During high-speed operation,mixed-flow pumps are susceptible to cavitation,which destabilizes the internal flow,increases energy losses,and degrades hydraulic efficiency.To assess the effectiveness of blade perforatio...During high-speed operation,mixed-flow pumps are susceptible to cavitation,which destabilizes the internal flow,increases energy losses,and degrades hydraulic efficiency.To assess the effectiveness of blade perforation as a cavitation-mitigation strategy,in this study several mixed-flow pump models incorporating perforations were developed.Numerical simulations were performed for configurations with circular holes positioned at different locations along the blade leading edge,and the computational results were validated against experimental measurements.The findings indicate that the location of the perforations plays a decisive role in cavitation suppression.Moving from the blade rim toward the hub along the leading edge,the critical net positive suction head,NPSH_(cr),initially decreases and subsequently increases,while remaining consistently lower than that of the reference non-perforated configuration.The perforations promote the transfer of high-pressure fluid from the pressure side to the suction side of the blade,thereby alleviating local low-pressure regions.This pressure compensation significantly reduces the extent of low-pressure zones in the vicinity of the perforations,leading to a marked suppression of cavitation both locally and downstream of the perforated regions.展开更多
Hydrodynamic cavitation,as an efficient technique applied in many physical and chemical treatment methods,has been widely used by various industries and in several technological fields.Relevant generators,designed wit...Hydrodynamic cavitation,as an efficient technique applied in many physical and chemical treatment methods,has been widely used by various industries and in several technological fields.Relevant generators,designed with specific structures and parameters,can produce cavitation effects,thereby enabling effective treatment and reasonable transformation of substances.This paper reviews the design principles,performance,and practical applications associated with different types of cavitation generators,aiming to provide theoretical support for the optimization of these systems.It systematically analyzes the underpinning mechanisms and the various factors influencing the cavitation phenomena,also conducting a comparative analysis of the performance of different types of generators.Specific applications dealing with wastewater treatment,chemical reaction acceleration,and other fields are discussed together with the advantages,disadvantages,and applicability of each type of cavitation generator.We also explore research progress in areas such as cavitation stability,energy efficiency,and equipment design upgrades.The study concludes by forecasting the application prospects of intelligent design and computational fluid dynamics(CFD)in optimizing and advancing cavitation generators.It proposes new ideas for the further development of cavitation technology and highlights directions for its widespread future application.展开更多
Cavitation is an unavoidable phenomenon in the operation of centrifugal pumps.Prolonged cavitation can cause significant damage to the components of the flow channel,and in severe cases,it may even interfere with the ...Cavitation is an unavoidable phenomenon in the operation of centrifugal pumps.Prolonged cavitation can cause significant damage to the components of the flow channel,and in severe cases,it may even interfere with the normal energy exchange processes within the pump.Therefore,effective monitoring of cavitation in centrifugal pumps is crucial.This article presents a study that approaches the issue from an acoustic perspective,using experimental methods to gather and analyze acoustic data at the inlet and outlet of centrifugal pumps across various flow rates,with hydrophones as the primary measuring instruments.Results show that flow rate significantly affects noise levels in both non-cavitation and mild cavitation stages,with noise increasing as the flow rate rises.As the cavitation margin(NPSHa)decreases,inlet and outlet noise trends diverge:inlet noise drops sharply,while outlet noise initially increases before sharply decreasing.Both exhibit a distinct zone of abrupt change,where NPSHa values offer earlier cavitation detection than traditional methods.The noise at the pump’s inlet and outlet primarily consists of discrete and broadband noise,with most energy concentrated at discrete frequencies—shaft frequency(24 Hz),blade frequency(144 Hz),and their harmonics.As NPSHa decreases,the inlet’s discrete and broadband noise frequencies decline,while they increase at the outlet.Monitoring changes in these spectrum characteristics provides an additional means of predicting cavitation onset.展开更多
Hydrodynamic cavitation is considered to be a promising technology for process intensification,due to its high energy efficiency,cost-effective operation,ability to induce chemical reactions,and scale-up possibilities...Hydrodynamic cavitation is considered to be a promising technology for process intensification,due to its high energy efficiency,cost-effective operation,ability to induce chemical reactions,and scale-up possibilities.In the past decade,advancements have been made in the fundamental understanding of hydrodynamic cavitation and its main variables,which provide a basis for applications of hydrodynamic cavitation in radical-induced chemical reaction processes.Here,we provide an extensive review of these research efforts,including the fundamentals of hydrodynamic cavitation,the design of cavitation reactors,cavitation-induced reaction enhancement,and relevant industrial applications.Two types of hydrodynamic cavitation reactors—namely,stationary and rotational—are compared.The design parameters of a hydrodynamic cavitation reactor and reactor performance at the laboratory and pilot scales are discussed,and recommendations are made regarding optimal operation and geometric conditions.The commercial cavitation reactors that are currently on the market are reviewed here for the first time.The unique features of hydrodynamic cavitation have been widely applied to various chemical reactions,such as oxidization reactions and wastewater treatment,and to physical processes,such as emulsion generation and component extraction.The roles of radicals and gas bubble implosion are also thoroughly discussed.展开更多
Bubbles play crucial roles in various fields,including naval and ocean engineering,chemical engineering,and biochemical engineering.Numerous theoretical analyses,numerical simulations,and experimental studies have bee...Bubbles play crucial roles in various fields,including naval and ocean engineering,chemical engineering,and biochemical engineering.Numerous theoretical analyses,numerical simulations,and experimental studies have been conducted to reveal the mysteries of bubble motion and its mechanisms.These efforts have significantly advanced research in bubble dynamics,where theoretical study is an efficient method for bubble motion prediction.Since Lord Rayleigh introduced the theoretical model of single-bubble motion in incompressible fluid in 1917,theoretical studies have been pivotal in understanding bubble dynamics.This study provides a comprehensive review of the development and applicability of theoretical studies in bubble dynamics using typical theoretical bubble models across different periods as a focal point and an overview of bubble theory applications in underwater explosion,marine cavitation,and seismic exploration.This study aims to serve as a reference and catalyst for further advancements in theoretical analysis and practical applications of bubble theory across marine fields.展开更多
