Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied throug...Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied through theoretical analysis,experimentand field measurement.The results show that high-pressure pulsed water jet has threedynamic properties.What's more,the three dynamic effects can be found in low-permeabilitycoal seams.A new pulsed water jet with 200-1 000 Hz oscillation frequency andpeak pressure 2.5 times than average pressure was introduced.During bubble collapsing,sound vibration and instantaneous high pressures over 100 MPa enhanced the cuttingability of the high-pressure jet.Through high-pressure pulsed water jet drilling and slotting,the exposure area of coal bodies was greatly enlarged and pressure of the coal seamsrapidly decreased.Therefore,the permeability of coal seams was improved and gas absorptionrate also decreased.Application results show that gas adsorption rate decreasedby 30%-40%and the penetrability coefficient increased 100 times.This proves that high-pressurepulsed water is more efficient than other conventional methods.展开更多
The Mg–Zn–Gd alloy with quasicrystal icosahedral phase was processed by high-pressure torsion (HPT). The effect of bimodal I-phase on the dynamic recrystallization was analyzed by transmission electron microscopy. T...The Mg–Zn–Gd alloy with quasicrystal icosahedral phase was processed by high-pressure torsion (HPT). The effect of bimodal I-phase on the dynamic recrystallization was analyzed by transmission electron microscopy. The results showed that the block I-phase can stimulate obvious particle-stimulated nucleation and dynamic recrystallization (DRX) grains were preferentially formed after HPT for 5 turns, while the granular I-phase only promoted the generation of sub-grains. The orientation relationship was determined as twofold//[1210] and fivefold//(0002)_(Mg). Moreover, after HPT for 9 turns, the DRX grains induced by block I-phase appeared to grow up and coarsened. Compared with block I-phase, the grains induced by granular I-phase presented much smaller size and distributed more homogeneous due to the strong pinning effect.展开更多
To improve energy density,the transportation,storage,and operations of hydrogen,methane,and compressed air vehicles currently require high-pressure compression.High-pressure solenoid valve becomes the vital element to...To improve energy density,the transportation,storage,and operations of hydrogen,methane,and compressed air vehicles currently require high-pressure compression.High-pressure solenoid valve becomes the vital element to above system.In order to reduce leakage and aerodynamic force influence,a new type high-pressure solenoid valve was proposed.The simulation model which included electromagnetic model,aerodynamic force model was established by means of the nonlinear mathematic models.Using the software MATLAB/Simulink for simulation,the dynamic response characteristics of high-pressure pneumatic solenoid valve were obtained under different pulse width modulation(PWM)input control signals.Results show that,first of all,the new type of high-pressure solenoid valve can meet the switch requirement.Secondly,the opening movement and closing movement of the spool lags the PWM rising signal,and the coil current fluctuates significantly during the movement of the spool.Lastly,on/off status of high-pressure valve cannot be represented by the duty cycle.This research can be referred in the design of the high-pressure solenoid valve..展开更多
In this work,an automated microfluidic chip that uses negative pressure to sample and analyze solutions with high temporal resolution was developed.The chip has a T-shaped channel for mixing the sample with a fluoresc...In this work,an automated microfluidic chip that uses negative pressure to sample and analyze solutions with high temporal resolution was developed.The chip has a T-shaped channel for mixing the sample with a fluorescent indicator,a flow-focusing channel for generating droplets in oil,and a long storage channel for incubating and detecting the droplets.By monitoring the fluorescence intensity of the droplets,the device could detect changes in solution accurately over time.The chip can generate droplets at frequencies of up to 42 Hz with a mixing ratio of 1:1 and a temporal resolution of 3–6 s.It had excellent linearity in detecting fluorescein solution in the concentration range 1–5μM.This droplet microfluidic chip provides several advantages over traditional methods,including high temporal resolution,stable droplet generation,and faster flow rates.This approach could be applied to monitoring calcium ions with a dynamic range from 102 to 107 nM and a detection limit of 10 nM.展开更多
Janus vesicles,unique nanostructures,have attracted significant attention for their diverse applications in biomedical and microfluidic systems.In practical micro-nano systems,flow and electric fields often coexist,an...Janus vesicles,unique nanostructures,have attracted significant attention for their diverse applications in biomedical and microfluidic systems.In practical micro-nano systems,flow and electric fields often coexist,and the perforation dynamics of Janus vesicles exhibit complex motion due to their synergistic effects.Studying Janus vesicle perforation dynamics under the combined influence of fluid flow and electric fields provides valuable insights into their applications in drug delivery,catalyst delivery,and controlled release.This study focuses on the perforation dynamics and directional motion of Janus vesicles in microchannels,emphasizing how electric field strength and charge distribution on the membrane influence vesicle migration,deformation,and trajectories.Results show that when electromagnetic forces