Cavitating Jet Research Articles

Processing of magnesium alloy by energy-intensive multifunction cavitation in a strong magnetic field with laser light excitation and associated sonoluminescence

This work developed a novel metal processing technique referred to as laser-assisted magnetic energy-intensive multifunction cavitation. This technology employs a strong magnetic field to focus bubble energy while applying sonic radiation around a waterjet cavitation jet. Individual bubbles in the cavitation cloud undergo repeated isothermal expansion and adiabatic compression, raising the temperature and pressure of the bubbles. In addition, the presence of a magnetic field over the region between the nozzle exit and the cavitation cloud in which cavitation primarily occurs greatly increases the number and energy density of charged bubble collisions based on the Lorentz force acting between the bubbles. The application of laser light to the charged bubble cloud provides multiphoton excitation that increases the charges of the ions within each bubble, leading to more active collisions. This enhanced cavitation treatment technology was applied to AZ31B magnesium alloy and was found to improve the functionality of the metal.

Experimental research on the erosion characteristics of organ-pipe cavitating jet for hydrate-bearing sediments

Cavitating jet is regarded as a promising breaking rate improvement technology in both the marine natural gas hydrate (NGH) fluidization exploitation method and the integrated radial jet drilling and completion method. Experimental studies on the influences of standoff distance, erosion time, inlet flow rate and hydrate saturation on hydrate-bearing sediments (HBS) breakage by organ-pipe cavitating jet (OPCJ) were conducted. The methane HBS synthesized in laboratory were employed as the experimental samples. The breaking effect were evaluated by four quantifiable indicators: erosion pit volume and maximum depth, and jet specific energy and specific cutting energy. Results show that under the same inlet flow rate, the standoff distance and erosion time have significant influences on the erosion pit shape. For the erosion pit volume and depth, the optimal standoff distances are respectively 4 mm and 5 mm (the diameter of nozzle is 1 mm), in which condition the OPCJ efficiencies of erosion and penetration on HBS are greatly improved. The ultimate erosion depth is 215 mm at an inlet flow rate of 0.085 L/s. The critical breaking velocities of OPCJ and conical jet (CJ) on HBS with hydrate saturation of 50% are respectively estimated to be 17.8 m/s and 24.2 m/s. Increasing hydrate saturation significantly decreases the erosion efficiency of OPCJ on HBS. The inlet flow rate is the most significant factor for the erosion pit volume and depth. This study provides a reference on the potential field applications for the NGH fluidization exploitation method and the integrated radial jet drilling and completion method.

Forming analysis of T2 copper foil processed by submerged water jet cavitation

Forming analysis of T2 copper foil processed by submerged water jet cavitation

Impact of Cavitation Jet on the Structural, Emulsifying Features and Interfacial Features of Soluble Soybean Protein Oxidized Aggregates

A cavitation jet can enhance food proteins' functionalities by regulating solvable oxidized soybean protein accumulates (SOSPI). We investigated the impacts of cavitation jet treatment on the emulsifying, structural and interfacial features of soluble soybean protein oxidation accumulate. Findings have shown that radicals in an oxidative environment not only induce proteins to form insoluble oxidative aggregates with a large particle size and high molecular weight, but also attack the protein side chains to form soluble small molecular weight protein aggregates. Emulsion prepared by SOSPI shows worse interface properties than OSPI. A cavitation jet at a short treating time (<6 min) has been shown to break the core aggregation skeleton of soybean protein insoluble aggregates, and insoluble aggregates into soluble aggregates resulting in an increase of emulsion activity (EAI) and constancy (ESI), and a decrease of interfacial tension from 25.15 to 20.19 mN/m. However, a cavitation jet at a long treating time (>6 min) would cause soluble oxidized aggregates to reaggregate through an anti-parallel intermolecular β-sheet, which resulted in lower EAI and ESI, and a higher interfacial tension (22.44 mN/m). The results showed that suitable cavitation jet treatment could adjust the structural and functional features of SOSPI by targeted regulated transformation between the soluble and insoluble components.

