Scouring experiments were conducted using a three-dimensional laser scanning technology for angles of the jet spanning the interval from 0°to 30°,and the characteristics of the scour hole in equilibrium cond...Scouring experiments were conducted using a three-dimensional laser scanning technology for angles of the jet spanning the interval from 0°to 30°,and the characteristics of the scour hole in equilibrium conditions were investigated accordingly.The results indicate that the optimal scouring effects occur when the jet angle is in the ranges between 15°and 20°.Moreover,the dimensionless profiles of the scour hole exhibit a high degree of similarity at different jet angles.Numerical simulations conducted using the Flow-3D software to investigate the bed shear stress along the jet impingement surface have shown that this stress is influenced by both the resultant force and the jet impingement surface area.It reaches its maximum value when the jet is vertical,decreases rapidly as the jet starts to tilt,then increases slightly,and decreases again significantly when the angle exceeds 20°.展开更多
To develop and utilize marine resources in the deep sea, the higher requirements for floating structures, which are operated in marine environment for a long term, have been put forward. Reasonable structure type and ...To develop and utilize marine resources in the deep sea, the higher requirements for floating structures, which are operated in marine environment for a long term, have been put forward. Reasonable structure type and accurate force analysis are favorable guarantees to improve the survival performance and working performance of the floating structures. Floating spheres fastened by mooring cable were widely used in floating structures. In this paper, the wave forces of the floating sphere are efficiently and accurately calculated by solving the geometric relationship between the non-submerged floating sphere and wave surface. Combined with the hydrodynamic calculation of mooring cables based on the lumped mass method, the coupled motion model of multi-floating spheres fastened by multi-mooring cable was established under wave action. Furthermore, according to the floating structures fastened by mooring cable in the actual ocean engineering, the topological method of multi-mooring cables fastening the multifloating spheres was expounded from simple to complex. Finally, the modeling method and preliminarily hydrodynamic characteristics of the fastened floating structures, including the mooring system of renewable energy devices, ocean buoy, and coral nursery, were presented and analyzed in detail. The obtained results showed that the method for calculating the wave force on the floating sphere developed in this paper can accurately describe the motion process of the floating mooring sphere and the force on the mooring cable. Also, the topological method of multiple buoys and multiple mooring cables could efficiently establish various numerical hydrodynamic models of fastened buoys in ocean engineering.展开更多
Water jet technology is widely used in submerged buried pipes as a non-traditional trenching process,often invol-ving a complex sediment response.An important adjustable and influential engineering variable in this tec...Water jet technology is widely used in submerged buried pipes as a non-traditional trenching process,often invol-ving a complex sediment response.An important adjustable and influential engineering variable in this technol-ogy is represented by the impinging distance.In this study,the FLOW-3D software was used to simulate the jet scouring of sand beds in a submerged environment.In particular,four sets of experimental conditions were con-sidered to discern the relationship between the maximum scour depth and mass and the impinging distance.As shown by the results,a critical impinging distance h0 exists by which the static scour depth can be maximized;the scour mass ratio between dynamic and static conditions decreases as the impinging distance increases.Moreover,the profile contours are similar when the erosion parameter Ec is in the range 0.35<Ec<2.Empirical equations applicable for predicting the jet trenching contour under both dynamic and static scour modes are also provided in this study.展开更多