The synergetic technology of hydrodynamic cavitation(HC)and peroxydisulfate(PDS)has been adopted for the treatment of organic pollutants,while the rationale behind the thermal-activation of PDS in this process remains...The synergetic technology of hydrodynamic cavitation(HC)and peroxydisulfate(PDS)has been adopted for the treatment of organic pollutants,while the rationale behind the thermal-activation of PDS in this process remains lacking.This paper presented investigation on the degradation of tetracycline under two types of operating conditions,including“internal reaction conditions”(pH value and TC/PDS molar ratio)and“external physical conditions”(hole shape,solution temperature and inlet pressure).Special emphasis was paid on the analysis of thermal effects through a robust modeling approach.The results showed that a synergy index of 6.26 and a degradation rate of 56.71%could be obtained by the HC-PDS process,respectively,when the reaction conditions were optimized.Quenching experiment revealed that·OH and·SO_(4)^(-)were the predominant free radicals and their contribution to the degradation was 75.4%and 24.6%respectively,since a part of·SO_(4)^(-)was transformed into·OH in the solution.The thermal activation of PDS mainly occurred near the hole where the fitting temperature was around 340 K,while·OH was generated in the bubble collapse region downstream the hole,where the temperature was much higher and favorable for the cleavage of water molecular.The average temperature under different external physical conditions was in good consistence with the degradation rates.This research developed a useful method to effectively evaluate the activation extent of PDS by HC and could provide reliable guidance for further development of cavitational reactors to treat organic pollutants based on this hybrid approach.展开更多
In this paper,the load characteristics of shock wave,bubble pulsating water jet and cavitation closure are studied by carrying out underwater explosion experiments and numerical simulation of fixed square plates with ...In this paper,the load characteristics of shock wave,bubble pulsating water jet and cavitation closure are studied by carrying out underwater explosion experiments and numerical simulation of fixed square plates with 2.5,5 and 10 g trinitrotoluene.The results show that under the combined action of multiple loads,the impulse of bubble pulsation and water jet load plays a leading role in the process of underwater explosion,and the impulse of cavitation closure load is greater than that of shock wave.The damage to the structure cannot be ignored,and the pressure time-history curve presents a“multi-peak”state,and it is pointed out that the water jet is a concentrated load.Then,the dynamic response of the full-scale model of the ship under the combined action of multiple loads is studied,and the dynamic response of the ship under different cabin water depths and different explosion distances is discussed.The results show that when the ship is empty,the damage degree of the ship is the most serious,and the influence of cavitation effect on the half cabin is weaker than that of the empty cabin,so the damage degree is the second,and the damage degree is the smallest when the cabin is full.When the distance parameter is less than 0.68,the shock wave and the after flow play a leading role in the dynamic response of the ship.When the distance parameter is between 0.68 and 1.38,the combined action of the bubble pulsating water jet and the cavitation closure multi-load causes the main damage to the ship.When the distance parameter is greater than 1.38,the bubble pulsation and the cavitation closure load play a leading role.展开更多
A floating horizontal-axis tidal current turbine(HATT)is an underwater power generation device where cavitation inevitably occurs on blade surfaces,severely affecting a turbine’s lifespan.Under wave action,these floa...A floating horizontal-axis tidal current turbine(HATT)is an underwater power generation device where cavitation inevitably occurs on blade surfaces,severely affecting a turbine’s lifespan.Under wave action,these floating turbines exhibit six degrees of freedom motion,potentially intensifying the cavitation on the blade surfaces.This study selects three types of oscillatory motions from the six degrees of freedom:roll,yaw,and pitch.Computational fluid dynamics(CFD)methods are used for numerical calculations,and transient simulations of multiphase flow are conducted on the basis of the Reynolds-Averaged Navier-Stokes(RANS)model.Research has revealed strong correlations between flow velocity,the blade tip speed ratio,and cavitation.During oscillatory motion,the motion period and amplitude also significantly impact cavitation.In roll motion,the cavitation rate can increase by up to 59%with decreasing period,whereas in pitch and yaw motions,the increases are 7.57 times and 36%larger,respectively.With an increase in amplitude during roll motion,the cavitation rate can increase by up to 1.08 times,whereas in pitch and yaw motions,the increases are 3.49 times and 45%,respectively.The cavitation rate on the blade surfaces is the highest in pitch motion,followed by roll and yaw motions.展开更多
Bulb-type hydro turbines are commonly used in small-to medium-scale hydropower stations due to their compact design and adaptability to low-head conditions.However,long-termoperation often results in wear at the runne...Bulb-type hydro turbines are commonly used in small-to medium-scale hydropower stations due to their compact design and adaptability to low-head conditions.However,long-termoperation often results in wear at the runner rim,increasing tip clearance and triggering leakage flow and cavitation.These effects reduce hydraulic efficiency and accelerate blade surface erosion,posing serious risks to unit safety and operational stability.This study investigates the influence of tip clearance on cavitation performance in a 24 MW prototype bulb turbine.A three-dimensional numericalmodel is developed to simulate various operating conditions with different tip clearance values(3.0,4.5,and 6.0 mm)and cavitation numbers(σ=1.20–1.33).Internal flow characteristics—including pressure distribution,velocity fields,hydraulic efficiency,and pressure pulsation—are analyzed to elucidate the impact of tip clearance on cavitation development.Results show that underσ=1.2 and a 4.5 mm tip clearance,the pressure pulsation amplitude at the blade tip reaches 4870 Pa—approximately 1.5 times higher than that near the hub.At partial flowconditions,turbine efficiency decreases by up to 6.8%compared to the rated condition.Increasing the tip clearance from 1.5 to 6.0 mm expands the low-pressure area near the blade tip by around 32%,significantly intensifying cavitation.Frequency domain analysis reveals dominant pulsation frequencies between 10–20Hz,characterized by blade-passing features and a wave-clipping effect.These findings provide theoretical insight and quantitative evidence to support the optimization of tip clearance design and cavitation mitigation strategies in bulb turbines,aiming to improve both efficiency and operational stability.展开更多
The corrosion and cavitation erosion(CE)behavior of Co-6Ti-11V-9Cr alloy are investigated in both deionized water and 3.5 wt.%NaCl solution.Utilizing electrochemical methods and CE testing,the research aims to clarify...The corrosion and cavitation erosion(CE)behavior of Co-6Ti-11V-9Cr alloy are investigated in both deionized water and 3.5 wt.%NaCl solution.Utilizing electrochemical methods and CE testing,the research aims to clarify the synergistic effects of CE and corrosion.The results demonstrate that after 8 h of CE exposure,Co-6Ti-11V-9Cr alloy experienced a cumulative mass loss of 1.84 mg in deionized water and 3.42 mg in NaCl solution,leading to mass loss rates of 0.23 and 0.43 mg/h,respectively.In NaCl solution,CE was responsible for 53.8%of the overall damage,with the remaining damage attributed to the combined influences of corrosion and CE.Under CE conditions,both the corrosion potential and corrosion current density of the alloy increased,which accelerated the corrosion process and exacerbated cavitation damage.The material sustained more severe damage in 3.5 wt.%NaCl solution over the same cavitation durations.Ultimately,CE damage mechanism of Co-6Ti-11V-9Cr superalloy was elucidated based on relevant experimental observations.展开更多
