Impact Of Liquid Jet Research Articles

Study on the Stress Distribution Characteristics of Rock in the Bottomhole and the Influence Laws of Various Parameters Under the Impact of a Liquid Nitrogen Jet

This study presents research on the stress distribution characteristics of rock in the bottomhole and the influence laws of various parameters under the impact of liquid nitrogen jet. A multi-field coupled numerical model considering transient flow field, conjugate heat transfer, and nonlinear solid deformation was established to investigate the damage-induced fracturing mechanism of rock under liquid nitrogen jet. The study compares the impact effects of liquid nitrogen jet and water jet on rock and analyzes the variations in the stress field under different parameters. Due to its extremely low temperature, the liquid nitrogen jet creates a strong thermal stress gradient in a short time, significantly increasing the maximum principal stress and Mises stress in the rock compared to a water jet. Solid parameters, particularly the confining pressure and elastic modulus of the rock, have a more significant impact on stress distribution, while fluid parameters such as outlet pressure and fluid temperature have a smaller and more volatile effect. An increase in confining pressure inhibits tensile failure in the rock, while a higher elastic modulus enhances both tensile and shear failure. The initial rock temperature significantly affects the stress distribution, with optimal tensile failure observed at intermediate temperatures. The liquid nitrogen jet achieves a higher maximum velocity and overflow velocity than the water jet, contributing to more effective rock fracturing. The results provide a theoretical basis for the optimization of liquid nitrogen jet drilling parameters, which can help improve drilling efficiency.

High-Speed Stress Field Measurement In A Soft Substrate During Droplet Impact

In this study, we utilized high-speed photoelastic tomography to quantify dynamic stress fields within a soft substrate during droplet impact. This manuscript details the measurement technique, which employs a high-speed polarization camera and the principles of photoelastic tomography. Our method successfully enabled the quantitative measurement of dynamic stress fields in a soft substrate during droplet impact. Additionally, we conducted an analysis of the impact force derived through the spatial integration of the measured stress field. The discussion explored the interplay between the maximum impact force, droplet viscosity, and substrate elasticity. Our findings indicate that the maximum impact force 𝐹max can be expressed as a function with a self-similar variable of 𝑅𝑒 / 𝐶𝑎^2 , where 𝑅𝑒 is Reynolds number representing the droplet inertial force and droplet viscous force and 𝐶𝑎 is Cauchy number representing the ratio of the droplet inertial force and substrate elastic force. This combination, 𝑅𝑒 / 𝐶𝑎^2 , represents the relationship between the relaxation time of droplet and substrate deformation ( 𝜂/ 𝐸), the contact time of the droplet (𝑅 / 𝑉), and the ratio of substrate elastic force to droplet inertial force. Consequently, the maximum impact force 𝑅𝑒 / 𝐶𝑎^2 is determined by the balance between the relaxation and contact times. We believe that our developed method will significantly enhance the understanding of droplet impact phenomena. Furthermore, it holds potential for broader applications in various engineering processes, such as analyzing stress distribution in materials caused by liquid jet impact and studying cavitation bubbles in viscoelastic materials. This method's ability to provide detailed quantitative measurements of dynamic stress fields offers a valuable tool for future research and technological advancements in related fields.

Dynamic behaviors of cavitation bubbles near biomimetic surfaces: A numerical study

This work is devoted to numerical studies of dynamic behaviors of underwater cavitation bubbles and the associated fluid flow phenomena such as high-speed liquid jet and pressure loads characteristics near biomimetic shark skin surfaces. Potential damages to the surface caused by cavitation bubbles are numerically quantified by the pressure peak, pressure duration and pressure impulse at the surface center. This work utilizes a compressible VOF multiphase model in conjunction with user defined functions (UDFs). The model has been validated against published experimental data in terms of bubble morphological evolution and the time-dependent liquid film thickness. The results reveal that the shark skin-inspired surfaces have important influence on bubble dynamics, water jets and shock wave pressures under various stand-off parameters. Violent deformation and splashing of the bubbles with weak liquid jet impact and pressure impulse can be observed on the surface covered with triangular shaped structures, accompanied by a certain degree of attenuation on the impacting strength and range of the shock waves. Additionally, the migrating and coalescing behaviors of bubble pairs are reduced with the increase of the initial interbubble distance. The large bubble–wall distance can considerably alter the direction of the microjet flow away from the shark skin-inspired surface. These findings shed the light for designing and controlling of multiple cavitation bubbles collapse near biomimetic surfaces of high-speed marine applications.