In this study,the frequency characteristics of the turbulent wind and the effects of wind-wave coupling on the low-and high-frequency responses of semi-submersible floating offshore wind turbines(FOWT)are investigated...In this study,the frequency characteristics of the turbulent wind and the effects of wind-wave coupling on the low-and high-frequency responses of semi-submersible floating offshore wind turbines(FOWT)are investigated.Various wave load components,such as first-order wave loads,combined first-and second-order difference-frequency wave loads,combined first-and second-order sum-frequency wave loads,and first-and complete second-order wave loads are taken into consideration,while different turbulent environments are considered in aerodynamic loads.The com-parison is based on time histories and frequency spectra of platform motions and structural load responses and statistical values.The findings indicate that the second-order difference-frequency wave loads will significantly increase the natural frequency of low-frequency motion in the responses of the platform motion and structure load of the semi-submersible platform,which will cause structural fatigue damage.Under the action of turbulent wind,the influences of second-order wave loads on the platform motion and structural load response cannot be ignored,especially under extreme sea conditions.Therefore,in order to evaluate the dynamic responses of semi-submersible FOWT more accurately,the actual environment should be simulated more realistically.展开更多
Fluidization mechanism of liquefiable cargo is similar to that of sand liquefaction.But the cargo is subjected to more complex external loads during sea transportation.Based on two different constitutive models,numeri...Fluidization mechanism of liquefiable cargo is similar to that of sand liquefaction.But the cargo is subjected to more complex external loads during sea transportation.Based on two different constitutive models,numerical predictions were conducted in this study.And the effects of ship motions including motion acceleration,frequency and relative density of cargo on fluidization was investigated.By comparing with available the experimental data,validation is carried out.Results show that the roll motion is the most important one related to cargo fluidization.When the motion acceleration increases,the possibility of cargo fluidization increases.The higher of the cargo density the lower of the possibility of cargo fluidization.The effect of frequency on cargo fluidization is not unique,and it exists a critical value.The fluidization behavior of cargo could be described both by UBCSAND and FINN models.And the comparisons were discussed and summed up.展开更多
The removal effect of sunset yellow by the activated carbon prepared by modified straw was studied, and the effects of adsorption temperature, adsorption time, adsorption capacity, solution salinity and solution pH on...The removal effect of sunset yellow by the activated carbon prepared by modified straw was studied, and the effects of adsorption temperature, adsorption time, adsorption capacity, solution salinity and solution pH on the removal effect of sunset yellow were analyzed. After being soaked in acid and alkali, the stalks and leaves of the straw were carbonized and modified at 200-700 ℃. The results show that the adsorption effect of the leaves soaked in alkali was the best when the carbonization temperature was 700 ℃. As the adsorption temperature was 30-40 ℃, the adsorption effect of sunset yellow was the best. With the increase of adsorption time, the removal rate of sunset yellow first increased, then decreased, and finally rose again. The first critical point was about 30 min. When the dosage of activated carbon was 0.7 g, the adsorption effect of 50 ml of sunset yellow solution was the best. The optimal solution salinity was 60%. pH had a small effect on the adsorption of sunset yellow, showing a fluctuating trend.展开更多
The interface deformation and liquid breakup in vapor-liquid two-phase flow are ubiquitous in natural phenomena and industrial applications.It is crucial to understand the corresponding mechanism correctly.The droplet...The interface deformation and liquid breakup in vapor-liquid two-phase flow are ubiquitous in natural phenomena and industrial applications.It is crucial to understand the corresponding mechanism correctly.The droplet and liquid ligament dynamic behaviors are investigated in this work by simulating three benchmark cases through adopting a three-dimensional(3D)phase-field-based lattice Boltzmann model,and vapor-liquid phase interface deformation and liquid breakup mechanisms including the capillary instability and end-pinching mechanism are analyzed.The analysis results show that the capillary instability is the driving mechanism of the liquid breakup and the secondary droplet production at a large Weber number,which is different from the Rayleigh-Taylor instability and Kelvin-Helmholtz instability characterizing the vapor-liquid interface deformation.In addition,as another liquid breakup mechanism,the end-pinching mechanism,which describes the back-flow phenomenon of the liquid phase,works at each breakup point,thus resulting in capillary instability on the liquid phase structure.In essence,it is the fundamental mechanism for the liquid breakup and the immanent cause of capillary instability.展开更多