With the acceleration of industrialization and urbanization,ammonia nitrogen pollution in water bodies has become increasingly severe,making the development of efficient and low-consumption wastewater treatment tech-n...With the acceleration of industrialization and urbanization,ammonia nitrogen pollution in water bodies has become increasingly severe,making the development of efficient and low-consumption wastewater treatment tech-nologies highly significant.This study employs three-dimensional computational fluid dynamics(CFD)to investigate the cavitation mechanisms and flow field characteristics in a novel jet impingement-negative pressure ammonia removal reactor.The simulation,validated by experimental pressure data with a high degree of consistency,utilizes the Mixture model,the Realizable k-εturbulence model,and the Schnerr-Sauer cavitation model.The results demonstrate that the flow velocity undergoes a substantial acceleration within the orifice nozzle,triggering a dramatic pressure drop from an inlet value of approximately 1.17 MPa to below the saturated vapor pressure,reaching as low as−109 kPa,which induces intense cavitation.Cavitation bubbles primarily originate on the inner wall of the nozzle,with the vapor volume fraction peaking at about 0.42 within the orifice.A strong positive correlation was observed between the local vapor fraction and the flow velocity,indicating that cavitation enhances jet intensity.Furthermore,vortex structures near the wall and within the jacket sustain low-pressure zones,facilitating continuous cavitation and efficient mixing.This study quantitatively elucidates the cavitation dynamics and its interplay with the flow field,providing a solid theoretical and numerical basis for optimizing the reactor design to enhance ammonia removal efficiency.展开更多
Polymer microfluidic chips are a common tool in biomedical research,and the production of mold inserts with microscale structures represents a crucial step in the precise molding of these chips.Electrical discharge ma...Polymer microfluidic chips are a common tool in biomedical research,and the production of mold inserts with microscale structures represents a crucial step in the precise molding of these chips.Electrical discharge machining(EDM)can achieve high-quality machining of microstructures on high-hardness mold steel inserts.This can reduce the manufacturing cost of microfluidic chip molds and extend the service life of molds.However,the EDM process is susceptible to the formation of poor-quality surfaces due to the occurrence of abnormal discharges.To address this issue,this paper presents in-depth research on a novel ultrasonic cavitation-assisted electrical discharge machining method.An ultrasonic transducer is placed in an electrical discharge working fluid to promote the removal of electrical corrosion products through the cavitation effect of the liquid.This can also reduce the occurrence of poor discharge,thereby improving the machining surface quality.The aluminum foil corrosion method is employed to investigate the distribution of ultrasonic action in the electric discharge working fluid.The attenuation law of ultrasonic action in the electric discharge working fluid is also investigated.The range of ultrasonic action is determined,providing a reference for subsequent ultrasonic vibration electric discharge working fluid processing experiments.The results of the aluminum foil tests are used to inform the selection of NAK80 mold steel as the experimental object.The effects of cavitation at three ultrasonic frequencies on the surface microstructure are investigated.The experimental results indicate that ultrasonic cavitation can facilitate the movement of corrosion products in electrical machining,reduce the occurrence of abnormal discharges caused by carbon deposition or the secondary re-melting of metals,and thereby enhance the machining surface quality.展开更多
This study presents a numerical analysis of the effects of a rigid flat wall with oscillating motion on the pressure wave propagation during a single spherical cavitation bubble collapse at different initial bubble po...This study presents a numerical analysis of the effects of a rigid flat wall with oscillating motion on the pressure wave propagation during a single spherical cavitation bubble collapse at different initial bubble positions.Different nondimensional distances S=0.8,0.9,1.0,1.1,1.2 and 1.3 were considered to investigate the effects of initial in-phase and out-of-phase oscillations of the flat wall.Numerical simulations of cavitation bubble collapse near an oscillating wall were conducted using a compressible two-phase flow model.This model incorporated the Volume of Fluid(VOF)interface-sharpening technique on a general curvilinear moving grid.The numerical results were consistent with published experimental data.The simulation examined the impact of oscillating walls on bubble behavior and the resulting pressure peaks observed on the wall surface.The numerical results demonstrate the significant impact of wall oscillation conditions on bubble collapse and migration behavior,and consequently,the generation of pressure waves with significantly different propagation and pressure peaks induced by shock impact on the rigid wall.Different behaviors were observed in the trendlines of the pressure peaks and maximum jet velocity under in-phase and out-of-phase oscillating walls,with distinct values.At S≥1.0,a higher-pressure peak on the wall was observed in the case of the out-of-phase oscillating condition,whereas a higher-pressure peak was found in the case of the in-phase condition at S<1.0.The highest-pressure peak was found at S=0.8 in trend lines of in-phase and S=1.1 in trend lines of out-of-phase oscillation effects.展开更多
In order to enhance the ultrasonic degradation rate of organic solutions,a metal plate is placed at the water–air interface of the ultrasonic cleaning tank.Initially,the distribution of the acoustic field in the ultr...In order to enhance the ultrasonic degradation rate of organic solutions,a metal plate is placed at the water–air interface of the ultrasonic cleaning tank.Initially,the distribution of the acoustic field in the ultrasonic water tank was calculated using the simulation software COMSOL.The simulation results demonstrated that the utilization of the metal plate can eliminate the standing-wave acoustic field to a certain extent.Subsequently,the pixel method was selected for a quantitative comparison of the cavitation area in the flume with and without the metal plate.The results demonstrated that,under specific conditions,the area of ultrasonic cavitation in the water tank can be expanded using a metal plate.Thereafter,an acoustic degradation experiment was designed to confirm the feasibility of the simulation method.Furthermore,the impacts of the amplitude of the incident ultrasonic pressure,frequency,and the height of the liquid level in the water tank on the cavitation area were investigated.展开更多
