Investigation of the Cavitation Within Venturi Tube: Influence of the Generated Vortex

Kozák, Jiří; Rudolf, Pavel; Hudec, Martin; Urban, Ondřej; Štefan, David; Huzlik, Rostislav; Čala, Martin

doi:10.1007/978-981-10-7218-5_73

Cited by 5 publications

(3 citation statements)

References 11 publications

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“…The researchers have introduced many types of approaches to control the unsteady dynamic behaviour of the cavitating flow, like geometrical parameters, the flexibility of foil, and scale factor [24][25][26][27]. However, it is worth mentioning that the impact of dissolved air in the water and ventilation is not negligible.…”

Section: Introductionmentioning

confidence: 99%

Experimental analysis on unsteady characteristics of sheet/cloud cavitating Venturi flow under the effect of dissolved air

2023

Archives of Thermodynamics

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The highly dynamic and unsteady characteristics of the cavitating flow cause many negative effects such as erosion, noise and vibration. Also, in the real application, it is inevitable to neglect the dissolved air in the water, although it is usually neglected in the previous works to reduce the complexity. The novelty of the present work is analysing the impact of dissolved air on the average/unsteady characteristics of Venturi flow by conducting sets of experimental tests. For this purpose, two different amounts of dissolved air at five pressure levels (i.e. five different sets of cavitation numbers) were considered in the study of cavitating flow inside a Venturi nozzle. The fast Fourier transform analysis of pressure fluctuations proved that the shedding frequency reduces almost by 50% to 66%, depending on the case, with adding the amount of dissolved air. However, the reduction of 14% to 25% is achieved by the vibration transducers. On the other hand, the cavity enlarges as well as bubbly flow is observed in the test chamber at a higher level of dissolved air. Furthermore, it is observed that the re-entrant jet, as the main reason for the cavity detachment, is more effective for the detachment process in cases with a lower level of dissolved air, where the re-entrant jet front penetrates more toward the leading edge.

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Section: Introductionmentioning

confidence: 99%

Experimental analysis on unsteady characteristics of sheet/cloud cavitating Venturi flow under the effect of dissolved air

2023

Archives of Thermodynamics

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“…In this case, surface friction is greatly reduced, which can ensure that the underwater vehicle can maintain high speed efficiently, greatly improving its performance [3,4]. However, since the cavity itself is inside the interface of liquid phase and gas phase, the instability of this two-phase flow is obvious [5]. Meanwhile, the environmental pressure of the vehicle is affected by multiple external factors, and there are problems such as perturbation of hydrodynamic coefficients and unknown interaction from wake flow [6].…”

Section: Introductionmentioning

confidence: 99%

Modeling of the Tail Slap for an Underwater Projectile within Supercavitation

Zhao

Lyu

2019

Mathematical Problems in Engineering

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Detailed process of the tail slap for an underwater projectile in supercavitation is studied in this paper. Firstly, the horizontal equation of motion for the projectile and a dynamic model of the projectile’s tail slap are introduced through a mathematical derivation, including a simple harmonic motion model of the projectile within the supercavitation layer and the tail slap reflection movement model inside the cavity. Subsequently, the MATLAB software package is used to model the projectile’s motion. Characteristics for force from the projectile tail on the water layer during a single tail slap and the behavior of the projectile’s angular motion as well as the characteristics of projectile tail motion through multiple tail slaps are investigated. It is found that the force magnitude of the water on the projectile tail decreases gradually while the relative motion angle of the projectile tail into the water layer and the contact time increase obviously as the projectile repeatedly slaps the cavity interface. When the projectile velocity decreases into a certain range, i.e., less than 50 m/s, the contact time of the tail in the water layer increases dramatically, and the supercavitation can tend to collapse and lead to unstable projectile motion. With increasing lateral deviation and angular velocity of the projectile tail, the number of tail slaps and the angle of reflection both increase significantly. In the case of supercavitation, the parameters of different tail slap points tend to be stable with time.

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“…Vortex is known to lead to chiral separation without any chiral selector [33][34][35] due to the different velocities of each enantiomer by imparting molecular helicity that couples to translational motion in vortex, sending enantiomers in opposite directions 36 . Vortex could be involved in Venturi tube by equipping an oblique blade inside 37 .…”

mentioning

confidence: 99%

Prebiotic Asymmetric Synthesis of Ribose by CO2 Reduction in Hydrodynamic Cavitation with Vortex

Fang,

Ding,

Ying

et al. 2024

Preprint

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Prebiotic synthesis is a critical aspect in the origin of life. Especially, D-ribose plays a fundamental role in the RNA world theory as the exclusive sugar for RNA1-3. CO2 is known to be predominant in the primitive atmosphere4-6. However, prebiotic synthesis of ribose from CO2 has never been reported, leaving origin of D-ribose as an unsolved conundrum. Herein, we propose the enantiomeric formation of D-ribose by hydrodynamic cavitation with vortex in the prebiotic world, which was supported by the formation of enantiomeric ribose under the simulated prebiotic condition in the opposite vortices of a Venturi reactor equipped with antipodal oblique blades. Various sugars with total concentration of ~2.46 μM were achieved in the presence of Ca2+, in which ribose is the main component, with an enantiomeric excess (ee) in the range of 30.2-40.2%. Formaldehyde and CH2OH· were formed from CO2 by high temperature and high pressure in hydrodynamic cavitation. Ribose was predicted to be formed by the reaction involving addition of CH2OH· starting from formaldehyde in the presence of Ca2+. Vortex is speculated to be initiating symmetry breaking of ribose due to different yield of each enantiomer, induced by geometric coefficient interaction between the chiral intermediate and vortex. Our findings provide a prevalent possibility for the enantiomeric formation of D-ribose by cavitation with specific vortex in the prebiotic ocean, which implies hydrodynamic cavitation would be one of the important driving forces for origin of life.

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Investigation of the Cavitation Within Venturi Tube: Influence of the Generated Vortex

Cited by 5 publications

References 11 publications

Experimental analysis on unsteady characteristics of sheet/cloud cavitating Venturi flow under the effect of dissolved air

Experimental analysis on unsteady characteristics of sheet/cloud cavitating Venturi flow under the effect of dissolved air

Modeling of the Tail Slap for an Underwater Projectile within Supercavitation

Prebiotic Asymmetric Synthesis of Ribose by CO2 Reduction in Hydrodynamic Cavitation with Vortex

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