Dynamics of the supercavitating hydrofoil with cavitator in steady flow field

Khoo, Boo Cheong

doi:10.1063/5.0030907

Cited by 24 publications

(2 citation statements)

References 53 publications

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“…Passive control was observed to reduce the dominant frequency of pressure pulsations. 179 Xu et al 180 used cavitators placed at various locations on a hydrofoil's bottom surface to study the supercavitation flow around it. As their observations showed, a localized high-pressure region appears between the leading edge of the hydrofoil and the cavitator, and downstream of the cavitator, the pressure is equal to the saturated vapor pressure of water.…”

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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Section: Physics Of Fluidsmentioning

confidence: 99%

Cavitation control using passive flow control techniques

et al. 2021

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“…When the underwater projectiles travel at a high speed, and the water pressure near the projectile body decreases and reaches the saturated vapor pressure, the surrounding liquid occurs the phase change and forms the cavity. [1,2] As the projectile's velocity continues to increase, the cavity enlarges and completely envelops the projectile body, which becomes a supercavity. At this point, the vapor contacts the projectiles instead of water, greatly reducing the drag force experienced by the projectile.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Cavitation and Hydrodynamic Characteristics of Supercavitating Projectiles in the Shear Flow

Yuan

Zhao

Zhou

et al. 2023

J. Phys.: Conf. Ser.

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To investigate the cavitation and hydrodynamic characteristics of supercavitating projectiles in the shear flow, the Mixture multiphase and Schnerr-Sauer cavitation models are employed to simulate the underwater projectiles. The inflow average velocity is 600 m/s, and the shear rates range from 0 to 7500 s−1. In the uniform flow, the supercavity enveloping projectiles is vertically symmetrical. The drag is dominated by pressure drag, and the lift coefficient is 0. However, the supercavity is asymmetric in the shear flow, which deviates towards the low-speed side of projectiles. This is because the flow around projectiles runs faster on the high-speed side, and the vortices on the low-speed side entrain more fluid from the high-speed side. Thus, the projectiles suffer from normal shear stress orientating towards the low-speed side, and the lift coefficient turns negative. When the shear rate further increases, the projectile shoulder contacts water on the high-speed side, and the viscosity around projectiles is enhanced, resulting in the significant augmentation of the drag coefficient. As the water pressure is strongly larger than saturated vapor pressure on the low-speed side, the normal component of pressure acts more intensely towards the low-speed side of projectiles, and the lift coefficient is further decreased.

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