Selective laser melting(SLM),a laser-powder bed fusion(L-PBF)additive manufacturing technique,demonstrates significant potential for enhancing the mechanical performance of Al-Si alloys.In this study,three representat...Selective laser melting(SLM),a laser-powder bed fusion(L-PBF)additive manufacturing technique,demonstrates significant potential for enhancing the mechanical performance of Al-Si alloys.In this study,three representative hypoeutectic Al-Si alloys(AlSi7Mg,AlSi10Mg,and AlSi12)were fabricated via SLM additive manufacturing to systematically investigate the influence of silicon content on microstructural evolution and mechanical properties.Advanced characterization techniques including scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),and transmission electron microscopy(TEM)were employed to systematically examine the cavitation erosion behavior of additive-manufactured Al-Si(AM Al-Si)alloys.The experimental findings reveal that varying silicon content predominantly alters the morphology and dimensions of the silicon network structure in AM Al-Si alloys,particularly through modulation of cellular silicon wall thickness.This microstructural modification was identified as the primary determinant in enhancing cavitation erosion(CE)resistance,with the refined silicon network architecture effectively impeding crack propagation and phase boundary delamination under CE conditions.展开更多
In order to reveal the cavitation erosion mechanisms of Fe_(50)Mn_(30)Co_(10)Cr_(10)coating prepared by laser melting deposition(LMD)technique,the phase composition evolution,microstructure,microhardness,cavitation er...In order to reveal the cavitation erosion mechanisms of Fe_(50)Mn_(30)Co_(10)Cr_(10)coating prepared by laser melting deposition(LMD)technique,the phase composition evolution,microstructure,microhardness,cavitation erosion resistance and failure mechanisms were investigated.The results demonstrate that the amount of martensite HCPεphase of the coating surface increased by a factor of 2.43,and the microhardness increased from HV 270 to HV 410 after 20 h of cavitation erosion test in distilled water.The cumulative volume loss of the coating was approximately 55%less than that of AlCoCrxCuFe(x=2.0),and the cumulative mean depth of erosion(MDE)was 9%that of FeCoCrAlNiTix(x=2.0).The surface strength and plasticity of the coating were further strengthened in the process of cavitation erosion due to the back stress strengthening and work hardening mechanism caused by the heterogeneous structure,which effectively improved the cavitation erosion resistance of the coating.展开更多
The cavitation incipience and development of water flow over a thin hydrofoil placed in the test section of high-speed cavitation tunnel were investigated.Hydrofoils with smooth and rough leading edge were tested for ...The cavitation incipience and development of water flow over a thin hydrofoil placed in the test section of high-speed cavitation tunnel were investigated.Hydrofoils with smooth and rough leading edge were tested for different upstream velocities and incidence angles.The observations clearly revealed that cavitation incipience is enhanced by roughness at incidence angle below 2°.This is in line with the former reports,according to whose roughness element decreases the wettability and traps a larger amount of gas.As a result,surface nucleation is enhanced with an increased risk of cavitation.Surprisingly,for higher incidence angles(>3°),it was found that cavitation incipience is significantly delayed by roughness while developed cavitation is almost the same for both smooth and rough hydrofoils.This unexpected incipience delay is related to the change in the boundary layer structure due to roughness.It was also reported a significant influence of roughness on the dynamic of developed cavitation and shedding of transient cavities.展开更多
A transient multiphase CFD （computational fluid dynamics） model was set up to investigate the main causes which lead to cavitation in PD （positive displacement） reciprocating pumps. Many authors agree on distingui...A transient multiphase CFD （computational fluid dynamics） model was set up to investigate the main causes which lead to cavitation in PD （positive displacement） reciprocating pumps. Many authors agree on distinguishing two different types of cavitation affecting PD pumps： flow induced cavitation and cavitation due to expansion. The flow induced cavitation affects the zones of high fluid velocity and consequent low static pressure e.g. the valve-seat volume gap while the cavitation due to expansion can be detected in zones where the decompression effects are important e.g. in the vicinity of the plunger. This second factor is a distinctive feature of PD pumps since other devices such as centrifugal pumps are only affected by the flow induced type. Unlike what has been published in the technical literature to date, where analysis of positive displacement pumps are based exclusively on experimental or analytic methods, the work presented in this paper is based entirely on a CFD approach, it discusses the appearance and the dynamics of these two phenomena throughout an entire pumping cycle pointing out the potential of CFD techniques in studying the causes of cavitation and assessing the consequent loss of performance in positive displacement pumps.展开更多
Cavitation generation methods have been used in multifarious directions because of their diversity,and numerous studies and discussions have been conducted on cavitation generation methods.This study aims to explore t...Cavitation generation methods have been used in multifarious directions because of their diversity,and numerous studies and discussions have been conducted on cavitation generation methods.This study aims to explore the generating mechanism and evolution law of volume alternate cavitation(VAC).In the VAC,liquid water is placed in an airtight container with a variable volume.As the volume alternately changes,the liquid water inside the container continues to cavitate.Then,the mixture turbulence model and in-cylinder dynamic grid model are adopted to conduct computational fluid dynamics simulation of volume alternate cavitation.In the simulation,the cloud images at seven heights on the central axis are monitored,and the phenomenon and mechanism of height and eccentricity are analyzed in detail.By employing the cavitation flow visualization method,the generating mechanism and evolution law of cavitation are revealed.The synergistic effects of experiments and high-speed camera capturing confirm the correctness of the simulation results.In the experiment,the volume change stroke of the airtight container is set to 20 mm,the volume change frequency is 18 Hz,and the shooting frequency of the high-speed camera is set to 10000 FPS.The experimental results indicate that the position of the cavitation phenomenon has a reasonable law during the whole evolution cycle of the cavitation cloud.Also,the volume alternation cycle corresponds to the generation,development,and collapse stages of cavitation bubbles.展开更多
Conventional,submicron and multimodal WC-12Co cermet coatings were deposited by high velocity oxy-fuel（HVOF）.The microhardness and microstructure of the coatings were compared,and the resistance of the coatings to c...Conventional,submicron and multimodal WC-12Co cermet coatings were deposited by high velocity oxy-fuel（HVOF）.The microhardness and microstructure of the coatings were compared,and the resistance of the coatings to cavitation erosion was studied by ultrasonic vibration cavitation equipment.Cavitation pits and craters were observed by SEM and cavitation mechanisms were explored.The results show that the microstructures of submicron and multimodal WC-12Co coatings prepared by HVOF are dense with little porosity,and their microhardness values are obviously higher than that of the conventional WC-12Co coating.The average microhardness of multimodal WC-12Co coating reaches nearly HV1500,which is much higher than that of the conventional one.As well,it is found that the multimodal WC-12Co coating exhibits the best cavitation erosion resistance among the three coatings,the erosion rate is approximately 40% that of the conventional coating,and the cavitation erosion resistance of multimodal WC-12Co coating is enhanced by above 150% in comparison with the conventional coating.展开更多
基金the National Key Research and Development Project of China(No.2019YFB 2005300)the Natural Science Foundation of Jiangsu Province(No.BK20220609)the National Natural Science Foundation of China(Grant Nos.52109106,52409122,and 12272187).
