Demonstration of Leakage Flow Distribution of an Axial Fan inside the Tip Clearance Gap

Gamil, Abdelaziz A. A.; Teixeira, Joao Amaral; Addali, Abdulmajid; Alhajeri, Hamad M.; Elasha, Faris

doi:10.2514/6.2017-1012

Cited by 2 publications

(2 citation statements)

References 9 publications

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“…It has been proved by a considerable number of studies that this tip gap has a vital influence on the energy performance in several types of turbomachinery. [9][10][11][12] The pressure difference offers the driving power for the tip clearance leakage flow released from the tip clearance region. As it is known, the complex vortex structures is the main reason causing unstable operation of the centrifugal pump, and it also has a significant effect on the hydraulic losses affecting the pump performance.…”

Section: Introductionmentioning

confidence: 99%

Effect of tip clearance flow on pressure oscillation and vortex patterns of a high-speed centrifugal pump

Tang

Jiang

Zhang

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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In a micro centrifugal pump with tip clearance working at high speed, the pressure fluctuation and complex vortex structures related to the tip leakage flow are conducted. The external characteristics calculated by the numerical simulation and experiment method agree well, and the maximum deviation of the simulated pump head and efficiency compared with the experimental data is less than 5%. The vortex structures induced by the tip clearance flow, which is less influenced by the flow conditions, can be divided into four categories, namely backflow vortex, passage vortex, primary tip clearance flow (PTLV), and separation TLV (STLV). The evolution of these vortex structures is described by the relative vorticity transport equation, using the relative vortex stretching, Coriolis force, and viscous diffusion. The PTLV starts from the corner of blade tip gap near the leading edge (LE), and breaks away into the STLV in the region of 0.7 R* to 0.8 R* owing to the pushing effect of the secondary tip leakage flow. To analyze the leakage flow quantitatively, the relative velocity in the gap region is decomposed. The results show that the local maximal and minimal values of the normal component correspond to the start position of the PTLV and the separation region of the STLV, respectively. Besides, the passage vortex has the greatest contribution to the pressure pulsation of the passage from main blade to main blade (MB). But the dominant frequency of the pressure alterations has little to do with the vortex, and mainly depends on the rotor-stator interaction (RSI) between the impeller and volute tongue. The results could be referred to improve the efficiency and operational stability of the high-speed centrifugal pumps.

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Section: Introductionmentioning

confidence: 99%

Effect of tip clearance flow on pressure oscillation and vortex patterns of a high-speed centrifugal pump

Tang

Jiang

Zhang

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…They found that grooving the fan shroud could have a significant effect on the leakage flow and tip leakage vortex. Gamil et al 15 focused on the flow structure of the leakage flow at different fan flow rates, tip clearances, and fan stagger angles. In their study, they realized that a part of the leakage flow moved from the suction side toward the pressure side of the blade surface at each stagger angle.…”

Section: Introductionmentioning

confidence: 99%

Effect of blade tip grooving on the performance of an axial fan at different tip clearances in the absence and presence of inlet guide vanes

Kharati-Koopaee

Moallemi

2019

Proceedings of the Institution of Mechanical Engineers, Part A:

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This research aims at the numerical study of the blade tip grooving effect on the performance of a ducted axial fan at different tip clearances in the absence and presence of inlet guide vanes. To do this, significant parameters of the fan (i.e. pressure and torque coefficients as well as fan efficiency) comprising single- and double-grooved tips are evaluated and compared with those of the original fan. Validation of the considered numerical model is performed through comparison of the numerical findings with experimental results of a single-stage ducted fan, which comprises a set of 37 guide vane and 24-blade rotor rotating at the speed of 3600 r/min. Results reveal that grooving the blade tip causes the fan parameters to increase and higher fan parameters could be attained adopting single-grooved tip. It is shown that employing grooved blades causes the sensitivity of fan parameters to the change in the tip clearance to diminish. Results exhibit that the impact of grooving the blade on the reduction of sensitivity of fan parameters to the change in the tip clearance for the single-grooved tip in the absence of guide vanes is more remarkable than the other cases and in this case, as the tip clearance increases from the lower to the upper considered value, the decreased percentages in pressure coefficient, torque coefficient, and fan efficiency are 29.8%, 8.9%, and 22.8%, respectively. Numerical findings show that the influence of grooving the blade on the fan parameters in the presence of guide vanes is lower than that without guide vanes and in the presence of guide vanes, the highest average increase percentages in pressure coefficient, torque coefficient, and fan efficiency relative to those of the original fan, which is observed in the single grooved tip, are 3.1%, 1.4%, and 1.7%, respectively.

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Demonstration of Leakage Flow Distribution of an Axial Fan inside the Tip Clearance Gap

Cited by 2 publications

References 9 publications

Effect of tip clearance flow on pressure oscillation and vortex patterns of a high-speed centrifugal pump

Effect of tip clearance flow on pressure oscillation and vortex patterns of a high-speed centrifugal pump

Effect of blade tip grooving on the performance of an axial fan at different tip clearances in the absence and presence of inlet guide vanes

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