• Title/Summary/Keyword: Axial flow fan

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Analysis of Flow Characteristics on the Axial Flow Fan with Centrifugal Blade (원심형 날개를 부착한 축류홴의 유동특성 해석)

  • Choi Jung-Geun;Lee Seok-Jong;Lee Myoeng-Ho;Sung Jae-Yong
    • Journal of Advanced Marine Engineering and Technology
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    • v.30 no.5
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    • pp.589-596
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    • 2006
  • This study aims to propose a new model axial flow fan which attachs centrifugal blades, and to investigate the effect of centrifugal blades on the performance improvement of new model axial flow fan. A numerical simulation has been conducted using STAR-CD commercial code to solve the three dimensional incompressible Navier-Stokes equation for high Reynolds number $k-{\epsilon}$ turbulent model. Numerical simulation is carried out to investigate the detail phenomenon in the flow field and performance characteristics of new model and normal model fan. Calculation results are compared with normal model's results to investigate which centrifugal blades effect on velocity profile and pressure distribution at various flow field positions. and calculation results show that new model fan can improve the performance of total pressure.

Experimental Study on the Unsteady Flow under Various Operating Conditions of a Counter Rotating Axial Flow Fan (엇회전식 축류팬의 작동조건 변화에 따른 비정상 유동에 관한 실험적 연구)

  • Kang, Hyun-Koo;Cho, Lee-Sang;Cho, Jin-Soo
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1389-1394
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    • 2004
  • Experiments were done for the unsteady flow in a counter rotating axial flow fan near peak efficiency and stall point. Flow fields in a counter rotating axial flow fan were measured at cross-sectional planes of the upstream and downstream of each rotor. Cross sectional passage flow patterns were investigated through the acquired data by the $45^{\circ}$ inclined hot-wire. Comparison of flow characteristics between two different operating conditions such as tip vortex, secondary flow and turbulence intensity were performed through the analyses of axial, radial and tangential velocity distributions. As a result, tip vortex and secondary flows are enforced and measured obviously at stall point.

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Experimental Study on the Three Dimensional Unsteady Flow in a Counter Rotating Axial Flow Fan (엇회전식 축류팬의 3 차원 비정상 유동에 관한 실험적 연구)

  • Park, Hyun-Soo;Cho, Lee-Sang;Kang, Hyun-Koo;Cho, Jin-Soo
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.822-827
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    • 2003
  • Experiments were done for the three dimensional unsteady flow in a counter rotating axial flow fan under stable operating condition. Flow fields in a counter rotating axial flow fan were measured at cross-sectional planes of the upstream and downstream of each rotor. Cross sectional flow patterns were investigated through the acquired data by the $45^{\circ}$ inclined hot-wire. Flow characteristics such as tip vortex, secondary flow and tip leakage flow were confirmed through axial, radial and tangential velocity vector plot. Swirl velocity, which was generated by the front rotor, was recovered in the form of static pressure rise by the rear rotor except for hub and tip regions.

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A Numerical Investigation of Flow and Performance Characteristics of a Small Propeller Fan Using Viscous Flow Calculations

  • Oh, Keon-Je;Kang, Shin-Hyoung
    • Journal of Mechanical Science and Technology
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    • v.16 no.3
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    • pp.386-394
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    • 2002
  • The present work is aimed at investigating an unusual variation in flow and performance characteristics of a small propeller fan at low flow rates. A performance test of the fan showed dual performance characteristics, i.e., radial type characteristics at low flow rates and axial type at high flow rates. Dual performance characteristics of the fan are numerically investigated using viscous flow calculations. The Finite Volume Method is used to solve the continuity and Navier-Stokes equations in the flow domain around a fan. The performance parameters and the circumferentially averaged velocity components obtained from the calculations are compared with the experimental results. Numerical values of the performance parameters show good agreement with the measured values. The calculation simulates the steep variations of performance parameters at low flow rates and shows the difference in the flow structure between high and low flow rates. At a low flow coefficient of $\Phi$=0.2, the flow enters the fan in an axial direction and is discharged radially outward at its tip, which is much like the flow characteristics of a centrifugal fan. The centrifugal effect at low flow rates makes a significant difference in performance characteristics of the fan. As the inlet flow rate increases, flow around the fan changes into the mixed type at $\Phi$=0.24 and the axial discharge at $\Phi$=0.4.

A Study on the Flow Characteristics Around an Axial Fan of Rotary Burner (로터리 버너의 축류형 팬 주위 유동특성 연구)

  • Ko, D.G.;Cho, D.J.;Yoon, S.J.
    • Journal of ILASS-Korea
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    • v.8 no.1
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    • pp.1-8
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    • 2003
  • The flow analysis of the axial fan of rotary burner was performed by SIMPLE(Semi Implicit Method for Pressure Linked Equations) algorithm and finite volume mothod performed in the case of 3-D, incompressible, turbulent flow. In this study, the coordinate transformation was adapted for the complex geometry of axial fan, and the standard $k-{\varepsilon}$ model and wall function method were used for analysis of turbulent flow. Multi-block grid system was used for flow field and divided into four domains such as the inlet, outlet, flow field of rotating vane, and tip clearance. Fan rotation was simulated by rotational motion using MRF(Multiple Rotating Reference Frame) in steady, incompressible state flow.