文摘During high-speed operation,mixed-flow pumps are susceptible to cavitation,which destabilizes the internal flow,increases energy losses,and degrades hydraulic efficiency.To assess the effectiveness of blade perforation as a cavitation-mitigation strategy,in this study several mixed-flow pump models incorporating perforations were developed.Numerical simulations were performed for configurations with circular holes positioned at different locations along the blade leading edge,and the computational results were validated against experimental measurements.The findings indicate that the location of the perforations plays a decisive role in cavitation suppression.Moving from the blade rim toward the hub along the leading edge,the critical net positive suction head,NPSH_(cr),initially decreases and subsequently increases,while remaining consistently lower than that of the reference non-perforated configuration.The perforations promote the transfer of high-pressure fluid from the pressure side to the suction side of the blade,thereby alleviating local low-pressure regions.This pressure compensation significantly reduces the extent of low-pressure zones in the vicinity of the perforations,leading to a marked suppression of cavitation both locally and downstream of the perforated regions.
文摘Hydrodynamic cavitation,as an efficient technique applied in many physical and chemical treatment methods,has been widely used by various industries and in several technological fields.Relevant generators,designed with specific structures and parameters,can produce cavitation effects,thereby enabling effective treatment and reasonable transformation of substances.This paper reviews the design principles,performance,and practical applications associated with different types of cavitation generators,aiming to provide theoretical support for the optimization of these systems.It systematically analyzes the underpinning mechanisms and the various factors influencing the cavitation phenomena,also conducting a comparative analysis of the performance of different types of generators.Specific applications dealing with wastewater treatment,chemical reaction acceleration,and other fields are discussed together with the advantages,disadvantages,and applicability of each type of cavitation generator.We also explore research progress in areas such as cavitation stability,energy efficiency,and equipment design upgrades.The study concludes by forecasting the application prospects of intelligent design and computational fluid dynamics(CFD)in optimizing and advancing cavitation generators.It proposes new ideas for the further development of cavitation technology and highlights directions for its widespread future application.
基金supported by the National Natural Science Foundation of China(Research Project No.52169018).
文摘Cavitation is an unavoidable phenomenon in the operation of centrifugal pumps.Prolonged cavitation can cause significant damage to the components of the flow channel,and in severe cases,it may even interfere with the normal energy exchange processes within the pump.Therefore,effective monitoring of cavitation in centrifugal pumps is crucial.This article presents a study that approaches the issue from an acoustic perspective,using experimental methods to gather and analyze acoustic data at the inlet and outlet of centrifugal pumps across various flow rates,with hydrophones as the primary measuring instruments.Results show that flow rate significantly affects noise levels in both non-cavitation and mild cavitation stages,with noise increasing as the flow rate rises.As the cavitation margin(NPSHa)decreases,inlet and outlet noise trends diverge:inlet noise drops sharply,while outlet noise initially increases before sharply decreasing.Both exhibit a distinct zone of abrupt change,where NPSHa values offer earlier cavitation detection than traditional methods.The noise at the pump’s inlet and outlet primarily consists of discrete and broadband noise,with most energy concentrated at discrete frequencies—shaft frequency(24 Hz),blade frequency(144 Hz),and their harmonics.As NPSHa decreases,the inlet’s discrete and broadband noise frequencies decline,while they increase at the outlet.Monitoring changes in these spectrum characteristics provides an additional means of predicting cavitation onset.
基金The authors are grateful for the financial support provided by the Natural Sciences and Engineering Research Council of Canada(RGPIN_2019-06614).
文摘Hydrodynamic cavitation is considered to be a promising technology for process intensification,due to its high energy efficiency,cost-effective operation,ability to induce chemical reactions,and scale-up possibilities.In the past decade,advancements have been made in the fundamental understanding of hydrodynamic cavitation and its main variables,which provide a basis for applications of hydrodynamic cavitation in radical-induced chemical reaction processes.Here,we provide an extensive review of these research efforts,including the fundamentals of hydrodynamic cavitation,the design of cavitation reactors,cavitation-induced reaction enhancement,and relevant industrial applications.Two types of hydrodynamic cavitation reactors—namely,stationary and rotational—are compared.The design parameters of a hydrodynamic cavitation reactor and reactor performance at the laboratory and pilot scales are discussed,and recommendations are made regarding optimal operation and geometric conditions.The commercial cavitation reactors that are currently on the market are reviewed here for the first time.The unique features of hydrodynamic cavitation have been widely applied to various chemical reactions,such as oxidization reactions and wastewater treatment,and to physical processes,such as emulsion generation and component extraction.The roles of radicals and gas bubble implosion are also thoroughly discussed.
文摘Bubbles play crucial roles in various fields,including naval and ocean engineering,chemical engineering,and biochemical engineering.Numerous theoretical analyses,numerical simulations,and experimental studies have been conducted to reveal the mysteries of bubble motion and its mechanisms.These efforts have significantly advanced research in bubble dynamics,where theoretical study is an efficient method for bubble motion prediction.Since Lord Rayleigh introduced the theoretical model of single-bubble motion in incompressible fluid in 1917,theoretical studies have been pivotal in understanding bubble dynamics.This study provides a comprehensive review of the development and applicability of theoretical studies in bubble dynamics using typical theoretical bubble models across different periods as a focal point and an overview of bubble theory applications in underwater explosion,marine cavitation,and seismic exploration.This study aims to serve as a reference and catalyst for further advancements in theoretical analysis and practical applications of bubble theory across marine fields.
