Cavitating Jet Research Articles

Comparison of the effect of water jet cavitation peening on stress corrosion cracking behavior of nickel-based alloy 600 and alloy 182 in high temperature water

PurposeThis paper aims to understand the effect of water jet cavitation peening (WJP) on stress corrosion cracking (SCC) behavior of alloy 600 and alloy 182 in high temperature water.Design/methodology/approachSurface and cross-section morphology, grain boundary microstructure, residual stress and strain distribution, hardness and surface roughness in water jet cavitation peened alloy 600 and alloy 182 were characterized.FindingsA superior stress corrosion cracking resistance was obtained in 600MA, which can be attributed to the formation of the ultrafine grain layer and the higher magnitude residual compressive stress.Originality/valueRelationship between WJP-induced microstructure and stress state change and SCC susceptibility was conducted. It could provide a theoretical basis for developing application of WJP in nuclear power plants.

Delayed detached eddy simulation and vorticity analysis of cavitating flow around a marine propeller behind the hull

Delayed detached eddy simulation (DDES) together with a homogeneous cavitation model is employed to investigate the cavitating flow around a marine propeller behind the hull. The cavitation influence on the simulation errors distribution and vortex dynamics is attached particular attention. The results indicate the predicted cavitation pattern and pressure fluctuation agree fairly well with the experimental results. Moreover, the three equations method is utilized to assess the simulation accuracy by calculating DDES errors. It is indicated that the propeller cavitation region exhibits large error values, especially for the re-entrant jet and tip vortex cavitation region. That demonstrates the occurrence of cavitation has a considerable impact on the errors distribution. In addition, the vorticity transport equation is applied to illustrate the cavitation-vortex interaction. From the results, the vortex stretching term is dominant among the terms, and the effect of the vortex dilation term is to transport vorticity from the sheet cavitation region to the tip vortex cavitation region. Finally, the hull wake influence on cavitation is also involved in the paper. It is noted that high wake region has a great contribution to the generation and development of cavitation.

Effects of cavitation jet peening treatment on the residual stress and fatigue properties of SAF2205 cruciform welded joints

AbstractThe cruciform welded joint is a weak position of filter press to cause fatigue failure under cyclic conditions. In this study, cavitation jet peening (CJP) treatment is proposed to improve the fatigue life of SAF2205 cruciform welded joints. The effects of different CJP treatment positions on the residual stress, microstructure, and microhardness were studied. The results show that different CJP treatment positions have different on residual stresses and fatigue life. The order of the residual stress in fracture position from large to small is the fully treated specimen, untreated specimen, one‐sided treated specimen, and diagonal treated specimen, which is exactly opposite to the order of fatigue life from large to small. After the diagonal CJP treatment, the fatigue life is increased by up to 242.19%, and the residual stress at the weld toe is reduced by more than 80%. A strengthening layer with thicknesses of about 400 μm is formed.

Erosion experiments of shale using a cavitation jet

Cavitation jet has been successfully utilized in onshore and offshore petroleum engineering. In this work, the feasibility of using a cavitation jet to drill and stimulate a shale gas reservoir is investigated. Erosion experiments of shale are conducted under various hydraulic conditions. It is found that the optimal standoff distance linearly increases with upstream pressure. As the upstream pressure increases from 40 MPa to 80 MPa, the maximum erosion rate rises from 0.80 mg/min to 2.22 mg/min. An incubation stage is not observed because of the poor ductility and malleability of shale. Under an upstream pressure of 60 MPa, the maximum cumulative erosion rate at unit jet power achieves the highest value of 1.40×10−3 mg·min−1·W−1. For shale drilling, a higher pump pressure is always in favor of a greater erosion rate, but the nozzle location needs to be adjusted to meet with the optimal standoff distance. For reservoir stimulation, an erosion time of 20 min is recommended. The promoted permeability is mainly attributed to the micro pores and fractures. Besides, the erosion mechanism is discussed concerning the periodic behavior and shedding frequency of cavitation cloud, as well as the development process of erosion pit on shale.