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Study on Noise Reduction of An Axial Flow Fan According to the System Characteristics (시스템 특성을 고려한 축류팬 저소음화에 대한 연구)

  • Yoon, Hong-Yeol;Kim, Chang-Jun;Song, Sung-Bae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1381-1385
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    • 2000
  • In this paper, a guideline of axial flow fan design for noise reduction of refrigerators is p resented. Refrigerators have components which have a role to screen particular frequency air borne-noise which is generated by an axial flow fan set in them. Effective ways to use the particular characteristic of refrigerators are shown in this study. As a result of application of the methods, we reduced the noise of the target systems by more than 3 dB(A) from the viewpoint of air-borne noise produced by the axial flow fan set.

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Study on Noise Reduction of an Axial Fan for Refrigerator through Modification of the Blade Tip (깃 끝단 개선을 통한 냉장고용 축류홴 저소음화에 대한 연구)

  • 김창준;전완호;정용규
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.639-644
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    • 2002
  • In this paper, a successful noise reduction of an axial flow fan for a refrigerator is presented. The vortex sheet generated at the blade tip of fan was suppressed by changing the shape of the tip. The structure of vortex sheet and detailed flow pattern around the fan were studied by two-dimensional LDV(Laser-Doppler Velocimetry). Effective ways to work out the result as mentioned above are to make the tip of the blade varied in thickness and to have elliptical shapes. To seek the optimal value fur the shape of new fan, several cases were examined. Through the application of the methods, the refrigerator became less noisy by 3.8 dB(A) in terms of air-borne noise produced only by the axial flow fan compared to the current one.

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A Study on the Three Dimensional Statistical Turbulent Flow Characteristics Around a Small-Sized Axial Fan for Refrigerator (냉장고용 소형 축류홴의 통계학적 3차원 난류유동 특성에 관한 연구)

  • Kim, Jang-Gwon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.6
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    • pp.819-828
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    • 2001
  • The operating point of a small-sized axial fan is strongly dependent upon the system resistance. Therefore, the turbulent flow characteristics around a small-sized axial fan may change significantly according to the operating point. This study represents three-dimensional turbulent flow characteristics around a small-sized axial fan measured at the ideal design point $\phi$=0.25, which is equivalent to the maximum total efficiency point, by using three dimensional fiber-optic type LDA system. This LDA system is composed of a 5 W Argon-ion laser, two optics in back-scatter mode, three BSAs, a PC, and a three-dimensional automatic traversing system. A kind of paraffin fluid is used to supply particles by means of fog generator. Mean velocity profiles downstream of a small-sized axial fan along the radial distance show that the streamwise and the tangential components exist in a predominant manner, while the radial component has a small scale distribution and shows the inflection which its flow direction is inward or outward. Moreover, the turbulent intensity profiles show that the radial component exists the most greatly among turbulent energies.

Three-Dimensional Noise Analysis of an Axial-Flow Fan using Computational Aero-Acoustics (공력음향학을 이용한 축류홴의 삼차원 소음 해석)

  • Kim, Joo-Hyung;Kim, Jin-Hyuk;Shin, Seungyeol;Kim, Kwang-Yong;Lee, Seungbae
    • The KSFM Journal of Fluid Machinery
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    • v.15 no.5
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    • pp.48-53
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    • 2012
  • This paper presents a systematic procedure for three-dimensional noise analysis of an axial-flow fan by using computational aero-acoustics based on Ffowcs Williams-Hawkings equation. Flow-fields of a basic fan model are simulated by solving three-dimensional, unsteady, Reynolds-averaged Navier-Stokes equations using the commercial code ANSYS CFX 11.0. Starting with steady flow results, unsteady flow analysis is performed to extract the fluctuating pressures in the time domain at specified local points on the blade surface of the axial flow fan. The perturbed density wave by rotating blades reaches at the observer position, which is simulated by an in-house noise prediction software based on Ffowcs Williams-Hawkings equation. The detailed far-field noise signatures from the axial-flow fan are analyzed in terms of source types, field characteristics, and interpolation schemes.

Numerical Analysis of a Tip Leakage Vortex in an Axial Flow Fan (축류홴 익단누설와류의 수치적 해석)

  • Jang, Choon-Man;Kim, Kwang-Yong
    • 유체기계공업학회:학술대회논문집
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    • 2003.12a
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    • pp.404-411
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    • 2003
  • Three-dimensional vortical flow and separated flow topology near the casing wall in an axial flow fan having two different tip clearances have been investigated by a Reynolds-averaged Wavier-Stokes (RANS) flow simulation. The simulation shows that the tip leakage vortex formed close to the leading edge of the blade tip on suction side grows in the streamwise direction. On the casing wall, a separation line is formed upstream of the leakage vortex center due to the interference between the leakage vortex and main flow. The reverse flow is observed between the separation line and the attachment line generated downstream of the trailing edge, and increased with enlarging tip clearance. The patterns of a leakage velocity vector including a leakage flow rate are also analyzed according to two tip clearances. It is noted that the understanding of the distribution of a limiting streamline on the casing wall is very important to grasp the characteristics of the vortical flow in the axial flow fan.

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