The application of a novel hydrodynamic cavitation device to debride intra-articular monosodium urate crystals

IntroductionEfficient and complete debridement of intra-articular deposits of monosodium urate crystals is rarely achieved by existing arthroscopic tools such as shavers or radiofrequency ablation, while cavitation technology represents a prospective solution for the non-invasive clearance of adhesions at intra-articular interfaces.MethodsSimulation modeling was conducted to identify the optimal parameters for the device, including nozzle diameters and jet pressures. Gouty arthritis model was established in twelve rats that were equally and randomly allocated into a cavitation debridement group or a curette debridement group. A direct injection nozzle was designed and then applied on animal model to verify the effect of the cavitation jet device on the removal of crystal deposits. Image analysis was performed to evaluate the clearance efficiency of the cavitation device and the pathological features of surrounding tissue were collected in all groups.ResultsTo maximize cavitation with the practical requirements of the operation, an experimental rig was applied, including a 1 mm direct injection nozzle with a jet pressure of 2.0 MPa at a distance of 20 mm and a nitrogen bottle as high-pressure gas source. With regards to feasibility of the device, the clearance rates in the cavitation group were over 97% and were significantly different from the control group. Pathological examination showed that the deposition of monosodium urate crystals was removed completely while preserving the normal structure of the collagen fibers.ConclusionsWe developed a promising surgical device to efficiently remove intra-articular deposits of monosodium urate crystals. The feasibility and safety profile of the device were also verified in a rat model. Our findings provide a non-invasive method for the intraoperative treatment of refractory gouty arthritis.

Effect of Water Jet Cavitation Peening on Short-Period Oxidation Behavior of Alloy 600 in PWR Primary Water

Water jet cavitation peening (WJCP) was used to strengthen the surface of nickel-based alloy 600. Residual stress, hardness, surface roughness, microstructure, and short-period oxidation behavior in untreated (UT) and WJCP-treated alloy 600 were characterized. A continuous oxide film was formed on the WJCP-treated surface after a short period of exposure, while it was discontinuous in the UT specimen. The change in oxidation behavior was attributed to the ultrafine grain and dislocation structure resulting from the WJCP treatment.

Material Removal Characteristics of Spherical-Array-Focused Ultrasonic Abrasive Machining.

To improve the ultrasonic energy and realize far-field ultrasonic abrasive machining of complex surfaces, a spherical-array-focused ultrasonic abrasive machining system was established. By combining ultrasonic field simulation, detection and a single-factor experiment, the influences of the ultrasonic generator current, abrasive concentration, and particle size on the material removal properties and surface quality evolution of quartz glass were investigated. When the current was less than 0.4 A, the material removal showed plastic removal at the nanoscale. When the current was more than 0.5 A, the cavitation phenomenon formed micron-scale impact removal traces on the workpiece surface. The increase in abrasive concentration increased the impact density and material removal rate, while excessive abrasive concentration increased the impeding effect between abrasive particles and reduced the material removal rate. Moreover, the increase in abrasive particle concentration enhanced heterogeneous cavitation nucleation, promoted the removal of abrasive impact materials under the action of a cavitation jet, and inhibited the removal of direct surface cavitation. The abrasive particle size affects the heterogeneous cavitation nucleation and the acceleration of the cavitation jet on abrasive particles, which affects the material removal rate and surface quality. By controlling the energy of the focused ultrasound and abrasive parameters, the plastic or brittle domain removal of quartz glass can be achieved at the micro- and nanoscales.

Numerical Simulation of Flow Field of Submerged Angular Cavitation Nozzle

A model of a submerged angular cavitation nozzle is established, which consists of a contraction part, parallel middle part, and expansion part. Based on the CFD technique, a numerical simulation of the flow field of the submerged cavitation nozzle is carried out, in which a multiphase mixture model, cavitation model, and renormalization group (RNG) k-ε turbulence model are applied. Considering the influence of mixture density on cavitation, the effects of the inlet contraction part, parallel middle part, and outlet expansion part on the velocity and vapor volume fraction are studied. The numerical simulation results show that the mixture density is essential in the cavitation jet. When the nozzle diameter d is fixed, the designed angular cavitation nozzle with contraction angle α = 13.5°, parallel middle part length Ld = 3d, expansion part length Le = 4d, and expansion angle β = 60° can effectively bring out cavitation. A cavitation cloud is produced near the rigid wall of the outlet expansion section and diffuses in a vortex ring shape. Optimizing the nozzle structure can improve the cavitation effect of the nozzle. The feasibility of this model is verified by relevant experimental data.

Parametric Studies of Effect of Cavitation Jet Modes on Wear Rate of Surface of Structural Materials

In this study the kinetic curves of cavitation wear of cast steels 20 GL and 30 L used for production of critical elements of hydraulic machines were obtained. The typical predominance of growth rate of cavitation mark diameter over its depth was found on the surfaces of the investigated cast steels. The revealed phenomenon made it possible to offer a formula for estimating the volume removal of the examined cast steels in order to expand the scope of the method according to ASTM G134-17. This method uses profilometry and microscopy and allows to determine cavitation resistance both for homogeneous and heterogeneous materials, including materials after modification of their surface (with different types of coatings and hardenings).