Comparison of strengthening effect and fatigue properties of SAF2205 cruciform welded joints by ultrasonic impact and cavitation jet peening treatment

The filter press composed of SAF2205 cruciform welded joints generally works under cyclic conditions, resulting in the weld becoming a weak area of fatigue failure. In this study, the strengthening effect of cavitation jet peening treatment (CJP) and ultrasonic impact treatment (UIT) on fatigue properties of SAF2205 cruciform welded joints were compared by experiment. The effects of the three treatment methods, including UIT for the entire weld zone (UIT-A) and UIT only for the weld toe zone (UIT-T), and CJP for the entire weld zone, on residual stresses, surface roughness, microhardness, microstructure and fatigue fracture behavior were analyzed. The results indicate that the fatigue fracture initiation position of the fatigue specimens changed from the weld toe of the treated side to that of the untreated side after UIT-A, UIT-T and CJP. The fatigue life of the cruciform welded joint was increased by a maximum of 163.30% after CJP, while the UIT-A reduced the fatigue life. The order of residual stresses at the fatigue fracture initiation position from large to small was UIT-A, untreated, UIT-T and CJP specimens. Furthermore, the thickness of the formed surface strengthening layer with increased microhardness by UIT-A and CJP was 700 μm and 400 μm, respectively. The CJP could reduce the surface roughness, while the UIT had the opposite effect. The refined grains, higher dislocation density and deformation were generated on the surface after CJP and UIT. The effect of residual stress on fatigue life was more obvious than that of microstructure and surface roughness. Compared with UIT, CJP is a more effective treatment for improving the fatigue life of SAF2205 cruciform welded joints.

Experimental investigation on the ultrasonic impregnation of wood through measurements of the intensity of sonoluminescence

Ultrasonic impregnation is thought to be an effective way of permeation of liquid into material through the material-surface reforming with the attack by an ultrasonic cavitation jet or by the shock wave emitted from a collapsing bubble, or through dynamic transformation of material like a sponge. The action of a cavitation bubble can also provide penetration of liquid into the interior of the material. This paper investigates whether there is a correlation between the intensity of sonoluminescence (SL) measured at different positions and the increment in the mass of the wood material (cedar) after sonication with immersion into water in order to clarify the role of cavitation bubbles for ultrasonic impregnation. It was found that a high mass change was obtained for the material located at the position for high (the maximum) SL intensity. The number density of ultrasonic cavitation bubbles that are able to collapse leading to the emission of SL is correlated with the degree of ultrasonic impregnation.

Experimental study on ship fouling cleaning by ultrasonic-enhanced submerged cavitation jet: A preliminary study

Ship fouling is one of the essential factors that affect the economic benefits of the operational ships and the marine ecological environment. This will produce adverse effects such as increased energy consumption, increased carbon emissions, biological invasion, and hull damage. In this paper, a novel ultrasonic-enhanced submerged cavitation jet ship fouling cleaning method is proposed. The objective of this paper is to verify the feasibility of this method. A submerged cavitation jet experimental set-up was built. A mass loss method was used to evaluate the experimental results. The experimental results showed that the mass loss of samples increases greatly when the submerged cavitation jet combined with ultrasonic. This is preliminarily proved that the method of ultrasonic-enhanced submerged cavitation jet for cleaning the ship fouling is feasible. Under the pump pressures of 10 MPa and 20 MPa, the maximum mass loss of the samples were increased by 12.9% and 9.5%, respectively.

A critical comparative review of cavitation peening and other surface peening methods

Mechanical surface modification such as shot peening offer powerful enhancement of fatigue properties of metals and other materials. Cavitation usually causes surface damage in hydraulic machineries. However, careful selection of process parameters allowed developing an approach known as “cavitation peening.” Its advantage is surface roughness increase is lower than in conventional shot peening as there are no solid collisions involved. As cavitation is a hydrodynamic phenomenon, an understanding of both fluid dynamics and materials science is required. Cavitation peening is distinguished from “water jet peening,” in which water column impulse is used. Another flavor is “Submerged laser peening” that involves the use of a pulsed laser and can be considered a type of cavitation peening where cavitating bubbles are generated due to laser ablation. Ultrasound vibration, a popular method for generating cavitation for cleaning, has also been adapted for cavitation peening. The present comparative review presents key insights and achievements and addresses future directions that are required for advancing cavitation peening technology by considering the mechanisms of cavitation peening based on the reported data for water jet, pulsed laser, and ultrasonic cavitation peening. The data and methods are critically considered and summarized in comparison with shot peening. Strategic view of future challenges is presented. • Fatigue resistance enhancement using water jet, pulsed laser and ultrasonic cavitation peening was quantified • Cavitation peening using jet, pulsed laser & ultrasonic enhanced fatigue properties • Cavitation peening clearly distinguished from water jet peening • Cavitation peening benefits shown to exceed those by shot peening • Dislocation density induced by cavitation peening was lower than by shot peening • Importance of vortex cavitation is shown for experimental and numerical future work

