Numerical study on the effect of the tip clearance of a 100 HP axial fan on the aerodynamic performance and unsteady stall characteristics

Lee, Seulgi; Kim, Young Dong; Yang, Hyeon-Mo; Kim, Sung Hoon; Lee, Sangyeol; Lee, Kyoung‐Yong; Yang, Sang-Ho; Choi, Young-Seok

doi:10.1007/s12206-020-1115-2

Cited by 3 publications

(3 citation statements)

References 19 publications

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“…This flow pattern could cause performance degradation in the stalling flow rates and be closely related to noise, vibration, and system instability. In particular, the backflow became more assertive at lower flow rates [13][14][15][16][17]. Here, in the case of centrifugal fluid machinery, the rotating stall may be observed only between the blade passages rather than the inlet passage; this study relates to an axial fan.…”

Section: Introductionmentioning

confidence: 94%

“…3) and were normalized to the fan diameter (D 2 ). The number of fins (13) was not a variable; the number of fins was considered to be more than the number of blades (10) to sufficiently control the unstable flow associated with the backflow from each blade LE and to avoid overlap with the number of blades and guide vanes (11). The ellipse ratio was selected as 1 (semicircle) for both LE and TE, and the angular distribution (h ASF or b ASF ) should not be considered with two-dimensional geometry.…”

Section: Introductionmentioning

confidence: 99%

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Suppression of Stall-Induced Instability and Positive Slope at Low Flow Rates of an Axial Fan With Two-Dimensional Anti-Stall Fin

Kim

Lee²,

Yang

et al. 2022

Journal of Fluids Engineering

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An axial fan in the general industry needs to secure stable characteristics in a wide operating range through an anti-stalling process, concerning its high demands, energy consumption, safety, and lifetime. As a 'simple' and 'original' method to control the stall of an axial fan, two-dimensional plates so-named anti-stall fin (ASF) were attached inside the casing and toward the shaft. The sensitivity analysis for design variables was conducted through the 2k full factorial design method, and the optimization was performed using the response surface method (RSM). In the case of an axial fan without the ASF, the backflow gradually increased in the spanwise direction toward the hub and the streamwise direction to the inlet passage (upstream), as the flow rate decreased, and the rotating stall was developed through the quickening-growing-setting period. However, an ASF-attached axial fan stably recovered performance degradation in the stalling flow rates and allowed to form a negative slope to 0.5F_d. This study was mainly based on numerical simulations, while the performance before/after application of the ASF was validated through experimental tests.

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Suppression of Stall-Induced Instability and Positive Slope at Low Flow Rates of an Axial Fan With Two-Dimensional Anti-Stall Fin

Kim

Lee²,

Yang

et al. 2022

Journal of Fluids Engineering

Self Cite

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show abstract

“…In the lower flow rates of fluid machinery, ‘stall’ is one of the most detrimental phenomena that has various instabilities due to an increase in incidence angle. Based on the theoretical and empirical discussion as well known in our field, unfavorable factors that can be contained in the stalling flow rates are as follows: positive gradients (degradation) on performance curve ( – or – ) 1 , 2 ; backflow and rotating stall inside inlet passage 3 , 4 ; blade fluctuating stress 5 ; pressure fluctuation 6 ; vibration 7 , 8 ; noise 9 , 10 . Here, the backflow should be developed from the blade (rotor) leading edge (LE) and gradually increases in the spanwise and streamwise direction as the flow rate decreases, whereas the intensity for the other factors such as pressure fluctuation, vibration, and noise may not be inversely proportional to the flow rate.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation on functional limitations of the anti-stall fin for an axial fan: one-factor analyses

Kim

Yang

Lee

et al. 2022

Sci Rep

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The stall in an axial fan is directly related to detrimental phenomena such as performance degradation, vibration, noise, and flow instability at low flow rates. As a kind of passive control method to handle the stall, two-dimensional plates so-named anti-stall fin (ASF) were suggested by ourselves and were attached inside the casing. In this study, the ASF's effect on the internal flow pattern was visually investigated in the flow passage, and its tendency was discussed with the performance curve. Subsequently, the ASF's functional limitations for various design parameters, which the ASF can derive aerodynamically, were presented as the primary focus of this study. Each one-factor analysis was performed, and the internal flow pattern was observed in parallel at the point where the ASF lost its function. For the radial length, axial length, number of fins, and positive-tangential angle, the ASF almost retained its function up to the limitation to prevent instability but radically lost its function at a certain flow rate. For the axial gap and negative-tangential angle, the ASF gradually lost its function. Mostly, this study was based on numerical analysis, and the performance was validated through experimental tests.

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Numerical simulation of aerodynamic noise for the two-stage adjustable-blade axial-flow fan

Wang

Sun

et al. 2022

Physics of Fluids

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In this paper, a three-dimensional calculation model of a two-stage adjustable-blade axial-flow fan is established and verified by grid independence and numerical accuracy. The pressure distribution and sound power level distribution characteristics of the blade surface are explored with variable blade installation angles. Based on the Q-criterion, the study reveals the spatial distribution of the channel and trailing edge shedding and channel vortexes in the flow field. Then, the evolution laws of the fan's aerodynamic noise sound pressure level are also investigated, and its frequency domain characteristics with variable blade installation angles are obtained. The results show that when the rotor blade installation angle is -5{degree sign}, the front-guide vane matches the installation angle of the first-stage impeller. The upper limit of sound power level is the smallest with variable blade installation angles, which is 123.56 dB. Meanwhile, the number and size of vortex structures in the front-guide vane area are the smallest, and the turbulent flow in the flow field is moderate. As the moving blade installation angle is deflected from -10{degree sign} to 10{degree sign}, the total sound pressure level of aerodynamic noise at each component of the fan first decreases and then increases. The minimum value is 121.40 dB and 128.40 dB at the inlet and outlet when the blade installation angle is -5{degree sign}. In addition, the number of eddies periodically shed in the fan flow field is the least. This research can supply technical support for the noise reduction of the two-stage adjustable blade axial fan.

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Numerical study on the effect of the tip clearance of a 100 HP axial fan on the aerodynamic performance and unsteady stall characteristics

Cited by 3 publications

References 19 publications

Suppression of Stall-Induced Instability and Positive Slope at Low Flow Rates of an Axial Fan With Two-Dimensional Anti-Stall Fin

Suppression of Stall-Induced Instability and Positive Slope at Low Flow Rates of an Axial Fan With Two-Dimensional Anti-Stall Fin

Numerical investigation on functional limitations of the anti-stall fin for an axial fan: one-factor analyses

Numerical simulation of aerodynamic noise for the two-stage adjustable-blade axial-flow fan

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