Study on film spreading from rectangular liquid jet impact

Study on film spreading from rectangular liquid jet impact

Experimental investigation of impact force variations during high-speed liquid impingement erosion

High-speed liquid impingement erosion occurs in many industrial settings. The erosion transition, which occurs after the incubation period of liquid impingement erosion, significantly changes the erosion behavior, such as the material erosion rate and surface roughness; however, when and how the transition occurs remains elusive. The study focused on the impact force exerted on a material by a liquid jet impact during the transition in high-speed liquid impingement erosion. To this end, the force acting on an aluminum specimen attached to a force sensor during liquid impingement erosion was examined experimentally. The critical condition, which indicates the beginning of the accumulation stage of erosion, was detected through mass-loss measurements and visual observation of the target material. The results demonstrated a distinctive transition in the impact force with respect to the exposed flow volume. Additionally, a dynamic mode decomposition technique was employed to analyze variations in the impact force. Finally, the mechanism underlying the long-term variation in the impact force was discussed, and the correlation between the impact forces and erosion depths during high-speed liquid impingement erosion was presented.

Effects of nozzle orifice shape on jet breakup and splashing during liquid jet impact onto a horizontal plate

In some accident situations in nuclear power plants, liquid coolant is discharged from a non-circular rupture hole. Thus, to improve the understanding on the effects of nozzle orifice shape on the jet behavior, experiments were carried out on the liquid jet ejected from oval nozzles. In the experiments, water was used as the test liquid, the area-equivalent nozzle diameter was within 1.8-2.9 mm, the aspect ratio of the nozzle hole was within 2.6-4.8, and the jet velocity was varied within 0.25-11.3 m/s. At low and high liquid flow rates, the liquid jet behaved similarly to the circular jet; the jet breakup lengths and the size of the droplets formed after the jet breakup were expressed by similar dimensionless correlations as those for the circular jet. At the intermediate liquid flow rate, a bamboo leaf-like structure formed on the liquid jet dominated the jet breakup. The jet breakup length was therefore correlated using a theory for the surface tension-induced shape oscillation of elliptical fluid. These correlations enabled to estimate the liquid jet state at any distance from the nozzle. It was also confirmed that if the state of the liquid jet at the impact point is known, the splash rate and the size of the splashed droplets can be predicted satisfactorily using the available correlations based on the experimental data for the circular jet. Therefore, the present work extended the available knowledge on the liquid jet discharged from a circular nozzle to enable the prediction of the behavior of the liquid jet and the characteristics of the secondary droplets produced during liquid jet impact onto a solid surface for the oval nozzles.

Transient cooling experiment of laminar jet impacting on cylinder

Liquid jet impact cooling is found in many industrial applications. In transient process of liquid jet impacting on surface, there are correlations among liquid film flow, heat transfer regime and surface temperature when phase transition is involved. Aiming at application scenarios of laminar jet impacting on cylindrical cooling targets, an experiment of laminar jet impacting on cylinder was performed to investigate transient cooling characteristics featured by temperature dropping curves. Liquid film evolutions were acquired by high-speed camera, while surface temperatures were monitored by thermocouples, and effects of jet outlet velocity u (outlet Reynolds number Re) and impact height H were explored. Results reveal that, transient process of jet impact is categorized into non-wetted (film boiling, duration of τ1), developing wetted (mainly transition boiling and nucleate boiling, duration of τ2) and fully wetted stages (mainly non-phase transition convection). Among them, τ1 and τ2 are decreased with rising of Re. Jet exhibits steady, perturbed and fractured states at different H. When u = 0.44 m/s (Re = 680), for steady state jet, τ1 decreases from 119 s to 103 s, while variation of τ2 is insignificant as H increases from 27 mm to 37 mm. When jet is unstable (H = 42–47 mm), τ1 drops remarkably while τ2 rises with increasing H. Effect of H on temperature dropping curves is weakened with increasing Re. Unlike cases of liquid impacting on flat surface, there are clear distinctions in durations of each transient stage, and there is a secondary inflection point for surface temperature variation in present experiment due to secondary mixing of liquid film.

Corner universality in polygonal hydraulic jumps

Experiments show that vertical liquid jet impact on a solid plate creates a hydraulic jump which takes on a stable polygonal shape with sharp corners. The corner shape exhibits a striking universality that is characterized by the radius of curvature and corner angle at the tip, which remains nearly constant over a wide range of flow conditions. Knowledge of the corner angle allows one to determine the global jump shape, as defined by a dimensionless geometry number related to the isoperimetric inequality, thus giving a complete description of the jump shape.

