Analysis of tip-gap size on tip-leakage flow in an axial fan at design and off-design operating conditions

Moghadam, Seyed Mohsen Alavi; Meinke, Matthias; Schröder, Wolfgang

doi:10.29008/etc2019-306

Cited by 2 publications

(3 citation statements)

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“…In order to estimate the order of magnitude of the effect of Re-dependence of C L and C D , the following illustrative example is given. Taking a realistic and representative low-speed axial flow fan 46 as a reference, Re c varies along the blade span within the range of 30000-200000, due to the variation in the chord and in the flow velocity (the latter is also influenced by the rotor speed, 700 to 1400 1/min). Based on Figure 6, this variability in the Reynolds number may cause a variation in C L and C D up to 20% and 30%, respectively, depending on the a angle of attack.…”

Section: Reynolds Number Effectmentioning

confidence: 99%

“…A carefully designed CFD campaign can effectively treat the various effects in a well-distinguished manner. For example, a periodic rotor blade passage is sufficient to be modelled, and centrifugal as well as Coriolis forces can either be taken into account [47] or neglected for judging the significance of the effect of such force fields on the PVS phenomenon. Purposefully selected basic experiments are to be carried out for validating the CFD tools.…”

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confidence: 99%

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Profile vortex shedding from low-speed axial fan rotor blades: a modelling overview

Daku

Vad

2021

Proceedings of the Institution of Mechanical Engineers, Part A:

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This paper presents an overview of the characteristics potentially influencing the profile vortex shedding (PVS) phenomenon being relevant in noise and vibration of low-speed axial fan rotor blades. Dimensional analysis has been applied to explore the essential dimensionless quantities in a systematic and comprehensive manner. On this basis, limitations have been established, and simplifying assumptions have been set up in terms of PVS investigation. Groups of dimensionless characteristics playing a role in the semi-empirical model for predicting the PVS frequency were identified. The available semi-empirical model and its unique features related to the measurement evaluation methodology and Reynolds number dependence have been outlined. The presented comprehensive analysis provides guidelines from the perspective of transferability of the literature data on PVS from steady, isolated blade profile models to low-speed axial fan rotors. It also results in the formulation of objectives of future research related to PVS.

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Section: Reynolds Number Effectmentioning

confidence: 99%

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confidence: 99%

Profile vortex shedding from low-speed axial fan rotor blades: a modelling overview

Daku

Vad

2021

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…Figure 9 illustrates three distinct tip vortex structures, namely the tip leakage vortex (TLV), induced vortex (IV), and tip separation vortex (TSV). Large eddy simulations for a linear cascade in [16] and for an axial fan in [17] have shown similar vortex structures. The most dominant vortex structure is the TLV, which arises due to the tip-leakage jet rolling up from the pressure side (PS) to the suction side (SS).…”

Section: B Effect Of Tip Clearance On Fan Performancementioning

confidence: 82%

On the Fast Prediction of the Aerodynamic Performance of Electronics Cooling Fans Considering the Effect of Tip Clearance

Zhao

Wasala

Persoons

2023

IEEE Trans. Compon., Packag. Manufact. Technol.

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This study aims to complete and validate a recently developed reduced-order model for the fast prediction of aerodynamic performance (P -Q) curve of electronics cooling fans, taking into account the real fan geometry and the tip clearance effect. The effect of tip clearance on tip vortex generation and fan performance was revealed by an experimentally validated 3D computational fluid dynamics (CFD) method. Six different tip clearance ratios ranging from 0% to 12.7% were investigated. The tip clearance was found to have a strong effect on tip vortex generation, which significantly affects the aerodynamic performance of the fan. Fan efficiency increased by up to 7% by reducing the tip clearance ratio by 2.5%. The tip clearance effect was successfully included by the analytical method combined with a correlation equation developed based on the CFD study. The results show that the combined reduced-order model can produce reasonably accurate predictions for fan P -Q curve with errors less than 7.1% compared to CFD results, while having a wide valid range of tip clearance ratio up to 10%. The precision of this model was further validated against experimental results for eight commercial fans. The computational speed of this model is more than three orders of magnitude faster than a steady-state CFD study, making it highly appropriate for fast analysis of fan performance and thermal-flow co-design.

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Analysis of tip-gap size on tip-leakage flow in an axial fan at design and off-design operating conditions

Cited by 2 publications

References 0 publications

Profile vortex shedding from low-speed axial fan rotor blades: a modelling overview

Profile vortex shedding from low-speed axial fan rotor blades: a modelling overview

On the Fast Prediction of the Aerodynamic Performance of Electronics Cooling Fans Considering the Effect of Tip Clearance

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