Flow visualization and the three-dimensional flow in an axial-flow pump

Zierke, W. C.; Straka, W. A.

doi:10.2514/3.24021

Cited by 27 publications

(22 citation statements)

References 19 publications

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“…In parallel with the present study, You et al (2005) performed a detailed analysis of the vortex-shedding frequency in the blade wake and the space-time correlations of the velocity fluctuations in the endwall tip-leakage flow, and suggested that the tip-leakage vortex is subject to a pitchwise low-frequency wandering motion. Similar observations have been reported by other experimental and numerical studies in tip-clearance configurations (Zierke & Straka 1996;Wang & Devenport 2004).…”

Section: Resultssupporting

confidence: 92%

Large-eddy simulation analysis of mechanisms for viscous losses in a turbomachinery tip-clearance flow

et al. 2007

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The tip-leakage flow in a turbomachinery cascade is studied using large-eddy simulation with particular emphasis on understanding the underlying mechanisms for viscous losses in the vicinity of the tip gap. Systematic and detailed analysis of the mean flow field and turbulence statistics has been made in a linear cascade with a moving endwall. Gross features of the tip-leakage vortex, tip-separation vortices, and blade wake have been revealed by investigating their revolutionary trajectories and mean velocity fields. The tip-leakage vortex is identified by regions of significant streamwise velocity deficit and high streamwise and pitchwise vorticity magnitudes. The tip-leakage vortex and the tip-leakage jet which is generated by the pressure difference between the pressure and suction sides of the blade tip are found to produce significant mean velocity gradients along the spanwise direction, leading to the production of vorticity and turbulent kinetic energy. The velocity gradients are the major causes for viscous losses in the cascade endwall region. The present analysis suggests that the endwall viscous losses can be alleviated by changing the direction of the tip-leakage flow such that the associated spanwise derivatives of the mean streamwise and pitchwise velocity components are reduced.

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Section: Resultssupporting

confidence: 92%

Large-eddy simulation analysis of mechanisms for viscous losses in a turbomachinery tip-clearance flow

et al. 2007

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“…1,2 In a transonic compressor, interaction between passage shock and tip-clearance flow is implicated in the degradation of efficiency as well as vibrations and noise generation 3 while tip-leakage cavitation is induced by the low pressure events in the vicinity and downstream of the tip gap of liquid pumps. [4][5][6][7][8] These issues have motivated a number of experimental and computational investigations where a reduction of the tip-clearance flow related detrimental effects was attempted through the change of tip-gap size. [4][5][6][7][8][9][10][11][12][13][14] In axial compressors, it has been reported that an increase of tip gap between the blade tip and casing wall also increases the size of the tip-leakage vortex and shifts the origin of the vortex further downstream with an increased angle between the path of the tip-leakage vortex center and that of the blade wake.…”

Section: Introductionmentioning

confidence: 99%

“…[4][5][6][7][8] These issues have motivated a number of experimental and computational investigations where a reduction of the tip-clearance flow related detrimental effects was attempted through the change of tip-gap size. [4][5][6][7][8][9][10][11][12][13][14] In axial compressors, it has been reported that an increase of tip gap between the blade tip and casing wall also increases the size of the tip-leakage vortex and shifts the origin of the vortex further downstream with an increased angle between the path of the tip-leakage vortex center and that of the blade wake. 9,10 Storer and Cumpsty 11 employed a compressor cascade with a variety of tip-gap sizes and showed a nonlinear relation of total pressure loss with the tip-gap size, while the size of tip-leakage vortex varied linearly with tip-gap height.…”

Section: Introductionmentioning

confidence: 99%

Effects of tip-gap size on the tip-leakage flow in a turbomachinery cascade

et al. 2006

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The effects of tip-gap size on the tip-leakage vortical structures and velocity and pressure fields are investigated using large-eddy simulation, with the objective of providing guidelines for controlling tip-leakage cavitation and viscous losses associated with the tip-leakage flow. The effects of tip-gap size on the generation and evolution of the end-wall vortical structures are discussed by investigating their evolutionary trajectories and the mean velocity field. The tip-leakage jet and tip-leakage vortex are found to produce significant mean velocity gradients, leading to the production of vorticity and turbulent kinetic energy. Inside the cascade passage, the peak streamwise velocity deficit and magnitudes of vorticity and turbulent kinetic energy in the tip-leakage vortex are reduced as the tip-gap size decreases. The present analysis indicates that the mechanisms for the generation of vorticity and turbulent kinetic energy are mostly unchanged by the tip-gap size variation. However, larger tip-gap sizes are found to be more inductive to tip-leakage cavitation judged by the levels of negative mean pressure and pressure fluctuations.

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“…However, the accurate prediction of viscous flow past a ducted marine proplusor is essential for determining cavitation inception, hydrodynamic forces, and the propulsive performances. The previous works of experiments (Zierke et al, 1995;Zierke and Straka, 1996) and computations (Hassan et al, 1995;Lee et al, 1994;Sheng et al, 1997) have been mostly carried out without the duct, although some panel codes (Kerwin et al, 1987;Kinnas and Coney, 1992;Hughes, 1993) included the duct. The inviscid panel method is efficient and mature method for predicting performances of marine propeller.…”

Section: Introductionmentioning

confidence: 98%