Treatments of orange-spotted grouper (Epinephelus coioides) against Cryptocaryon irritans with •OH, ClO2 or HCHO: Survival, physiological and histological response.

Cryptocaryon irritans causes one of the most serious diseases in various wild and cultured marine fish, leading to mass mortality and economic loss. In this study, hydroxyl radical (•OH) solution produced by strong ionization discharge combined with water jet cavitation effect was injected into orange-spotted grouper (Epinephelus coioides) aquaculture tanks for C.irritans control. The results showed that all C.irritans theronts were inactivated by •OH solution at concentrations of 0.5mg/L within 2min. •OH could induce alteration of shape, the absence of motility and macronucleus dispersion in theronts. A possible explanation was that the macronucleus of C.irritans might be damaged by •OH; as a result, its metabolism and life activities were disturbed. The •OH treatment increased the survival rate of E.coioides challenged with C.irritans from 64.7 ± 8.0% (mean ± SD) to 100% and reduced their infection intensity significantly. Stress response biomarkers such as malonaldehyde, glutathione, glutathione peroxidase, superoxide dismutase (SOD) and catalase levels in the gills of E.coioides at different time points were analysed. The SOD activity in the •OH group first decreased and then recovered to the initial level at the end of the experiment. The other stress response biomarkers had no significant difference from that in the uninfected control group after •OH treatment. Additionally, the gill of E.coioides in the •OH group exhibited slight and reversible transformation compared with the uninfected control group. Compared with •OH treatment, chlorine dioxide and formalin treatment reduced the survival rate, induced oxidative damage and changed the histological gill structure in E.coioides. In conclusion, •OH could be applied effectively to control C.irritans infection without affecting the normal physiological condition of E.coioides.

Effect of water jet cavitation peening on electrochemical corrosion behavior of nickel-based alloy 600 in NaCl solution

Surface roughness, residual stress, grain boundary microstructure of the surface layer, the electrochemical corrosion behavior and the surface chemical state after the electrochemical test in alloy 600 in 3.5 wt% NaCl medium was investigated. After the WJP treatment, the surface roughness was increased and residual compressive stress was introduced. A low angle grain boundary layer and a lamellae-shaped layer were formed on the surface. A passivation film with higher Cr content was formed on the WJP treated surface after the electrochemical test. After the WJP treatment, the electrochemical corrosion potential changed from −151 ± 4.6 mV to −133 ± 3.1 mV, the corrosion current density changed from 0.298 ± 0.003 μA/cm2 to 0.052 ± 0.001 μA/cm2, the pitting potential increased from 258 ± 13 mV to 350 ± 8 mV, and the film resistance increased from 4283 ± 158 Ω/cm2 to 124,850 ± 187 Ω/cm2. The superior corrosion resistance was attributed to the change in stress state and microstructure of the surface layer.

Improving effects of cavitation peening, using a pulsed laser or a cavitating jet, and shot peening on the fatigue properties of additively manufactured titanium alloy Ti6Al4V

To demonstrate and compare the improving effects of cavitation peening and shot peening on the fatigue properties of additively manufactured metals, titanium alloy Ti6Al4V specimens prepared by direct metal laser sintering were treated by cavitation peening, using a pulsed laser or a submerged high-speed cavitating water jet, and shot peening and, subsequently, subjected to torsion fatigue tests. It was revealed that cavitation peening using a laser, shot peening, and cavitation peening using a cavitating jet prolong the fatigue life of AM Ti6Al4V at τa (applied stress) = 450 MPa by factors of 3.5, 3.2, and 1.4, respectively.

Structure influence on the operating limit range and mixing performance of non-axisymmetric jet pump

Although cavitation chocked jet pumps guarantee a steady and accurate liquid mixture, the existing pumps have the shortcomings of big energy loss and small cavitation working range. In the current study, aiming at enhancing the performance of the cavitation mixing devices, an innovative non-axisymmetric jet pump design is proposed. The cavitation characteristics and the mixing performance of the new design have been investigated by both computational simulation and experimental testing. Based on the results of computational fluid dynamics (CFD), it is found that the cavitation on the suction tube side is strengthened due to the turbulence caused by the abrupt change in the local flow channel structure, while the cavitation on the opposite side is weakened due to the gradual flow channel structure. Our experimental testing results prove that our new design can provide a steady mixing ratio as long as the non-axisymmetric vapor cloud steadily covers the suction tube outlet. Furthermore, geometric parameters (convergent angle, divergent angle, throat length and area ratio) of the device have been optimized through the orthogonal analysis. The critical pressure ratio of the optimized device ranges from 0.76 to 0.63 when the critical flow ratio is in the range of 0–10%, which indicates that the optimized device has much less energy loss and a wider working range than the current axisymmetric cavitating jet pumps. Through quantitative energy loss analysis, we have found that the cavitation maintenance corresponds to the greatest energy loss in the jet pumps, yet our non-axisymmetric structure design could effectively reduces energy loss. The current research reveals the physical mechanism on how a non-axisymmetric structure affects the cavitation characteristics as well as the performance of jet pumps.