and flow-driven forces align,increasing electric field strength promotes vesicle migration and perforation.Vesicle migration is correlated with charge distribution on the membrane,with broader distributions resulting in more pronounced migration.When electric field strength remains constant,charge distribution has little effect on vesicle deformation.Conversely,when electromagnetic forces and flow-driven forces oppose,increasing electric field strength inhibits vesicle migration.At a specific potential difference,charged vesicles cease movement before reaching the perforation site,indicating the critical potential for perforation.The study also reveals that the direction of the electric field significantly affects vesicle migration direction.Adjusting potential values at microchannel boundaries can control the directional movement of Janus vesicles.This research provides new insights into Janus vesicle behavior in complex environments and deepens understanding of their potential as drug carriers for delivery and targeted therapy.展开更多
High-pressure water jet technology has emerged as a highly effective method for removing industrial-scale deposits from pipelines,offering a clean,efficient,and environmentally sustainable alternative to conventional ...High-pressure water jet technology has emerged as a highly effective method for removing industrial-scale deposits from pipelines,offering a clean,efficient,and environmentally sustainable alternative to conventional mechanical or chemical cleaning techniques.Among the many parameters influencing its performance,the geometry of the nozzle plays a decisive role in governing jet coherence,impact pressure distribution,and overall cleaning efficiency.In this study,a comprehensive numerical and experimental investigation is conducted to elucidate the influence of nozzle geometry on the behavior of high-pressure water jets.Using Computational Fluid Dynamics(CFD)simulations based on the Volume of Fluid(VOF)approach,the jet dynamics and impingement characteristics of three representative nozzle configurations—flat,conical,and tapered—are systematically analyzed.Particular attention is devoted to the tapered nozzle,where variations in the outlet diameter are explored to determine their effect on flow structure,jet stability,and impact performance.The numerical predictions are rigorously validated against experimental measurements,demonstrating excellent quantitative agreement and confirming the robustness of the computational model.Results show that the tapered nozzle,characterized by its elongated conical transition section,promotes a more stable jet core and superior efflux performance compared to flat and conical geometries.Furthermore,the exit diameter is found to exert a profound influence on jet development.At an inlet pressure of 130 MPa,increasing the tapered nozzle's outlet diameter from 0.8 mm to 1.2 mm enlarges the coherent core region,enhances jet stability,and improves hydraulic energy utilization.Under these conditions,the total impact pressure on the target surface increases by 33.14%,while the overall cleaning efficiency improves by 40.44%.展开更多
Quantumdot inks(QDIs)represent an emerging functionalmaterial that integrates nanotechnology and fluid engineering,demonstrating significant application potential in flexible optoelectronics and high-color gamut displ...Quantumdot inks(QDIs)represent an emerging functionalmaterial that integrates nanotechnology and fluid engineering,demonstrating significant application potential in flexible optoelectronics and high-color gamut displays.Their wide applicability is due to a unique quantum confinement effect that enables precise spectral tunability and solution-processable properties.However,the complex fluid dynamics associated with QDIs at micro-/nano-scales severely limit the accuracy of inkjet printing and pattern deposition.This review systematically addresses recent advances in the hydrodynamics of QDIs,establishing scientific mechanisms and key technical breakthroughs from an interdisciplinary perspective.Current research has focused on three optimization directions:(1)regulating ligand structures to enhance colloidal stability,flow consistency,and anti-shear performance while mitigating nanoparticle aggregation;(2)incorporating low-viscosity or high-volatility solvents and surface tension modifiers to modify droplet dynamic characteristics and suppress the“coffee-ring”effect;(3)integrating advanced technologies such as electrohydrodynamic jetting and microfluidic targeted deposition to achieve submicron pattern resolution and high film uniformity,expanding adaptability in flexible electronics,biosensing,and anti-counterfeiting printing.A comparison of current technical routes and critical performance indicators has identified the dominant variables that influence QDI macroscopic/microscopic properties.A comprehensive analytical framework is presented which spans material structure,rheological behavior,manufacturing processes,and functional characteristics.Moreover,a proposed engineering‘structure–parameter–behavior–performance’serves to link core–shell structure,formulation parameters(e.g.,viscosity and surface tension),fluidic behavior(e.g.,shear thinning and Marangoni flow),and device performance(e.g.,resolution and photoluminescence efficiency).The findings provide theoretical support and decision-making guidance for the large-scale application and interdisciplinary expansion of QDIs.展开更多