Aiming at the problem of inversion shallow seabed layered structure and geoacoustic parameter inversion with ship radiated noise as the reference sound source,a shallow sea multi-layered seabed geoacoustic parameter i...Aiming at the problem of inversion shallow seabed layered structure and geoacoustic parameter inversion with ship radiated noise as the reference sound source,a shallow sea multi-layered seabed geoacoustic parameter inversion method based on Bayesian theory is studied.In the inversion,the line spectrum component of the ship radiated noise is the research object,and then the nonlinear Bayesian inversion method is used to invert the seabed structure,the wave speed in the layer,the wave speed attenuation and the density,and the uncertainty of the inversion result is analyzed.The maximum a posteriori(MAP)estimate and the marginal probability distribution of the inversion result are calculated by the optimized simulated annealing(OSA)and Metropolis-Hastings sample(MHS)method in the prior interval of each parameter,and the best seabed layering is determined according to the Bayesian information criterion(BIC).The sea experiments show that the seabed layered structure and geoacoustic parameters are obtained by inversion according to this method,and the error between the calculated sound pressure field and the measured ship radiated noise transmission loss not exceed 10%,and the inversion result can accurately represent the seabed characteristics of the experimental sea area.The uncertainty of the inversion results shows that the uncertainty of compression wave speed,shear wave speed and density is smaller,and it is more sensitive to changes in the sound pressure field,and the inversion result is more effective and accurate.展开更多
To avoid resource wastage and secondary environmental pollution,recycling and reusing waste wood powder is still a great challenge.Moreover,the poor viscosity and irregular pore size of wood powder limit its practical...To avoid resource wastage and secondary environmental pollution,recycling and reusing waste wood powder is still a great challenge.Moreover,the poor viscosity and irregular pore size of wood powder limit its practical application.This study,employed a green and convenient wood powder reconstitution strategy to achieve highly adhesive bonding and pore size control between wood powder particles,thus preparing a high-strength and super hydrophilic wood powder membrane.The wood powder fibers were partially dissolved and regenerated to create a reconstituted wood powder hydrogel membrane,using waste wood powder as the raw material.The wood powder reconstitution strategy offers advantages such as environmental friendliness,simplicity,cost-effectiveness,and strong universality.Furthermore,the materials exhibit excellent self-cleaning properties and superhydrophilicity.Driven by gravity,the membrane can purify oily wastewater and dyes.Additionally,the reconstitution strategy offers a new pathway for recycling wood powder.展开更多
Polyhedral distortion,associated closely with the atomic arrangement and interatomic interactions,drives many unique behaviors in solids,such as phase transition and negative thermal expansion.In thermoelectric hetero...Polyhedral distortion,associated closely with the atomic arrangement and interatomic interactions,drives many unique behaviors in solids,such as phase transition and negative thermal expansion.In thermoelectric heteroanionic oxides,the anionic polyhedra are widely present,but their effect on thermal transport is rarely investigated.Here,we report an anomalous thermal conduction induced by local symmetry distortion in layered oxyselenides via solving the Boltzmann transport equation based on first-principles calculations.We found interestingly that lighter BiCuSeO exhibits lower thermal conductivity than heavier BiAgSeO.Due to the different distorted degrees of CuSe4 and AgSe4 tetrahedrons,Cu prefers the in-plane vibration,while Ag has more tendency of out-of-plane vibration.Thus,the heat-carrying phonons dominated by the rattling-like vibration of Cu are significantly suppressed,resulting in lower thermal conductivity of BiCuSeO.This study highlights the importance of polyhedral distortion in regulating thermal conduction in layered heteroanionic materials.展开更多
基金supported by Research on the Influence of Nozzle Structure on the Scouring Effect of Submerged Water Jet(2023R411045)Design and Control Strategy Research of PEM Fuel Cell Hybrid Propulsion System for Ships(2024R411015)+1 种基金Zhejiang Ocean University Outstanding Master’s Thesis Cultivation Project(ZJOUYJS20230018)General Program of Education Department of Zhejiang Province(Y202250817)which was gained by Chen.
