An experimental study of the unsteady characteristics of tip-leakage flow of axial fans with circumferential skewed blades at off-design conditions

Jin, GY; Ouyang, Huajiang; Wu, Yadong; Du, Z-H

doi:10.1177/0957650911404621

Cited by 6 publications

(7 citation statements)

References 16 publications

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“…This seemingly arbitrary motion of the vortex core around its temporarily averaged location is called vortex wandering. The vortex wandering phenomenon for the TLV has been shown with measurement [6,7] and has been reproduced with simulation [8,9] as well.…”

Section: Introduction and Objectivessupporting

confidence: 59%

“…It is clear that the Strouhal number definitions listed above are not equivalent, the numerical value being identical is merely a coincidence. Also, Jin et al [6] reported natural unsteadiness over a wider frequency range, thus, a unique Strouhal number is not straightforward.…”

Section: Resultsmentioning

confidence: 99%

“…The magnitude of the vortex wandering grew continuously along the path of the vortex core. Also, Jin et al [6] reported tip leakage vortex core location displacement of 6.4% of the blade tip chord length at 50% chord length on a plane perpendicular to the chord line.…”

Section: Resultsmentioning

confidence: 99%

“…Jin et al [6] experienced natural unsteady behavior of the TLV in PIV measurements. The vortex cores were identified by local vorticity maximum, the detected cores were randomly scattered in a circle.…”

Section: Introduction and Objectivesmentioning

confidence: 99%

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Application of a higher-order vortex identification method for quantifying the tip leakage vortex wandering in a low-speed axial fan case study

Lendvai,

Benedek

2023

European Conference on Turbomachinery Fluid Dynamics and Thermodynamics

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The natural unsteadiness of turbomachinery tip leakage vortex has been reported in both measurement and simulation. The visualization and quantification of this vortex wandering are challenging using pathlines or simple vortex identification methods. In the present paper, the tip leakage vortex wandering is investigated in the case of a low-speed fan's unsteady Reynoldsaveraged Navier-Stokes simulation. The wandering motion of the leakage vortex is detected by Banks' vorticity predictor -pressure corrector vortex core line localization method. Despite the low computational costs, the simulation predicted the complex vortical structure present in the blade passage. The vortex detection algorithm proved successful in finding the tip leakage vortex, but it failed to follow the core line upon heavy disturbance in the flow. The extent and the frequency of the vortex wandering were determined.

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Section: Introduction and Objectivessupporting

confidence: 59%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introduction and Objectivesmentioning

confidence: 99%

See 2 more Smart Citations

Application of a higher-order vortex identification method for quantifying the tip leakage vortex wandering in a low-speed axial fan case study

Lendvai,

Benedek

2023

European Conference on Turbomachinery Fluid Dynamics and Thermodynamics

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“…In addition, the extremely reduced gaps were a serious handicap for the development of reliable and practicable sensors. Recent investigations have used particle Image velocimetry systems to identify and track the evolution of tip vortex structures in axial turbomachinery (Jin et al, 2011;Miorini et al, 2012;Lee et al, 2019). These investigations have reported notable findings, highlighting the physical mechanisms behind the mixing out of the TLF and analyzing the impact of different parameters, especially the size of the tip gap and the inclusion of tip plates to control the leakage flow (Bae et al, 2005;Aktürk and Camci, 2010;Corsini et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Stator–rotor interaction in the tip leakage flow of an inlet vaned low-speed axial fan

Gonzalez

Meana-Fernández

Fernández

2020

HFF

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Purpose The purpose of the paper is to quantify the impact of the non-uniform flow generated by the upstream stator on the generation and convection of the tip leakage flow (TLF) structures in the passages of the rotor blades in a low-speed axial fan. Design/methodology/approach A full three dimensional (3D)-viscous unsteady Reynolds-averaged Navier-stokes (RANS) (URANS) simulation of the flow within a periodic domain of the axial stage has been performed at three different flow rate coefficients (φ = 0.38, 0.32, 0.27) using ReNormalization Group k-ε turbulence modelling. A typical tip clearance of 2.3 per cent of the blade span has been modelled on a reduced domain comprising a three-vaned stator and a two-bladed rotor with circumferential periodicity. A non-conformal grid with hybrid meshing, locally refined O-meshes on both blades and vanes walls with (100 × 25 × 80) elements, a 15-node meshed tip gap and circumferential interfaces for sliding mesh computations were also implemented. The unsteady motion of the rotor has been covered with 60 time steps per blade event. The simulations were validated with experimental measurements of the static pressure in the shroud of the blade tip region. Findings It has been observed that both TLF and intensities of the tip leakage vortex (TLV) are significantly influenced by upstream stator wakes, especially at nominal and partial load conditions. In particular, the leakage flow, which represents 12.4 per cent and 11.3 per cent of the working flow rate, respectively, has shown a clear periodic fluctuation clocked with the vane passing period in the relative domain. The periodic fluctuation of the TLF is in the range of 2.8-3.4 per cent of the mean value. In addition, the trajectory of the tip vortex is also notably perturbed, with root-mean squared fluctuations reaching up to 18 per cent and 6 per cent in the regions of maximum interaction at 50 per cent and 25 per cent of the blade chord for nominal and partial load conditions, respectively. On the contrary, the massive flow separation observed in the tip region of the blades for near-stall conditions prevents the formation of TLV structures and neglects any further interaction with the upstream vanes. Research limitations/implications Despite the increasing use of large eddy simulation modelling in turbomachinery environments, which requires extremely high computational costs, URANS modelling is still revealed as a useful technique to describe highly complex viscous mechanisms in 3D swirl flows, such as unsteady tip flow structures, with reasonable accuracy. Originality/value The paper presents a validated numerical model that simulates the unsteady response of the TLF to upstream perturbations in an axial fan stage. It also provides levels of instabilities in the TLV derived from the deterministic non-uniformities associated to the vane wakes.

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Numerical investigation of impeller trimming effect on performance of an axial flow fan

et al. 2014

Energy

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An experimental study of the unsteady characteristics of tip-leakage flow of axial fans with circumferential skewed blades at off-design conditions

Cited by 6 publications

References 16 publications

Application of a higher-order vortex identification method for quantifying the tip leakage vortex wandering in a low-speed axial fan case study

Application of a higher-order vortex identification method for quantifying the tip leakage vortex wandering in a low-speed axial fan case study

Stator–rotor interaction in the tip leakage flow of an inlet vaned low-speed axial fan

Numerical investigation of impeller trimming effect on performance of an axial flow fan

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