Structure optimization of the organ-pipe cavitating nozzle and its erosion ability test on hydrate-bearing sediments

Cavitating jet is a promising drilling rate improvement technology in both the marine natural gas hydrate (NGH) fluidization exploitation method and the integrated radial jet drilling and completion method. In present study, we aim to improve the efficiency of jet erosion and extracting NGH. With a computational fluid dynamics (CFD) method, the pressure, velocity and cavitation field characteristics of organ-pipe cavitating jet (OPCJ) are analysed. The divergent angle, throat length, and divergent length of OPCJ nozzle are preferred to obtain stronger jet cavitation erosion effect. Laboratory experiments of gas hydrate-bearing sediments (GHBS) erosion by OPCJ and conical jet (CJ) are conducted to compare and validate the jet erosion performance. The impinging models of OPCJ and CJ are constructed to study the impact characteristics. Results show that the preferred values of divergent angle, throat length, and divergent length are 15°, 1d, and 3d, respectively, in present simulation conditions. For GHBS, the OPCJ possesses the advantages of high efficiency and low energy consumption. Moreover, the OPCJ has higher penetration efficiency, while showing equivalent penetration ability compared to CJ. During the impinging process, the OPCJ can induce stronger impact pressure and turbulence effect, and also shows stronger chambering effect and bottom cleaning ability compared to CJ. This study presents the erosion performance of OPCJ and CJ on GHBS, and provides preliminary insights on the potential field applications in NGH exploitation.

Nozzle resonance mechanism and cooperative optimization of self-excited oscillating pulse cavitation jet

The peak value and pulsation amplitude of the self-excited oscillating pulse cavitation jet nozzle are essential indices to evaluate the jet performance. We established a simulation model of the jet process of the nozzle to investigate the evolution mechanism of the inner and outer flow fields. We used the chamber fillet, chamber diameter, chamber length, and outlet-tube diameter as the design variables, and the peak value of the striking force and the amplitude of the pulsation of the striking force as the target variables. The collaborative optimization design method of the nozzle was determined by combining the orthogonal test method, the back propagation neural network, and the nondominated sorting genetic algorithm. As indicated by the results, when the inlet pressure was 3 MPa, the factors ranked as follows in terms of their effects on the jet performance of the nozzle: the chamber fillet, the outlet-tube diameter, chamber diameter, and the chamber length. To verify the feasibility of the collaborative optimization method, the nozzle was fabricated via 3D printing, and the simulation model was verified by testing. This study provides support to the development of design theory for self-oscillating pulsed cavitation jet nozzles.

Flow-visualization and numerical investigation on the optimum design of cavitating jet nozzle

Cavitating jet is widely used in drilling, rock cutting and ocean resource exploitation because of its strong erosion ability. The analysis of the relationship between the flow characteristics and the structure of cavitating jet nozzle is critical. Here, we utilized 3D printed technology and high-speed photography to design visualization experiments to analyse the impact of the variation of resonator and throat size of the organ-pipe self-resonating cavitating nozzles on the cavitation characteristics through image processing. The velocity field, pressure field and vapor volume fraction injected by the nozzle were taken as the objective functions to study the influence of different structural parameters on the cavitation effect based on FLUENT 19.0 software, and the results were compared with the experimental results. The results show that increasing the length and diameter of the resonator contributes to the occurrence of cavitation and the structure stability of the flow field. However, excessive size affects self-resonant of the nozzle and makes it difficult to form resonance effect. In this study, the optimal values of nozzle throat length and divergent angle are twice the throat diameter and 40°, respectively. This research provides an integrated research method to study the optimization of self-resonating nozzle and cavitating jet characteristics.