文摘Scouring experiments were conducted using a three-dimensional laser scanning technology for angles of the jet spanning the interval from 0°to 30°,and the characteristics of the scour hole in equilibrium conditions were investigated accordingly.The results indicate that the optimal scouring effects occur when the jet angle is in the ranges between 15°and 20°.Moreover,the dimensionless profiles of the scour hole exhibit a high degree of similarity at different jet angles.Numerical simulations conducted using the Flow-3D software to investigate the bed shear stress along the jet impingement surface have shown that this stress is influenced by both the resultant force and the jet impingement surface area.It reaches its maximum value when the jet is vertical,decreases rapidly as the jet starts to tilt,then increases slightly,and decreases again significantly when the angle exceeds 20°.
基金financially supported by the National Natural Science Foundation of China (Grant No.52101330)the Basic Scientific Research Foundation of Zhejiang Provincial Universities (Grant No.2022J004)。
文摘To develop and utilize marine resources in the deep sea, the higher requirements for floating structures, which are operated in marine environment for a long term, have been put forward. Reasonable structure type and accurate force analysis are favorable guarantees to improve the survival performance and working performance of the floating structures. Floating spheres fastened by mooring cable were widely used in floating structures. In this paper, the wave forces of the floating sphere are efficiently and accurately calculated by solving the geometric relationship between the non-submerged floating sphere and wave surface. Combined with the hydrodynamic calculation of mooring cables based on the lumped mass method, the coupled motion model of multi-floating spheres fastened by multi-mooring cable was established under wave action. Furthermore, according to the floating structures fastened by mooring cable in the actual ocean engineering, the topological method of multi-mooring cables fastening the multifloating spheres was expounded from simple to complex. Finally, the modeling method and preliminarily hydrodynamic characteristics of the fastened floating structures, including the mooring system of renewable energy devices, ocean buoy, and coral nursery, were presented and analyzed in detail. The obtained results showed that the method for calculating the wave force on the floating sphere developed in this paper can accurately describe the motion process of the floating mooring sphere and the force on the mooring cable. Also, the topological method of multiple buoys and multiple mooring cables could efficiently establish various numerical hydrodynamic models of fastened buoys in ocean engineering.
基金supported by the Research on the Prediction Mechanism of Corrosion for High Strength Steel in Deep Sea Service Driven by Multi-Scale,High-Dimension and Small-Sample Data(C2301002635)Research on the Influence of Nozzle Structure on the Scouring Effect of Submerged Water Jet(2023R411045)+1 种基金the Zhejiang Ocean University Outstanding Master’s Thesis Cultivation Project(ZJOUYJS20230018)the Scientific Research Project of Zhejiang Graduate Education Society in 2022(2022-021)which was gained by Chen.
文摘Water jet technology is widely used in submerged buried pipes as a non-traditional trenching process,often invol-ving a complex sediment response.An important adjustable and influential engineering variable in this technol-ogy is represented by the impinging distance.In this study,the FLOW-3D software was used to simulate the jet scouring of sand beds in a submerged environment.In particular,four sets of experimental conditions were con-sidered to discern the relationship between the maximum scour depth and mass and the impinging distance.As shown by the results,a critical impinging distance h0 exists by which the static scour depth can be maximized;the scour mass ratio between dynamic and static conditions decreases as the impinging distance increases.Moreover,the profile contours are similar when the erosion parameter Ec is in the range 0.35<Ec<2.Empirical equations applicable for predicting the jet trenching contour under both dynamic and static scour modes are also provided in this study.
基金supported by the Natural Science Foundation of Zhejiang Province(Grant No.LHZ21E090003)the National Nature Science Foundation of China(Grant No.52171279)+1 种基金Zhoushan Science&Technology Project(Grant No.2021C21002)supported by CNPq(Conselho Nacional de Desenvolvimento Científico e Tecnológico,Grant No.301474/2017-6).