基金supported by the National Natural Science Foundation of China(Nos.22136003 and 21972073)the Opening foundation of the Engineering Research Center of Ecoenvironment in Three Gorges Reservoir Region,Ministry of Education(No.KF2023-01)the Natural Science Foundation of Yichang City(No.A22-3-005)。
文摘The synergetic technology of hydrodynamic cavitation(HC)and peroxydisulfate(PDS)has been adopted for the treatment of organic pollutants,while the rationale behind the thermal-activation of PDS in this process remains lacking.This paper presented investigation on the degradation of tetracycline under two types of operating conditions,including“internal reaction conditions”(pH value and TC/PDS molar ratio)and“external physical conditions”(hole shape,solution temperature and inlet pressure).Special emphasis was paid on the analysis of thermal effects through a robust modeling approach.The results showed that a synergy index of 6.26 and a degradation rate of 56.71%could be obtained by the HC-PDS process,respectively,when the reaction conditions were optimized.Quenching experiment revealed that·OH and·SO_(4)^(-)were the predominant free radicals and their contribution to the degradation was 75.4%and 24.6%respectively,since a part of·SO_(4)^(-)was transformed into·OH in the solution.The thermal activation of PDS mainly occurred near the hole where the fitting temperature was around 340 K,while·OH was generated in the bubble collapse region downstream the hole,where the temperature was much higher and favorable for the cleavage of water molecular.The average temperature under different external physical conditions was in good consistence with the degradation rates.This research developed a useful method to effectively evaluate the activation extent of PDS by HC and could provide reliable guidance for further development of cavitational reactors to treat organic pollutants based on this hybrid approach.
基金supported by the National Natural Science Foundation of China(Grant No.12172178).
文摘In this paper,the load characteristics of shock wave,bubble pulsating water jet and cavitation closure are studied by carrying out underwater explosion experiments and numerical simulation of fixed square plates with 2.5,5 and 10 g trinitrotoluene.The results show that under the combined action of multiple loads,the impulse of bubble pulsation and water jet load plays a leading role in the process of underwater explosion,and the impulse of cavitation closure load is greater than that of shock wave.The damage to the structure cannot be ignored,and the pressure time-history curve presents a“multi-peak”state,and it is pointed out that the water jet is a concentrated load.Then,the dynamic response of the full-scale model of the ship under the combined action of multiple loads is studied,and the dynamic response of the ship under different cabin water depths and different explosion distances is discussed.The results show that when the ship is empty,the damage degree of the ship is the most serious,and the influence of cavitation effect on the half cabin is weaker than that of the empty cabin,so the damage degree is the second,and the damage degree is the smallest when the cabin is full.When the distance parameter is less than 0.68,the shock wave and the after flow play a leading role in the dynamic response of the ship.When the distance parameter is between 0.68 and 1.38,the combined action of the bubble pulsating water jet and the cavitation closure multi-load causes the main damage to the ship.When the distance parameter is greater than 1.38,the bubble pulsation and the cavitation closure load play a leading role.
基金supported by the National Natural Science Foundation of China(Grant No.52171261).
文摘A floating horizontal-axis tidal current turbine(HATT)is an underwater power generation device where cavitation inevitably occurs on blade surfaces,severely affecting a turbine’s lifespan.Under wave action,these floating turbines exhibit six degrees of freedom motion,potentially intensifying the cavitation on the blade surfaces.This study selects three types of oscillatory motions from the six degrees of freedom:roll,yaw,and pitch.Computational fluid dynamics(CFD)methods are used for numerical calculations,and transient simulations of multiphase flow are conducted on the basis of the Reynolds-Averaged Navier-Stokes(RANS)model.Research has revealed strong correlations between flow velocity,the blade tip speed ratio,and cavitation.During oscillatory motion,the motion period and amplitude also significantly impact cavitation.In roll motion,the cavitation rate can increase by up to 59%with decreasing period,whereas in pitch and yaw motions,the increases are 7.57 times and 36%larger,respectively.With an increase in amplitude during roll motion,the cavitation rate can increase by up to 1.08 times,whereas in pitch and yaw motions,the increases are 3.49 times and 45%,respectively.The cavitation rate on the blade surfaces is the highest in pitch motion,followed by roll and yaw motions.
基金Funded by the National Natural Science Foundation of China(52066011)Jiuquan Science and Technology Plan Project University-Level Key Project(2024XJKXM03)Foundation of Key Laboratory of Solar Power System(Grant No.2024SPKL03).
文摘Bulb-type hydro turbines are commonly used in small-to medium-scale hydropower stations due to their compact design and adaptability to low-head conditions.However,long-termoperation often results in wear at the runner rim,increasing tip clearance and triggering leakage flow and cavitation.These effects reduce hydraulic efficiency and accelerate blade surface erosion,posing serious risks to unit safety and operational stability.This study investigates the influence of tip clearance on cavitation performance in a 24 MW prototype bulb turbine.A three-dimensional numericalmodel is developed to simulate various operating conditions with different tip clearance values(3.0,4.5,and 6.0 mm)and cavitation numbers(σ=1.20–1.33).Internal flow characteristics—including pressure distribution,velocity fields,hydraulic efficiency,and pressure pulsation—are analyzed to elucidate the impact of tip clearance on cavitation development.Results show that underσ=1.2 and a 4.5 mm tip clearance,the pressure pulsation amplitude at the blade tip reaches 4870 Pa—approximately 1.5 times higher than that near the hub.At partial flowconditions,turbine efficiency decreases by up to 6.8%compared to the rated condition.Increasing the tip clearance from 1.5 to 6.0 mm expands the low-pressure area near the blade tip by around 32%,significantly intensifying cavitation.Frequency domain analysis reveals dominant pulsation frequencies between 10–20Hz,characterized by blade-passing features and a wave-clipping effect.These findings provide theoretical insight and quantitative evidence to support the optimization of tip clearance design and cavitation mitigation strategies in bulb turbines,aiming to improve both efficiency and operational stability.
基金financial support of the National Natural Science Foundation of China(Nos.52101105 and 52271319)the Jiangsu Provincial Science and Technology Program(BK20231525).
文摘The corrosion and cavitation erosion(CE)behavior of Co-6Ti-11V-9Cr alloy are investigated in both deionized water and 3.5 wt.%NaCl solution.Utilizing electrochemical methods and CE testing,the research aims to clarify the synergistic effects of CE and corrosion.The results demonstrate that after 8 h of CE exposure,Co-6Ti-11V-9Cr alloy experienced a cumulative mass loss of 1.84 mg in deionized water and 3.42 mg in NaCl solution,leading to mass loss rates of 0.23 and 0.43 mg/h,respectively.In NaCl solution,CE was responsible for 53.8%of the overall damage,with the remaining damage attributed to the combined influences of corrosion and CE.Under CE conditions,both the corrosion potential and corrosion current density of the alloy increased,which accelerated the corrosion process and exacerbated cavitation damage.The material sustained more severe damage in 3.5 wt.%NaCl solution over the same cavitation durations.Ultimately,CE damage mechanism of Co-6Ti-11V-9Cr superalloy was elucidated based on relevant experimental observations.