Investigation into the Influence of Jet Cavitation Impact on Changes in Characteristics of the Surface of Structural Steel 30L and 20GL

Investigation into the Influence of Jet Cavitation Impact on Changes in Characteristics of the Surface of Structural Steel 30L and 20GL

Experimental Study on Surface Erosion of Grade A Marine Steel by Ultrahigh-Pressure Water Jet

To investigate the interaction and erosion mechanisms between an ultrahigh-pressure water jet and the surface of Grade A marine steel, this study used the ANSYS FLUENT software to simulate the hydrodynamic characteristics of an ultrahigh-pressure water jet. To erode the Grade A marine steel, a water jet with ultrahigh-pressure (200 MPa, 40 L/min) was used. An ASMC2-4 resistance strain gauge collected the dynamic strain signal at the back of the sample during jet impingement, and the simulation results were compared to experimental results. A scanning electron microscope (SEM), X-ray diffractometer (XRD), energy dispersive spectrometer (EDS), and other equipment were used to observe and analyze the phase before impact and the material surface morphology and element distribution after impact. The results reveal that as the wall shear stress increased with the target distance, the energy loss of the jet could be reduced by changing the jet incidence angle, and the peak value of the wall shear stress increased. Under the pressure of 200 MPa, the average microstrain at the back side of the impact center area of the Grade A marine steel was 180 × 10−6, and the microstrain amplitude was 35 × 10−6–50 × 10−6. The impact force of the water jet on the Grade A marine steel produced alternating stress with cyclic fluctuation. The experimental results are consistent with the simulation results. Under the alternating jet stress action, fatigue failure and cavitation failure occurred on the sample surface, which was characterized by a spalling pit, layer erosion, and cavitation hole morphology. The surface stripping model of the Grade A marine steel under an ultrahigh-pressure water jet was established, and the interaction mechanism and erosion mechanism between the ultrahigh-pressure water jet and the surface of the Grade A marine steel were elucidated.

Effect of cavitation jet on the structural, emulsifying properties and rheological properties of soybean protein‐oxidised aggregates

SummaryThe objective of this study was to investigate the effects of cavitation jets on the structural, emulsifying and rheological properties of soybean protein oxidation aggregates. The results showed that oxidation might induce the formation of larger particle sizes and molecular weight protein aggregates and the decrease of emulsifying properties. The cavitation jet at a short treatment time (<6 min) broke down the disulphide bonds and protein skeleton structures, which reduced the aggregate sizes and molecular weights and increased the emulsion activities, emulsion stabilities, apparent viscosity and elastic modulus. The cavitation jet at a long treatment time (>6 min) supported disulphide bond formation among molecules by intermolecular interactions to form protein aggregates. In addition, the skeleton structure showed cross‐linking aggregation. This increased the particle sizes and molecular weights and reduced the emulsion properties, consistency index K and elastic modulus. The findings showed that a cavitation jet at 6 min on oxidised aggregates of soybean protein might enhance the structural, emulsifying and rheological characteristics for the industry.

Development of processing technology using extremely high concentration cavitation energy by strong magnetic field

This work demonstrates a new processing technology termed magnetic energy intensive multifunction cavitation (MEI-MFC). In this technique, a strong magnetic field is used to concentrate the bubble energy while ultrasonic waves are applied from the perimeter of a water-jet cavitation jet. The cavitation bubbles are expanded while generating a swirling flow that increases the temperature and pressure of the bubbles. In addition, the presence of a strong magnetic field at the nozzle outlet and the collisions of charged bubbles induced by the Lorentz force cause a significant increase in the number of bubbles and the energy density. This enhanced cavitation processing technology can be applied to various materials to improve strength and to induce functionalization. The peening of austenitic stainless steel using this technique provides a highly corrosion-resistant surface while suppressing the formation of martensite and preventing sensitization by generating a new surface microstructure with a toughened layer directly underneath.