文摘In this study,the frequency characteristics of the turbulent wind and the effects of wind-wave coupling on the low-and high-frequency responses of semi-submersible floating offshore wind turbines(FOWT)are investigated.Various wave load components,such as first-order wave loads,combined first-and second-order difference-frequency wave loads,combined first-and second-order sum-frequency wave loads,and first-and complete second-order wave loads are taken into consideration,while different turbulent environments are considered in aerodynamic loads.The com-parison is based on time histories and frequency spectra of platform motions and structural load responses and statistical values.The findings indicate that the second-order difference-frequency wave loads will significantly increase the natural frequency of low-frequency motion in the responses of the platform motion and structure load of the semi-submersible platform,which will cause structural fatigue damage.Under the action of turbulent wind,the influences of second-order wave loads on the platform motion and structural load response cannot be ignored,especially under extreme sea conditions.Therefore,in order to evaluate the dynamic responses of semi-submersible FOWT more accurately,the actual environment should be simulated more realistically.
基金supported by the National Natural Science Foundation of China(Grant No.51809237)the Fundamental Research Funds for the Provincial Universities(Grant No.2021J017).
文摘Fluidization mechanism of liquefiable cargo is similar to that of sand liquefaction.But the cargo is subjected to more complex external loads during sea transportation.Based on two different constitutive models,numerical predictions were conducted in this study.And the effects of ship motions including motion acceleration,frequency and relative density of cargo on fluidization was investigated.By comparing with available the experimental data,validation is carried out.Results show that the roll motion is the most important one related to cargo fluidization.When the motion acceleration increases,the possibility of cargo fluidization increases.The higher of the cargo density the lower of the possibility of cargo fluidization.The effect of frequency on cargo fluidization is not unique,and it exists a critical value.The fluidization behavior of cargo could be described both by UBCSAND and FINN models.And the comparisons were discussed and summed up.
基金Supported by the Public Welfare Technology Research Project of Zhejiang Province (LGF20D060001)the National Natural Science Foundation of China (U1809214)。
文摘The removal effect of sunset yellow by the activated carbon prepared by modified straw was studied, and the effects of adsorption temperature, adsorption time, adsorption capacity, solution salinity and solution pH on the removal effect of sunset yellow were analyzed. After being soaked in acid and alkali, the stalks and leaves of the straw were carbonized and modified at 200-700 ℃. The results show that the adsorption effect of the leaves soaked in alkali was the best when the carbonization temperature was 700 ℃. As the adsorption temperature was 30-40 ℃, the adsorption effect of sunset yellow was the best. With the increase of adsorption time, the removal rate of sunset yellow first increased, then decreased, and finally rose again. The first critical point was about 30 min. When the dosage of activated carbon was 0.7 g, the adsorption effect of 50 ml of sunset yellow solution was the best. The optimal solution salinity was 60%. pH had a small effect on the adsorption of sunset yellow, showing a fluctuating trend.
基金the National Natural Science Foundation of China(Grant No.51776031)the Fundamental Research Funds for Zhejiang Provincial Universities and Research Institutes,Chinathe Key Project of Science and Technology Development of Henan Province,China(Grant No.222102220033)。
文摘The interface deformation and liquid breakup in vapor-liquid two-phase flow are ubiquitous in natural phenomena and industrial applications.It is crucial to understand the corresponding mechanism correctly.The droplet and liquid ligament dynamic behaviors are investigated in this work by simulating three benchmark cases through adopting a three-dimensional(3D)phase-field-based lattice Boltzmann model,and vapor-liquid phase interface deformation and liquid breakup mechanisms including the capillary instability and end-pinching mechanism are analyzed.The analysis results show that the capillary instability is the driving mechanism of the liquid breakup and the secondary droplet production at a large Weber number,which is different from the Rayleigh-Taylor instability and Kelvin-Helmholtz instability characterizing the vapor-liquid interface deformation.In addition,as another liquid breakup mechanism,the end-pinching mechanism,which describes the back-flow phenomenon of the liquid phase,works at each breakup point,thus resulting in capillary instability on the liquid phase structure.In essence,it is the fundamental mechanism for the liquid breakup and the immanent cause of capillary instability.