Cavitation stripping of graphene by circulating supercritical carbon dioxide jet and its properties

In this paper, graphene was stripped by circulating liquid phase method, supercritical carbon dioxide was selected as stripping agent, and a cavitation device was set on the pipeline to generate supercritical carbon dioxide jet cavitation to strengthen graphene stripping. Using the characteristics of small molecule intercalation and easy separation of scCO2, we succeeded in stripping graphene with fewer layers. With pressure of 10–16 MPa, temperature of 40 °C, time of 1 h, supercritical carbon dioxide circulation flow of 12 L/h, 0.47 mg/ml graphene dispersion can be obtained. Through electron microscope characterization, it can be judged that its ID/IG value was only 0.167, and the proportion of double-layer graphene reached 65%. Using the obtained dispersion to prepare flexible films, graphene films with resistivity of 0.0239 Ω /m, sensitivity of 176 and stable performance after 1000 cycles can be obtained. The advantage of this method was to avoid using expensive organic solvents such as NMP. After jet cavitation strengthening, the efficiency was higher and the conditions were milder than that of the simple supercritical carbon dioxide stripping method, which was conducive to the realization of industrial application.

Turbulence Characteristics in the Mixing Layer of a Submerged Cavitating Jet at High Reynolds Numbers

In this paper, unsteady and time-averaged turbulence characteristics in a submerged cavitating jet with a high Reynolds number are studied using large eddy simulation. The simulation is validated by comparing the vapor distribution using CFD and a high-speed photography experiment. The results indicate that the currently used numerical method can predict the evolution of the cavitation cloud in the jet accurately. The instantaneous and time-averaged flow fields of the submerged jet with three different cavitation numbers are studied. Comparing the frequency spectral of jets with different cavitation numbers, it is found that, for a fixed location, the frequency increases with the decrease in the cavitation number. Comparing the vorticity distribution at different streamwise locations, the instability process of the ring-shapes vortexes is revealed. Comparing the shape of the cavitation cloud and the vortexes in the jet finds that their spatial distribution and the temporal evolution are similar, indicating that the dynamic characteristics of the vortex and the cavitation affect each other. For the currently investigated cavitating jets, the Reynolds number increases with the decrease in the cavitation number. However, the spreading rate is lower for the jet with higher Reynolds numbers here. This is means that the momentum exchange between the jet and submerging water is reduced by the cavitation phenomenon.

Quantitative Evaluation of Submerged Cavitation Jet Performance Based on Image Processing Method

The submerged cavitation jet is suitable for ocean engineering activities such as ship fouling cleaning, organic wastewater treatment, offshore oil drilling, and natural gas hydrate extraction due to its superior hydraulic performance and erosion capacity. As an intuitive analysis method, image processing is widely used to investigate the characteristics of submerged cavitation jets. However, due to the lack of quantitative evaluation of the cavitation cloud in image processing, it is difficult to establish the relationship between cavitation cloud image and cavitation performance. Therefore, a novel image processing method based on dimensionless grayscale intensity is proposed in this paper. This method was used under different sample spaces to obtain the maximum mass loss of the sample. The results showed that the method could accurately calculate the maximum mass loss of the sample based on the image processing results. When the sample space is 200 images and the working pressure is 20 MPa, the calculation error of the image processing method for the maximum mass loss of the sample is 1.26%. For the sample spaces of 10–5000 images, the maximum calculation error of the image processing method for the maximum mass loss of the samples is 3.29%. The image processing method proposed in this paper establishes the relationship between the cavitation cloud image and the maximum mass loss of the samples, which provides help for further understanding and application of submerged cavitation jets.

Study on the influence of active jet parameters on the cavitation performance of Clark-Y hydrofoil

Cavitation is a phase change that severely endangers the safe and stable operation of hydraulic machinery. At present, one of the effective methods to control cavitation is the active jet. However, limited literature reports on multi-parameter optimal control of cavitation flow consider jet direction, flow, and position at the same time. This study attempts to fill this gap by determining the transient interaction mechanism of active jet and hydrofoil cavitation flow and to reveal the relationship between active jet and cavitation development. Clark-Y hydrofoil is taken as the research object and the grey Taguchi algorithm is used to obtain the optimal scheme of lift-drag ratio and hydrofoil ratio. The large eddy simulation combined with the Zwart-Gerber-Belamri cavitation model was used to numerically simulate the orthogonal test program and optimize its performance. Results are as follows: The closer the jet position to the leading edge of the hydrofoil, the easier it is for the active jet to block the back jet, reducing the cavity volume and hydrofoil drag but reducing the lift coefficient; The hydrofoil shows the best hydraulic performance when the jet position and the leading edge of the hydrofoil has a distance x of 0.3L (L is the chord length), the jet ratio u/u0 is 0.3, and the angle θ between the jet and the horizontal plane is 22°; Using the optimal jet scheme increases the lift-drag ratio k of the hydrofoil by 11.43% while the cavitation volume fraction is reduced and only 30% of the original hydrofoil.