基金supported by Chongqing Natural Science Foundation Innovation and Development Joint Fund(CSTB2023NSCQ-LZX0095)Chongqing Natural Science Foundation General Project(CSTB2025NSCQ-GPX0955)+3 种基金Science and Technology Research Program of Chongqing Municipal Education Commission of China(KJQN202401157)The Open and Innovation Fund of Hubei Three Gorges Laboratory(SK250005)The Key Laboratory of Manufacturing and Application of Intelligent Well Control for Oil and Gas Production and Transportation of Luzhou(2024LZOGB-05)postgraduate Innovation Project of Chongqing University of Technology(CYS240709).
文摘With the acceleration of industrialization and urbanization,ammonia nitrogen pollution in water bodies has become increasingly severe,making the development of efficient and low-consumption wastewater treatment tech-nologies highly significant.This study employs three-dimensional computational fluid dynamics(CFD)to investigate the cavitation mechanisms and flow field characteristics in a novel jet impingement-negative pressure ammonia removal reactor.The simulation,validated by experimental pressure data with a high degree of consistency,utilizes the Mixture model,the Realizable k-εturbulence model,and the Schnerr-Sauer cavitation model.The results demonstrate that the flow velocity undergoes a substantial acceleration within the orifice nozzle,triggering a dramatic pressure drop from an inlet value of approximately 1.17 MPa to below the saturated vapor pressure,reaching as low as−109 kPa,which induces intense cavitation.Cavitation bubbles primarily originate on the inner wall of the nozzle,with the vapor volume fraction peaking at about 0.42 within the orifice.A strong positive correlation was observed between the local vapor fraction and the flow velocity,indicating that cavitation enhances jet intensity.Furthermore,vortex structures near the wall and within the jacket sustain low-pressure zones,facilitating continuous cavitation and efficient mixing.This study quantitatively elucidates the cavitation dynamics and its interplay with the flow field,providing a solid theoretical and numerical basis for optimizing the reactor design to enhance ammonia removal efficiency.
基金supported by the Higher Education Science and Technology Innovation Project of Shanxi Province(No.2022L706)Natural Science Foundation of Jiangsu Province(No.BK20210755).
文摘Polymer microfluidic chips are a common tool in biomedical research,and the production of mold inserts with microscale structures represents a crucial step in the precise molding of these chips.Electrical discharge machining(EDM)can achieve high-quality machining of microstructures on high-hardness mold steel inserts.This can reduce the manufacturing cost of microfluidic chip molds and extend the service life of molds.However,the EDM process is susceptible to the formation of poor-quality surfaces due to the occurrence of abnormal discharges.To address this issue,this paper presents in-depth research on a novel ultrasonic cavitation-assisted electrical discharge machining method.An ultrasonic transducer is placed in an electrical discharge working fluid to promote the removal of electrical corrosion products through the cavitation effect of the liquid.This can also reduce the occurrence of poor discharge,thereby improving the machining surface quality.The aluminum foil corrosion method is employed to investigate the distribution of ultrasonic action in the electric discharge working fluid.The attenuation law of ultrasonic action in the electric discharge working fluid is also investigated.The range of ultrasonic action is determined,providing a reference for subsequent ultrasonic vibration electric discharge working fluid processing experiments.The results of the aluminum foil tests are used to inform the selection of NAK80 mold steel as the experimental object.The effects of cavitation at three ultrasonic frequencies on the surface microstructure are investigated.The experimental results indicate that ultrasonic cavitation can facilitate the movement of corrosion products in electrical machining,reduce the occurrence of abnormal discharges caused by carbon deposition or the secondary re-melting of metals,and thereby enhance the machining surface quality.
基金sponsored by the Vietnam Academy of Science and Technology(VAST),granted to Prof.Duong Ngoc Hai under Project No.VAST01.02/22-23by the National Research Foundation(NRF)of the Republic of Korea,granted to Prof.Warn-Gyu Park under Project No.RS-2023-00248070.
文摘This study presents a numerical analysis of the effects of a rigid flat wall with oscillating motion on the pressure wave propagation during a single spherical cavitation bubble collapse at different initial bubble positions.Different nondimensional distances S=0.8,0.9,1.0,1.1,1.2 and 1.3 were considered to investigate the effects of initial in-phase and out-of-phase oscillations of the flat wall.Numerical simulations of cavitation bubble collapse near an oscillating wall were conducted using a compressible two-phase flow model.This model incorporated the Volume of Fluid(VOF)interface-sharpening technique on a general curvilinear moving grid.The numerical results were consistent with published experimental data.The simulation examined the impact of oscillating walls on bubble behavior and the resulting pressure peaks observed on the wall surface.The numerical results demonstrate the significant impact of wall oscillation conditions on bubble collapse and migration behavior,and consequently,the generation of pressure waves with significantly different propagation and pressure peaks induced by shock impact on the rigid wall.Different behaviors were observed in the trendlines of the pressure peaks and maximum jet velocity under in-phase and out-of-phase oscillating walls,with distinct values.At S≥1.0,a higher-pressure peak on the wall was observed in the case of the out-of-phase oscillating condition,whereas a higher-pressure peak was found in the case of the in-phase condition at S<1.0.The highest-pressure peak was found at S=0.8 in trend lines of in-phase and S=1.1 in trend lines of out-of-phase oscillation effects.
基金supported by the Doctoral Fund Program of Longdong University(Grant No.XYBYZK2219)the National Natural Science Foundation of China(Grant No.12274277)+1 种基金the Science and Technology Project of Gansu Province of China(Grant No.21JR11RM046)Young Doctor Fund of Gansu Education Department(Grant No.2022QB-171).
文摘In order to enhance the ultrasonic degradation rate of organic solutions,a metal plate is placed at the water–air interface of the ultrasonic cleaning tank.Initially,the distribution of the acoustic field in the ultrasonic water tank was calculated using the simulation software COMSOL.The simulation results demonstrated that the utilization of the metal plate can eliminate the standing-wave acoustic field to a certain extent.Subsequently,the pixel method was selected for a quantitative comparison of the cavitation area in the flume with and without the metal plate.The results demonstrated that,under specific conditions,the area of ultrasonic cavitation in the water tank can be expanded using a metal plate.Thereafter,an acoustic degradation experiment was designed to confirm the feasibility of the simulation method.Furthermore,the impacts of the amplitude of the incident ultrasonic pressure,frequency,and the height of the liquid level in the water tank on the cavitation area were investigated.