Experiment on liquid film flow and heat transfer of laminar liquid jet impacting on cylindrical surface

Laminar liquid jet impact has good heat transfer performance with low impact stress on targets. In order to explore the liquid film flow and heat transfer under laminar liquid jet impact on a cylindrical surface, first the flow of a liquid film was analyzed visually; then, the local convective heat transfer characteristics on the cylindrical surface at different impact heights and outlet Reynolds numbers (Re) were obtained by a combination of direct measurement and numerical simulation, followed by a comparative analysis with continuous droplets impacting on the cylindrical surface. The results show that according to flow behavior of the liquid film along the circumferential direction, circumference can be classified into stagnation, thin liquid film, hydraulic jump, stable flow path, and dripping regions. Local convective heat transfer coefficient first drops and subsequently increases marginally along the circumferential direction, while decreasing monotonically along the axial direction. The effect of impact height and outlet Re on local convective heat transfer coefficient is manifested mainly in stagnation, thin liquid film, and hydraulic jump regions. For outlet Re = 984, as impact height rises to a certain degree, there are apparent enhancements of the liquid film perturbation and convective heat transfer performance. Finally, the local Nusselt number correlations in different circumferential regions were proposed.

Aerosol generation by liquid jet impingement onto a solid surface

Liquid jet impinging onto a surface occurs in many industrial process such as nuclear facilities where a part of radioactive material is handled in liquid form. In the case of accidental leak of this liquid, the airborne particle release, in droplets form, is important to quantify since it is the vector of radioactive air contamination. In the literature, while droplets splashing by drop impact have been extensively studied, only few data are available concerning the airborne particle release fraction and the case of liquid jet impact is even less studied. The purpose of this work is to measure aerosol airborne release when a circular liquid jet impacts a solid surface. We found, when the liquid jet is in the Rayleigh regime, so that the jet is broken into multiple drops before impact, the inertia of the impacting drops influences the amplitude of the aerosols mass size distribution but does not change its shape and consequently the aerodynamic mass median diameter. We also show that particle airborne release depends on the impacting Weber and Ohnesorge numbers through the so-called splashing number K which characterizes the splashing transition. We finally propose a quantitative prediction of the aerosol airborne release fraction, valid for Re ∼ O(103−104) and We ∼ O(102−103), opening the way to a more general model.

Non‐damage deep etching of SiC by hybrid laser‐high temperature chemical processing

AbstractSiC is considered as preferred material for micro‐electro‐mechanical system in the future. The excellent mechanical property and chemical stability make it difficult to perform deep etching. The hybrid laser‐high temperature chemical etching is investigated to realize non‐damage deep etching of SiC. The influences of defocus, laser pulse interval, laser intensity, and pulse number on etching depth are researched. The optimized laser parameter for SiC non‐damage deep etching is laser intensity of 10 × 109 W/cm2 with a pulse interval of 10 ms. In order to analyze the interaction mechanism, the temperature field and laser‐induced liquid jet in the liquid environment are calculated numerically. It is concluded that the material removal mechanism consists of laser heating vaporization during laser pulse, mechanical effect of laser‐induced liquid jet impact between two adjacent laser pulses and chemical etching in laser‐induced local high‐temperature environment. The chemical reaction between SiC and mixture of HF, and HNO3 solution produces gases and fluosilicic acid and effectively reduces the roughness of the modified layer making the surface smoother, and also removes the microcracks on the side wall of the etched region.

Classification of ablation mode during impact of hot liquid jet on a solid

The ablation consecutive to hot jet impingement is a safety issue for future Sodium Fast Reactors (SFR) core-catcher that can occur during relocation of molten fuel (corium) under severe nuclear accident situation. Much is still unknown on the ablation phenomenon especially explanations on cavity shape are lacking. However, these data are required to specify the core-catchers which will be used in future nuclear reactors’ vessel to prevent the corium from drilling through the confinement vessel during severe accident. To tackle this subject, data from experiments are obtained and analyzed to identify first order physical mechanisms at stake, and their links to geometry of the cavity. Two ablation mechanisms are noticed, the film ablation regime, for which liquid exits the cavity as a liquid film followed by the pool effect for which the cavity is filled with liquid. The analysis of results shows that the cavity shape is fixed during the film ablation regime and translates as ablation proceeds. Modes of liquid exit from the cavity are analyzed as well as the shapes the cavity assumes. Liquid/air interface temperature is also determined, in the film ablation regime. An explanation of cavity shape is presented. Conditions based on dimensionless numbers are put forward to differentiate between different cavity shapes and liquid exit modes. A first model for transition between film and pool effect ablation regimes is presented. It is the first time to the best of our knowledge that such analyses are undertaken. These give new tools for ablation risk assessment.