Improvement of electromagnetic interference properties of 3D few-layer graphene composite by means of freeze-drying

In this paper, we present a facile, green, and scalable approach for preparing high-quality few-layer graphene (FLG) nanoplatelets through a jet cavitation process. The electromagnetic interference (EMI) performance of FLG of three different lateral sizes is investigated. The midsized FLG (M-FLG) exhibits the best EMI performance. The jet-exfoliation technology used herein preserves the structure of FLG with few structural defects. The ID/IG ratio of M-FLG is as low as 0.092. Furthermore, we introduce 20 wt% M-FLG into paraffin wax to obtain a bulk material for conducting shielding measurements. The shielding effectiveness (SE) in the X-band is 19.28 dB, which exceeds that of unexfoliated graphite. Finally, we use freeze-drying technology to inhibit stacking of the graphene suspension during drying. The SE of the freeze-dried M-FLG (M-FLG-fd) increased considerably to 39 dB. The results indicate that jet cavitation combined with freeze-drying substantially improved the dielectric properties and absorption capabilities of FLG.

Numerical Simulation and Experimental Research of Cavitation Jets in Dual-Chamber Self-Excited Oscillating Pulsed Nozzles

Self-excited oscillating pulsed cavitation jet has many advantages, such as easy operation, simply maintenance, and low investment costs. Based on the structural parameters of the traditional Helmholtz and organ pipe single-chamber self-excited oscillating pulsed nozzles, Helmholtz + Helmholtz, organ pipe + organ pipe, and Helmholtz + organ pipe dual-chamber self-excited oscillating pulsed nozzles with different structures are established in series, and the internal flow field of the dual chamber is studied to obtain the best combination nozzle by comparing numerical simulation and erosion experiments. The results indicate that the cleaning effect is the best when adopting the combined structure of Helmholtz + organ pipe, which brings out the largest volume fraction of the nozzle cavity with higher gas content and higher kinetic energy with larger jet velocity. By comparing the erosion experiments, it is found that the flushing area and erosion depth of the nozzle with the ratio of cavity and wall (D/a) of 2.50 is significantly higher than the nozzle with the ratio of cavity and wall (D/a) of 5.00. The pulse pressure of the flushing target increases by 0.0044 MPa, the pressure amplitude of the former changes significantly in the same cavitation cycle, and the cleaning effect is best.

Preparation of graphene by supercritical CO2 circulating exfoliation with a jet cavitation

In this paper, a low-cost graphene exfoliation method suitable for large-scale production was explored. The pure scCO2 was used as the exfoliation agent. In addition, a flow channel structure was designed to perform field strengthening induced cavitation, and high pressure and cavitation field were combined to directly prepare graphene. In the optimization of operating conditions, the effects of circular time, reaction pressure, circular flow rate and centrifugal speed on the exfoliation were studied. The graphene product has a maximum dispersion concentration of 0.701 mg·mL−1 and the intensity ratio ID/IG of 0.181, which guaranteed the yield while taking into account the graphene quality. The proportion of graphene with less than five layers was 68%, 75% of the lateral dimensions were in the range of (1−4) μm. Finally, the existence of cavitation field was verified by numerical simulation to provide a basis for further optimization.

Research on the Law of Head Loss of Jet Pumps in the Cavitation State

Liquid flow is subject to head loss because of viscous force, surface tension, friction force, and so on. Part of the energy is irreversibly converted into heat, which then dissipates into the environment. Head loss intensifies in the turbulent state. At present, few studies explore the law of head loss caused by secondary flow, cavitation intensity, and turbulence intensity. In this study, the head losses in different sections of a jet pump were studied by controlling the cavitation number σ, the secondary flow rate Qs, and the inlet pressure pi. The experimental results were analyzed with the aid of computational fluid dynamics. The results show that an increase in Qs can weaken the variations of Qs and suction pressure ps in the transitional stage of cavitation. Besides, σ, Qs, and pi influence head loss to varying extents. Cavitation intensity and turbulence intensity are the main factors for head loss and jet temperature difference. In particular, the influence of Qs on head loss provides guidance both for reducing the energy loss of the quantitative adding device and jet aerator and for expanding the stable adding range of the jet. More importantly, the main factors of energy loss caused by jet cavitation were analyzed in detail, which can effectively facilitate the pipeline design to reduce the local and frictional head loss.