基金financially supported by the National Natural Science Foundation of China(No.52031007).
文摘Selective laser melting(SLM),a laser-powder bed fusion(L-PBF)additive manufacturing technique,demonstrates significant potential for enhancing the mechanical performance of Al-Si alloys.In this study,three representative hypoeutectic Al-Si alloys(AlSi7Mg,AlSi10Mg,and AlSi12)were fabricated via SLM additive manufacturing to systematically investigate the influence of silicon content on microstructural evolution and mechanical properties.Advanced characterization techniques including scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),and transmission electron microscopy(TEM)were employed to systematically examine the cavitation erosion behavior of additive-manufactured Al-Si(AM Al-Si)alloys.The experimental findings reveal that varying silicon content predominantly alters the morphology and dimensions of the silicon network structure in AM Al-Si alloys,particularly through modulation of cellular silicon wall thickness.This microstructural modification was identified as the primary determinant in enhancing cavitation erosion(CE)resistance,with the refined silicon network architecture effectively impeding crack propagation and phase boundary delamination under CE conditions.
基金supported by the Innovative Research Team Development Program of Ministry of Education of China(No.IRT_17R83)State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology,China(No.P2021-018).
文摘In order to reveal the cavitation erosion mechanisms of Fe_(50)Mn_(30)Co_(10)Cr_(10)coating prepared by laser melting deposition(LMD)technique,the phase composition evolution,microstructure,microhardness,cavitation erosion resistance and failure mechanisms were investigated.The results demonstrate that the amount of martensite HCPεphase of the coating surface increased by a factor of 2.43,and the microhardness increased from HV 270 to HV 410 after 20 h of cavitation erosion test in distilled water.The cumulative volume loss of the coating was approximately 55%less than that of AlCoCrxCuFe(x=2.0),and the cumulative mean depth of erosion(MDE)was 9%that of FeCoCrAlNiTix(x=2.0).The surface strength and plasticity of the coating were further strengthened in the process of cavitation erosion due to the back stress strengthening and work hardening mechanism caused by the heterogeneous structure,which effectively improved the cavitation erosion resistance of the coating.
基金National Natural Science Foundation of China(51139007)National “Twelfth Five-Year” Plan for Science&Technology Support(2015BAD20B01)China Scholarship Council(201506350088)
文摘The cavitation incipience and development of water flow over a thin hydrofoil placed in the test section of high-speed cavitation tunnel were investigated.Hydrofoils with smooth and rough leading edge were tested for different upstream velocities and incidence angles.The observations clearly revealed that cavitation incipience is enhanced by roughness at incidence angle below 2°.This is in line with the former reports,according to whose roughness element decreases the wettability and traps a larger amount of gas.As a result,surface nucleation is enhanced with an increased risk of cavitation.Surprisingly,for higher incidence angles(>3°),it was found that cavitation incipience is significantly delayed by roughness while developed cavitation is almost the same for both smooth and rough hydrofoils.This unexpected incipience delay is related to the change in the boundary layer structure due to roughness.It was also reported a significant influence of roughness on the dynamic of developed cavitation and shedding of transient cavities.
文摘A transient multiphase CFD （computational fluid dynamics） model was set up to investigate the main causes which lead to cavitation in PD （positive displacement） reciprocating pumps. Many authors agree on distinguishing two different types of cavitation affecting PD pumps： flow induced cavitation and cavitation due to expansion. The flow induced cavitation affects the zones of high fluid velocity and consequent low static pressure e.g. the valve-seat volume gap while the cavitation due to expansion can be detected in zones where the decompression effects are important e.g. in the vicinity of the plunger. This second factor is a distinctive feature of PD pumps since other devices such as centrifugal pumps are only affected by the flow induced type. Unlike what has been published in the technical literature to date, where analysis of positive displacement pumps are based exclusively on experimental or analytic methods, the work presented in this paper is based entirely on a CFD approach, it discusses the appearance and the dynamics of these two phenomena throughout an entire pumping cycle pointing out the potential of CFD techniques in studying the causes of cavitation and assessing the consequent loss of performance in positive displacement pumps.
基金Supported by National Nature Science Foundation of China(Grant No.51575245)Jiangsu Provincial Key research and development program(Grant No.BE2015134)Zhenjiang Municipal Key Research and Development Project(Grant No.KZ2020001).
文摘Cavitation generation methods have been used in multifarious directions because of their diversity,and numerous studies and discussions have been conducted on cavitation generation methods.This study aims to explore the generating mechanism and evolution law of volume alternate cavitation(VAC).In the VAC,liquid water is placed in an airtight container with a variable volume.As the volume alternately changes,the liquid water inside the container continues to cavitate.Then,the mixture turbulence model and in-cylinder dynamic grid model are adopted to conduct computational fluid dynamics simulation of volume alternate cavitation.In the simulation,the cloud images at seven heights on the central axis are monitored,and the phenomenon and mechanism of height and eccentricity are analyzed in detail.By employing the cavitation flow visualization method,the generating mechanism and evolution law of cavitation are revealed.The synergistic effects of experiments and high-speed camera capturing confirm the correctness of the simulation results.In the experiment,the volume change stroke of the airtight container is set to 20 mm,the volume change frequency is 18 Hz,and the shooting frequency of the high-speed camera is set to 10000 FPS.The experimental results indicate that the position of the cavitation phenomenon has a reasonable law during the whole evolution cycle of the cavitation cloud.Also,the volume alternation cycle corresponds to the generation,development,and collapse stages of cavitation bubbles.
基金Project(50479016) supported by the National Natural Science Foundation of China
文摘Conventional,submicron and multimodal WC-12Co cermet coatings were deposited by high velocity oxy-fuel（HVOF）.The microhardness and microstructure of the coatings were compared,and the resistance of the coatings to cavitation erosion was studied by ultrasonic vibration cavitation equipment.Cavitation pits and craters were observed by SEM and cavitation mechanisms were explored.The results show that the microstructures of submicron and multimodal WC-12Co coatings prepared by HVOF are dense with little porosity,and their microhardness values are obviously higher than that of the conventional WC-12Co coating.The average microhardness of multimodal WC-12Co coating reaches nearly HV1500,which is much higher than that of the conventional one.As well,it is found that the multimodal WC-12Co coating exhibits the best cavitation erosion resistance among the three coatings,the erosion rate is approximately 40% that of the conventional coating,and the cavitation erosion resistance of multimodal WC-12Co coating is enhanced by above 150% in comparison with the conventional coating.
