연구 -무부하 회전구동 타이어-)

  • 김윤제;조정현
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.6
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    • pp.174-181
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    • 1999
  • in order to elucidate the characteristic of velocity distribution of the cavity air. Exploratory tests were conducted on an unloaded rolling radial tire operated at various speeds and inflation pressure. A hot-wire anemometer, rotating with the tire, was used to measure the flow velocity inside the tire cavity. Tow different types of experiments were performed ; one for the effects of rolling speed with constant inflation pressure, the other for the various cavity pressures with constant rolling speed. Experimental results are given as plots of the mean velocity distributions versus the distance from the rim. It is observed that the magnitude of mean velocity in the cavity air shows increasing natures with the increasing of the inflation pressures and rolling speeds.

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