Improving the corrosion and stress corrosion cracking resistance of 316 L stainless steel in high temperature water by water jet cavitation peening

Water jet cavitation peening (WJP) was used to improve the corrosion and stress corrosion cracking (SCC) of cold worked 316L stainless steel (316L SS) in high temperature water. WJP induced changes in residual stress and microstructure of the surface layer on corrosion and SCC were investigated. The investigation was conducted by comparing the corrosion and SCC of the un-treated (UT) and WJP treated specimens by exposure tests and slow strain rate tensile (SSRT) tests. The results revealed that WJP obviously improved the corrosion and SCC resistance of 316L SS, which is attributed to the increase of residual compressive stress and the change of the microstructure of the surface layer.

Aggressive ability improvement of self-resonating cavitating jets with double-hole nozzle

The aggressive ability of cavitating jets generated by a double-hole nozzle was investigated under an ambient pressure condition to improve the erosion efficiency for potential applications such as underground drilling. The erosion damage was experimentally investigated for a series of pitch–hole ratios to understand the erosion mechanism of the double-hole cavitating jets. The flow characteristics of various erosion patterns were numerically investigated using two-phase computational fluid dynamics (CFD) calculations. The stages of erosion suppression in the pitch–hole ratio range wp∈ [1.25, 3] and erosion enhancement in wp∈ [3.5, 6] were observed based on the mass loss Δm across the entire range of standoff distance ratio ls. Two erosion patterns were identified according to the erosion features, designated as A and B, with increasing standoff distance ratio ls. Erosion occurs in multiple scattered regions in pattern A and which appears as two symmetric D-shaped regions in pattern B. In contrast to the single-hole jet, the aggressive ability was significantly improved a wp = 4.5 with higher Δm peaks. Double-hole cavitating jets at the optimum pitch–hole ratio achieve the highest streamwise velocity and the weakest interaction between the two jets. The cavitation clouds in the impinging jets generated by the optimum pitch–hole nozzle primarily collapse in the D-shaped main erosion region, which enhances the erosion damage of the double-hole cavitating jets at the optimum standoff distance ratios.

Numerical prediction of erosion due to a cavitating jet

We numerically investigate the erosion potential of a cavitating liquid jet by means of high-resolution finite volume simulations. As thermodynamic model, we employ a barotropic equilibrium cavitation approach, embedded into a homogeneous mixture model. To resolve the effects of collapsing vapor structures and to estimate the erosion potential, full compressibility is considered. Two different operating points featuring different cavitation intensities are investigated and their erosion potential is estimated and compared. Different methods are used for this purpose, including collapse detection (Mihatsch et al., 2015), maximum pressure distribution on the wall, and a new method of generating numerical pit equivalents. The data of numerical pit equivalents is analyzed in detail and compared with experimental data from the literature. Furthermore, a comprehensive grid study for both operating points is presented.

Numerical investigation of ozone decomposition by self-excited oscillation cavitation jet

Abstract Extreme environmental changes caused by the cavitation bubble collapse, such as high pressure, high temperature and the microjet, will cause pyrolysis reaction at the gas and liquid interface inside the bubble. Self-excited pulsed cavitation jet has an instantaneous strong pulse pressure, which leads to local hot spots surrounding the cavitation bubbles. The generation of strong oxidizing free radicals promotes easy ozone conversion into oxygen. Numerical simulations were conducted for ozone decomposition by cavitation jet. Three groups of different collision angles were applied to compare and analyze the ozone degradation reaction. Results showed that the collision angle has a certain influence on the chemical reaction intensity, the degradation of ozone, and oxygen production. At the collision angle of 180°, the chemical reaction was the most violent, with ozone degradation and oxygen production at the highest level, followed by 120° and lowest at 90°.