基金supported by the National Natural Science Foundation of China(11704337)National Defense Basic Research Program-Laboratory Stable Support Special Projects(JCKYS2020604SSJS011)Marine Science Zhejiang First-class Discipline Open Project(20200101)。
文摘Aiming at the problem of inversion shallow seabed layered structure and geoacoustic parameter inversion with ship radiated noise as the reference sound source,a shallow sea multi-layered seabed geoacoustic parameter inversion method based on Bayesian theory is studied.In the inversion,the line spectrum component of the ship radiated noise is the research object,and then the nonlinear Bayesian inversion method is used to invert the seabed structure,the wave speed in the layer,the wave speed attenuation and the density,and the uncertainty of the inversion result is analyzed.The maximum a posteriori(MAP)estimate and the marginal probability distribution of the inversion result are calculated by the optimized simulated annealing(OSA)and Metropolis-Hastings sample(MHS)method in the prior interval of each parameter,and the best seabed layering is determined according to the Bayesian information criterion(BIC).The sea experiments show that the seabed layered structure and geoacoustic parameters are obtained by inversion according to this method,and the error between the calculated sound pressure field and the measured ship radiated noise transmission loss not exceed 10%,and the inversion result can accurately represent the seabed characteristics of the experimental sea area.The uncertainty of the inversion results shows that the uncertainty of compression wave speed,shear wave speed and density is smaller,and it is more sensitive to changes in the sound pressure field,and the inversion result is more effective and accurate.
基金This work was supported by the Zhejiang Provincial Natural Science Foundation of China(No.LY23D060004)the Science and Technology Planning Project of Zhoushan of China(No.2022C41005)the National Natural Science Foundation of China(No.51606168).
文摘To avoid resource wastage and secondary environmental pollution,recycling and reusing waste wood powder is still a great challenge.Moreover,the poor viscosity and irregular pore size of wood powder limit its practical application.This study,employed a green and convenient wood powder reconstitution strategy to achieve highly adhesive bonding and pore size control between wood powder particles,thus preparing a high-strength and super hydrophilic wood powder membrane.The wood powder fibers were partially dissolved and regenerated to create a reconstituted wood powder hydrogel membrane,using waste wood powder as the raw material.The wood powder reconstitution strategy offers advantages such as environmental friendliness,simplicity,cost-effectiveness,and strong universality.Furthermore,the materials exhibit excellent self-cleaning properties and superhydrophilicity.Driven by gravity,the membrane can purify oily wastewater and dyes.Additionally,the reconstitution strategy offers a new pathway for recycling wood powder.
基金This work was financially supported by Basic Science Center Project of National Natural Science Foundation of China under grant No.51788104National Science Foundation of China under grant No.52172211+2 种基金The work at Henan Polytechnic University is supported by the Doctoral Foundation of Henan Polytechnic University(in Natural and Science)(NO.B202112)the Fundamental Research Funds for the Universities of Henan Province(NO.NSFRF220421)B.W.was partially supported by the postgraduate research opportunities program of HZWTECH(HZWTECH-PROP).
文摘Polyhedral distortion,associated closely with the atomic arrangement and interatomic interactions,drives many unique behaviors in solids,such as phase transition and negative thermal expansion.In thermoelectric heteroanionic oxides,the anionic polyhedra are widely present,but their effect on thermal transport is rarely investigated.Here,we report an anomalous thermal conduction induced by local symmetry distortion in layered oxyselenides via solving the Boltzmann transport equation based on first-principles calculations.We found interestingly that lighter BiCuSeO exhibits lower thermal conductivity than heavier BiAgSeO.Due to the different distorted degrees of CuSe4 and AgSe4 tetrahedrons,Cu prefers the in-plane vibration,while Ag has more tendency of out-of-plane vibration.Thus,the heat-carrying phonons dominated by the rattling-like vibration of Cu are significantly suppressed,resulting in lower thermal conductivity of BiCuSeO.This study highlights the importance of polyhedral distortion in regulating thermal conduction in layered heteroanionic materials.