Jet Impact on Superhydrophobic Metal Mesh.

Liquid-jet impact on porous, relatively thin solids has a variety of applications in heat transfer, filtration, liquid-fuel atomization, incontinence products, and solid-substrate erosion, among others. Many prior studies focused on liquid-jet impact on impermeable substrates, and some have investigated the hydraulic jump phenomenon. In the present work, the liquid jet strikes a superhydrophobic, permeable, metal mesh orthogonally, and the radial spreading and throughflow of the liquid are characterized. The prebreakthrough hydraulic jump, the breakthrough velocity, and the postbreakthrough spatial distributions of the liquid are investigated by varying the liquid properties (density, surface tension, and viscosity) and the openness of the metal mesh. The hydraulic jump radius in the prebreakthrough regime increases with jet velocity and is independent of the liquid properties and mesh geometry (pore size, wire diameter and pitch). The breakthrough velocity increases with surface tension of the liquid and decreases with the mesh opening diameter and liquid viscosity. A simple analytical model predicts the jet breakthrough velocity; its predictions are in accordance with the experimental observations. In the postbreakthrough regime, as the jet velocity increases, the liquid flow rate penetrating the mesh shows an initially steep increase, followed by a plateau, which is attributed to a Cassie-Baxter-to-Wenzel transition at the impact area of the mesh.

Influence of a Liquid Film Covering a Solid on Liquid Jet Impact Against Its Surface

The impact of a cylindrical liquid jet with a hemispherical tip on an elastic-plastic body uniformly covered in the impact domain by a liquid film has been studied, depending on the thickness of the film. The jet is directed orthogonally to the body surface, which is plane. The liquid in the jet and the film is water; the material of the body is Monel 400. The radius of the jet is $$R$$ , its velocity is $$V=300$$ m/s. The film thickness $$d$$ is varied in the range $$0-0.2R$$ . The action of the jet is considered until it becomes nearly stationary. A similar configuration can occur during the collapse of cavitation bubbles nearby a solid. The dynamics of the liquid (in the jet and the film) and the surrounding gas is calculated by the CIP-CUP method without explicit interface tracking using dynamically adaptive Soroban grids. The body is modeled by an ideal elastic-plastic semi-space, in which the deformations are considered to be small; the plasticity effect is realized according to the Mises condition. The dynamics of the body is calculated by a UNO-modification of the Godunov method of the second order of accuracy. Some features of the body surface loading and the corresponding response of the body (the deformation of its surface, the changes in its stress state) resulting from varying the liquid film thickness have been revealed. It is shown, in particular, that the body surface pressure profiles, initially very different for various $$d$$ , after the time moment $$t\approx R/V$$ become approximately the same (with a small exception at the periphery) and closely correspond to the profile arising under the stationary action of a similar jet of incompressible liquid. The jet impact results in the formation of a very shallow pit on the body surface (with a depth of about $$10^{-3}R$$ ). At $$d=0$$ , the depth of the pit in its center is approximately two times greater than at $$d=0.2R$$ .

Influence of the Initial Shape of a Gas Bubble on Its Dynamics near a Wall under Acoustic Excitation

Influence of initial non-sphericity of a gas bubble on its dynamics at various distances from a plane rigid wall under harmonically varying liquid pressure is investigated. The initial shape of the bubble is taken to be a spheroid with the axis of symmetry orthogonal to the wall. The liquid pressure is varied with the own frequency of the radial oscillations of the bubble in the absence of the wall, beginning with the negative acoustic pressure phase. The liquid is ideal and incompressible, its flow is potential. The velocity of the bubble surface is determined by the boundary element method, its displacement is calculated by the Euler method. It is shown that under the adopted conditions, the bubble collapses either with its transformation into a toroidal one, as a result of impact of the cumulative liquid jet on the bubble surface part close to the wall, or with its disintegration into two smaller bubbles, which results from closing of a narrow neck formed by the bubble surface in the vicinity of the axis of symmetry. Some features of the influence of the initial non-sphericity of the bubble on the shape of the jet, the velocity of its tip and the pressure inside the bubble at the moment of the jet impact on the bubble surface part close to the wall are determined.

