A review of cavitation in tip-leakage flow and its control

Cheng, Huaiyu; Ji, Bin; Long, Xinping; Huai, Wenxin; Farhat, Mohamed

doi:10.1007/s42241-021-0022-z

Cited by 90 publications

(13 citation statements)

References 144 publications

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“…The main structural components of this centrifugal aerator include an electric pump, impeller, air inlet pipe, and mixing chamber. The centrifugal submersible aerators are of direct-connected construction, simple and compact, capable of withstanding large loads on bearings, with oil-bath rotary shaft seals and air drawn into the impeller chamber to prevent water from coming into contact with the seals during operation, which ensures that they do not need to consider the risk of cavitation and cavitation [18][19][20]. The rotating impeller generates a centrifugal force in the water, through which a negative pressure zone is formed around the impeller, and the air is drawn in through the inlet pipe.…”

Section: Methodsmentioning

confidence: 99%

The Effect of Mixing Chamber Configuration and Submersion Depth on Centrifugal Aerator Performance

Zhang

Zheng

et al. 2022

Sustainability

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Centrifugal aerators are a vital piece of equipment in water treatment. To improve the efficiency and economy of their operation, a study of their mixing chamber structure and submergence depth was carried out using a combination of numerical simulations and experiments. A centrifugal aerator dissolved oxygen (DO) test bench was built and the numerical simulation was compared with the experiment, the inlet air flow rate showing only a 2.23% error, which verifies the reliability of the numerical simulation. The results show that the capacity of oxygen dissolved in the aeration tank increases and then decreases as the relative area ratio (ð) of the mixing chamber increases, reaching the best capacity at ð = 8.38. In the case of different submergence coefficients (β), the gas volume fraction increased by 31.29% on average at β = 0.15; the standard oxygen transfer rate (SOTR) increased and then decreased with the increase of β, with an average increase of 56.6%. Moreover, the oxygenation performance of centrifugal aerators was significantly improved by the reasonable submergence depth and the structure of the mixing chamber.

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Section: Methodsmentioning

confidence: 99%

The Effect of Mixing Chamber Configuration and Submersion Depth on Centrifugal Aerator Performance

Zhang

Zheng

et al. 2022

Sustainability

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“…The casing grooves may also serve as an effective solution for suppressing the tip-leakage vortex (TLV), according to Kang et al 135 and Hah et al 136 It has been confirmed, however, that the effect of passive control strategies in the control of tip leakage is greatly influenced by gap size. 137 The study by Custodio et al 138 focused on the characteristics of cavitation inception with wavy leading-edge patterns. The authors found that hydrofoils with medium and large protuberances can confine the cavitation region behind the protuberance troughs.…”

Section: B Blade Profile and Geometry Modificationmentioning

confidence: 99%

“…Results showed that it is difficult for the ACL to have a satisfactory inhibitory effect on TLV cavitation, and once the vortex generators are not operating under design conditions, a more intense level of cavitation will be induced. 137,176 A recent numerical study by Kadivar et al 177 proposed a new type of VG called cavitating bubble generators (CGs) (Fig. 19).…”

Section: Physics Of Fluidsmentioning

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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“…Cheng et al [6][7] applied LES and Sauer-Schnerr cavitation model to studied the evolution of TLV cavitation and proposed that the non-condensable gas is an important factor to development the TLV cavitation.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of the cavitating flow in an axial flow waterjet pump with special emphasis on the tip leakage flow and tip leakage vortex

Zhao

Chen

Huang

et al. 2022

J. Phys.: Conf. Ser.

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Due to the structural design requirements, tip leakage flow is a common phenomenon in the field of axial flow rotating machinery. The tip leakage flow interacts with the mainstream and induce complex tip leakage vortex. When the local pressure drops to the saturation pressure, cavitation may occur in flow passage and the vortex core. The tip leakage cavitating flow has a huge effect on the flow stability, which may reduce the efficiency of the waterjet pump. In the present study, Zwart cavitation model and SST k-ω turbulence model are employed to simulate the cavitating flow. The new proposed Liutex criterion has been used to capture the vortex structures in the flow passage and the tip gap. The vorticity transport equation in cylindrical coordinates is also used to discuss the variation tendency of the vorticity in the vicinity of the gap region under cavitation condition. The evolution of the cavitation is proved to be vital important for the formation and the breakdown of the tip leakage vortex. By analyzing the vorticity transport equation, the stretching term is shown to be the decisive factor.

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A review of cavitation in tip-leakage flow and its control

Cited by 90 publications

References 144 publications

The Effect of Mixing Chamber Configuration and Submersion Depth on Centrifugal Aerator Performance

The Effect of Mixing Chamber Configuration and Submersion Depth on Centrifugal Aerator Performance

Cavitation control using passive flow control techniques

Numerical analysis of the cavitating flow in an axial flow waterjet pump with special emphasis on the tip leakage flow and tip leakage vortex

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