The transports of the dynamic biochemical signals in the non-reversing pulsatile flows in the mixing microchannel of a Y-shaped microfluidic device are ana- lyzed. The results show that the mixing micro-channel acts a...The transports of the dynamic biochemical signals in the non-reversing pulsatile flows in the mixing microchannel of a Y-shaped microfluidic device are ana- lyzed. The results show that the mixing micro-channel acts as a low-pass filter, and the biochemical signals are nonlinearly modulated by the pulsatile flows, which depend on the biochemical signal frequency, the flow signal frequency, and the biochemical signal transporting distance. It is concluded that, the transfer characteristics of the dynamic biochemical signals, which are transported in the time-varying flows, should be carefully considered for better loading biochemical signals on the cells cultured on the bottom of the microfluidic channel.展开更多
This paper presents an analysis of dispersion of dynamic biochemical signals in steady flow in a shallow Y-type microfluidic channel. A method is presented to control the flow widths of two steady flows in the Y-type ...This paper presents an analysis of dispersion of dynamic biochemical signals in steady flow in a shallow Y-type microfluidic channel. A method is presented to control the flow widths of two steady flows in the Y-type microchannel from two inlets.The transfer function for the Y-type microchannel is given by solving the governing equation for the Taylor-Aris dispersion in the microchannel. The amplitude-frequency and phase-frequency relations are provided which show that a shallow Y-type microchannel acts as a low-pass filter. The transports of different dynamic biochemical signals are investigated. In comparison with a fully mixing microfluidic channel, the magnitudes of the dynamic signals at the outlets in a Y-type microchannel are much smaller than those in a fully mixing microchannel, which demonstrates that the amplitude attenuation in a Y-type microchannel is larger than that of a fully mixing microchannel due to the transverse molecular diffusion. In order to control the desired signal in a microchannel, the solution of the inverse problem for the channel is also presented.展开更多
When characterizing flows in miniaturized channels, the determination of the dynamic contact angle is important. By measuring the dynamic contact angle, the flow properties of the flowing liquid and the effect of mate...When characterizing flows in miniaturized channels, the determination of the dynamic contact angle is important. By measuring the dynamic contact angle, the flow properties of the flowing liquid and the effect of material properties on the flow can be characterized. A machine vision based system to measure the contact angle of front or rear menisci of a moving liquid plug is described in this article. In this research, transparent flow channels fabricated on thermoplastic polymer and sealed with an adhesive tape are used. The transparency of the channels enables image based monitoring and measurement of flow variables, including the dynamic contact angle. It is shown that the dynamic angle can be measured from a liquid flow in a channel using the image based measurement system. An image processing algorithm has been developed in a MATLAB environment. Images are taken using a CCD camera and the channels are illuminated using a custom made ring light. Two fitting methods, a circle and two parabolas, are experimented and the results are compared in the measurement of the dynamic contact angles.展开更多
The dry gas seal（DGS） has been widely used in high parameters centrifugal compressor, but the intense vibrations of shafting, especially in high-speed condition, usually result in DGS＇s failure. So the DGS＇s abili...The dry gas seal（DGS） has been widely used in high parameters centrifugal compressor, but the intense vibrations of shafting, especially in high-speed condition, usually result in DGS＇s failure. So the DGS＇s ability of resisting outside interference has become a determining factor of the further development of centrifugal compressor. However, the systematic researches of which about gas film disturbance characteristics of high parameters DGS are very little. In order to study gas film disturbance characteristics of high-speed and high-pressure spiral groove dry gas seal（S-DGS） with a flexibly mounted stator, rotor axial runout and misalignment are taken into consideration, and the finite difference method and analytical method are used to analyze the influence of gas film thickness disturbance on sealing performance parameters, what＇s more, the effects of many key factors on gas film thickness disturbance are systematically investigated. The results show that, when sealed pressure is 10.1MPa and seal face average linear velocity is 107.3 m/s, gas film thickness disturbance has a significant effect on leakage rate, but has relatively litter effect on open force; Excessively large excitation amplitude or excessively high excitation frequency can lead to severe gas film thickness disturbance; And it is beneficial to assure a smaller gas film thickness disturbance when the stator material density is between 3.1 g/cm3 to 8.4 g/cm3; Ensuring sealing performance while minimizing support axial stiffness and support axial damping can help to improve dynamic tracking property of dry gas seal. The proposed research provides the instruction to optimize dynamic tracking property of the DGS.展开更多
