Suppressing tip-leakage vortex cavitation by overhanging grooves

Cheng, Huaiyu; Long, Xinping; Wang, Xincheng; Peng, Xiaoxing; Farhat, Mohamed

doi:10.1007/s00348-020-02996-6

Cited by 46 publications

(8 citation statements)

References 53 publications

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“…To control TLV cavitation, overhanging grooves (OHG) were fitted to hydrofoils by Cheng et al 150 A significant improvement in cavitation suppression was observed with the OHG compared to the baseline, conventional grooves and anti-cavitation lip (ACL) with a minimal effect on hydrofoil performance. Effective reduction in the intensity of TLVs and tip-separation vortices was achieved with small gap sizes.…”

Section: Groovesmentioning

confidence: 99%

Cavitation control using passive flow control techniques

et al. 2021

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Passive flow control techniques, and particularly vortex generators have been used successfully in a broad range of aero-and hydrodynamics applications to alter the characteristics of boundary layer separation. This study aims to review how such techniques can mitigate the extent and impact of cavitation in incompressible flows. This review focuses first on vortex generators to characterize key physical principles. It then considers the complete range of passive flow control technologies, including surface conditioning and roughness, geometry modification, grooves, discharge, injection, obstacles, vortex generators, and bubble generators. The passive flow control techniques reviewed typically delay and suppress boundary layer separation by decreasing the pressure gradient at the separation point. The literature also identifies streamwise vortices that result in the transfer of momentum from the free stream to near-wall low energy flow regions. The area of interest concerns hydraulic machinery, whose performance and life span are particularly susceptible to cavitation. The impact on performance includes a reduction in efficiency and fluctuations in discharge pressure and flow, while cavitation can greatly increase wear of bearings, wearing rings, seals, and impeller surfaces due to excessive vibration and surface erosion. In that context, few studies have also shown the positive effects that passive controls can have on the hydraulic performance of centrifugal pumps, such as total head and efficiency. It is conceivable that a new generation of design in hydraulic systems may be possible if simple design features can be conceived to maximize power transfer and minimize losses and cavitation. There are still, however, significant research gaps in understanding a range of impact factors such as manufacturing processes, lifetime, and durability, and essentially how a static design can be optimized to deliver improved performance over a realistic range of operating conditions.

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Section: Groovesmentioning

confidence: 99%

Cavitation control using passive flow control techniques

et al. 2021

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“…The results show that the strength of TLV changes with the size of tip clearance [5]. At the level of simulation calculation, scholars specifically applied Schnerr Sauer cavitation solid model and Rayleigh Plesset cavitation solid model to carry out simulation research, in order to test the evolution of TLV cavitation flow in detail, and analyze the impact of TLV trajectory and hydrofoil structure on TLV [6]. However, scholars mainly considered the accuracy of numerical calculation methods and the mechanism of TLV cavitation, while ignoring the interaction between tip clearance specifications and TLV cavitation and noise.…”

Section: Introductionmentioning

confidence: 99%

Effect of Tip Clearance Size on the Cavitation Flow and Noise Characteristics of the NACA0009 Hydrofoil

Zhou

2023

J. Phys.: Conf. Ser.

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The noise characteristics of NACA0009 hydrofoil with tip clearance are discussed. Select SST k- ω Turbulence model and Schnerr Sauer cavitation model simulate tip leakage cavitation flow. The results show that the simulation results are in good agreement with the original records, and the tip clearance reduces the energy characteristics of the hydrofoil. With the expansion of tip clearance model, TLV and cavitation compressive strength gradually decrease. In addition, the study of far-field noise shows that the nonspecific curve of the total noise coefficient of far-field noise shows a disc shaped symmetric structure. Compared with the original hydrofoil, when the tip clearance is 20 mm, the far-field dipole noise value at 170 ° angle is reduced by 17.68%. Tip clearance reduces offline and far-field noise. Far field noise decreases with the increase of tip clearance model.

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“…It was found that the sharp tip foil reduced the tip-leakage flow losses and strengthened the separation vortex compared to round tip foil. On the other hand, , Cheng et al (2020), Ye et al (2021) investigated different groove structures applied to the tip, such as the C-type, the overhanging type, and the rectangular type, to suppress the TLV in pumps and pump-jet propulsors. Ji et al (2019Ji et al ( , 2021 investigated a simple way of weakening the TLV of the pumpjet propulsor which is raking the rotor tips towards blade face side in the region beyond 95% tip radius.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Investigation of the Impacts of Rotor Tip-Rake on Excitation Forces of Pump-Jet Propulsors

Ji,

Zhang,

Yang

et al. 2023

Preprint

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The tip-clearance flow in a pump-jet propulsor exerts great impacts on the fluctuating pressures and resultant unsteady forces, which are important sources of structural vibrations and radiated noise underwater. The blade geometry close to the tip is an important factor determining the vortex strength in the tip-clearance flow. In the open-water condition, the effects of raking the rotor tips on duct-surface fluctuating pressures and the resultant unsteady forces acting on different components of the propulsor are investigated via physical model experiments and the numerical solution of Reynolds-Averaged Navier-Stokes equations coupled with the SST k-ω turbulence model. The measured and simulated results of hydrodynamic pressures are consistent to each other, and the simulated flows help better understand why the fluctuating pressures change with the tip geometry. The strong fluctuations of duct-surface pressures are caused by intensive tip separation vortices. The duct-surface pressure fluctuations are effectively reduced by using the rake distribution near the tip towards blade back side and, for the combination of the five-bladed rotor and the seven-bladed stator, the resultant unsteady horizontal (and vertical) forces acting on the duct and stator are also reduced. While increasing rake leads to negative effect on pressure fluctuations and unsteady horizontal (and vertical) forces acting on all the components of the propulsor.

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Suppressing tip-leakage vortex cavitation by overhanging grooves

Cited by 46 publications

References 53 publications

Cavitation control using passive flow control techniques

Cavitation control using passive flow control techniques

Effect of Tip Clearance Size on the Cavitation Flow and Noise Characteristics of the NACA0009 Hydrofoil

Experimental and Numerical Investigation of the Impacts of Rotor Tip-Rake on Excitation Forces of Pump-Jet Propulsors

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