The circular capillary jump

In this paper we re-examine the flow produced by the normal impact of a laminar liquid jet onto an infinite plane when the flow is dominated by surface tension. Over the range of parameters we consider, which are typical of water from a tap over a kitchen sink, it is observed experimentally that after impact the liquid spreads radially over the plane away from the point of impact in a thin film. It is also observed that, at a finite radius, there is an abrupt increase in thickness of the film which has been identified as a hydraulic jump. Once the jump is formed this radius remains constant in time and, further, is independent of the orientation of the surface showing that gravity is unimportant (Bhagat et al., J. Fluid Mech., vol. 851, 2018, R5). We show that the application of conservation of momentum in the film, subject only to viscosity and surface tension and ignoring gravity completely, predicts a singularity in the curvature of the liquid film and consequently a jump in the depth of the film at a finite radius. This location is almost identical to the radius of the jump predicted by conservation of energy and agrees with experimental observations. We also provide the correct boundary condition to be applied at an interface, where there is a change in interfacial area as a result of the fluid flow, that accounts for the energy change associated with fluid molecules’ exchange between the interface and the bulk.

Characteristics of Splash Formed by the Impact of Liquid Jet on a Thin Liquid Film

For rotary cup granulation, the splash may occur during liquid slag falls onto the cup, which increases the risk of operation. By performing experiments for three liquids with different properties, including water, 95% ethanol and 30% glycerol-water solution, the characteristics of splash formed by the impact of liquid jet on a thin liquid film were studied. The experimental results showed that increasing the impact velocity and diameter leaded to intense splash, while increasing the viscosity and the surface tension reduced the scale of the splash.

Liquid jet impact on a wet wall

Abstract The impact of an axisymmetric liquid jet on a flat rigid wall wet with a thin film of the same liquid is numerically studied, using the two-dimensional Euler equations with axial symmetry solved by CIP-CUP method. The main attention is paid to the film effect on the liquid pressure field and the wall pressure load for the impact velocities 150 − 350 m/s. Such a velocity range is important for applications related to liquid and cavitation damage and erosion. Small film thicknesses up to 1/5 of the jet radius are considered because they may result in high pressure load on the wall, comparable to that in the dry wall case. The initial most intense period of the impact is investigated. The results show that for the film thickness up to about 1/10 of the jet radius throughout the impact-velocity range considered, a pressure peak appears at the periphery of the loaded zone on the wall, which is similar to the dry wall case. For sufficiently thin films and large impact velocities, the peripheral pressure peak may exceed the water hammer pressure. With increasing the film thickness, the wall-pressure distribution becomes more uniform, the maxima of the wall pressure in the center and at the periphery of the loaded area decrease. Unlike the dry wall case, the level of the wall pressure in terms of its ratio to the water hammer pressure lowers with decreasing the impact velocity because of an increase in the curvature of the shock wave incident on the wall. Rather large negative pressures arise in a small liquid zone near the wall as the expansion wave, generated by interaction between the shock wave and the film surface, reflects from the wall. With increasing the film thickness or lowering the impact velocity, their magnitude decreases. The dependences of the maximum average and maximum local wall pressure on the film thickness and the impact velocity have been determined. The impact of the jet without allowing for its axial symmetry has also been considered. It is found that the neglect of the axial symmetry may significantly reduce the damping effect of the film. With decreasing the film thickness and increasing the impact velocity, the reduction gradually vanishes.

Influence of a Thin Liquid Layer on the Impact of a Jet upon a Wall

The numerical results of studying the impact of an axisymmetric liquid jet upon a flat rigid wall covered by a layer of similar liquid are presented. Primary attention is paid to the effect the layer thickness on the wall has on loading in the range of impact velocities 150–350 m/s. The loading character is studied, and the estimations of wall pressure are obtained in the case of a small layer thickness, which are topical for the applications associated with the droplet and cavitation erosion. It is shown that under the conditions considered the known results of two-dimensional modeling overestimate the maximum of the average pressure on the wall by 1.8 times.

Liquid Jet Impact on the Surface of Metal Alloys

A mathematical model and computational results on dynamics of an elastic-plastic body under impact of a high-velocity liquid jet with a hemispherical end are presented. The body is simulated by an isotropic semi-space; the von Mises condition is used to describe its plastic states. Stresses arising in the surface layer of the body and the deformations of its surface are studied, depending on the material of the body. The study is carried out in the axisymmetric problem statement using a UNO-modification of the Godunov method, which is of the second-order of accuracy both in space and time. The loaded area of the body surface is a circle the radius of which quickly increases from zero. The pressure in the loaded area is spatially and temporally non-uniform. Bodies of three metal alloys are considered, namely, of aluminum, Monel 400, and steel. The loading of the body surface in all three cases corresponds to impact of a water jet at a velocity of 250 m/s. It is shown that under such impact, short-term yield zones arise in the surface layer of the bodies, and a nanoscale pit appears on the body surface in the center part of the impact area. The influence of the body material on the size and configuration of the yield zones as well as the pit profile and its maximum depth is presented.