This paper puts forward using high-pressure water jet technology to control rock burst in roadway, and analyzes the theory of controlling rock burst in roadway by the weak structure zone model. The weak structure zone...This paper puts forward using high-pressure water jet technology to control rock burst in roadway, and analyzes the theory of controlling rock burst in roadway by the weak structure zone model. The weak structure zone is formed by using high-pressure water jet to cut the coal wall in a continuous and rotational way. In order to study the influence law of weak structure zone in surrounding rock, this paper numerically analyzed the influence law of weak structure zone, and the disturbance law of coal wall and floor under dynamic and static combined load. The results show that when the distance between high-pressure water jet drillings is 3 m and the diameter of drilling is 300 mm, continuous stress superposition zone can be formed. The weak structure zone can transfer and reduce the concentrated static load in surrounding rock, and then form distressed zone. The longer the high-pressure water jet drilling is, the larger the distressed zone is. The stress change and displacement change of non-distressed zone in coal wall and floor are significantly greater than that of distressed zone under dynamic and static combined load. And it shows that the distressed zone can effectively control rock burst in roadway under dynamic and static combined load. High-pressure water jet technology was applied in the haulage gate of 250203 working face in Yanbei Coal Mine, and had gained good effect. The study conclusions provide theoretical foundation and a new guidance for controlling rock burst in roadway.展开更多
In this study,based on the Luo bubble coalescence model,a model correction factor C_e for pressures according to the literature experimental results was introduced in the bubble coalescence efficiency term.Then,a coup...In this study,based on the Luo bubble coalescence model,a model correction factor C_e for pressures according to the literature experimental results was introduced in the bubble coalescence efficiency term.Then,a coupled modified population balance model(PBM) with computational fluid dynamics(CFD) was used to simulate a high-pressure bubble column.The simulation results with and without C_e were compared with the experimental data.The modified CFD-PBM coupled model was used to investigate its applicability to broader experimental conditions.These results showed that the modified CFD-PBM coupled model can predict the hydrodynamic behaviors under various operating conditions.展开更多
The bubble formation dynamics and size manipulation in the slurry of polystyrene microspheres in the microfluidic T-junction were visually investigated by a high-speed camera.Based on the evolution of the bubble neck ...The bubble formation dynamics and size manipulation in the slurry of polystyrene microspheres in the microfluidic T-junction were visually investigated by a high-speed camera.Based on the evolution of the bubble neck with time,the formation process of bubbles is divided into three stages:filling,squeezing and pinch-off.The particle concentration has an obvious effect on the squeezing stage,while less impact on the filling and pinch-off stages.In the squeezing stage,the evolution of the dimensionless minimum neck width of bubbles with time could be described by a power-law relationship.The increase of the particle concentration or continuous phase flow rate could lead to the increase of body flow of the continuous phase and the enhancement of the squeezing force acted on the bubble neck,correspondingly,the power-law index a in the squeezing stage enlarges.Moreover,the bubble size increases with the increase of the gas phase flow rate and the decrease of the particle concentration and continuous phase flow rate.However,the effect of the particle concentration on the bubble size weakens with the increase of the continuous phase flow rate.In addition,a new prediction correlation of the bubble size for the slurry system in a T-shape microchannel was proposed with good prediction accuracy.展开更多
This work applied molecular dynamics(MD)simulation to calculate densities of natural gas mixtures at extremely high pressure(>138 MPa)and high temperature(>200℃)conditions(x HPHT)to bridge the knowledge and tec...This work applied molecular dynamics(MD)simulation to calculate densities of natural gas mixtures at extremely high pressure(>138 MPa)and high temperature(>200℃)conditions(x HPHT)to bridge the knowledge and technical gaps between experiments and classical theories.The experimental data are scarce at these conditions which are also out of assumptions for classical predictive correlations,such as the Dranchuk&Abou-Kassem(DAK)equation of state(EOS).Force fields of natural gas components were carefully chosen from literatures and the simulation results are validated with experimental data.The largest relative error is 2.67%for pure hydrocarbons,2.99%for C1/C3 mixture,7.85%for C1/C4 mixture,and 8.47%for pure H2S.These satisfactory predictions demonstrate that the MD simulation approach is reliable to predict natural-and acid-gases thermodynamic properties.The validated model is further used to generate data for the study of the EOS with pressure up to 276 MPa and temperature up to 573 K.Our results also reveal that the Dranchuk&Abou-Kassem(DAK)EOS is capable of predicting natural gas compressibility to a satisfactory accuracy at x HPHT conditions,which extends the confidence range of the DAK EOS.展开更多
Hydraulic cylinder is a primary component of the hydraulic valve systems.The numerical study of hydraulic cylinder to evaluate the stress analysis,the life assessment and the performance of operation characteristics i...Hydraulic cylinder is a primary component of the hydraulic valve systems.The numerical study of hydraulic cylinder to evaluate the stress analysis,the life assessment and the performance of operation characteristics in hydraulic cylinder were described.The calculation of safety factor,fatigue life,piston chamber pressure,rod chamber pressure and the change of velocity of piston with flow time after the beginning of hydraulic cylinder were incorporated.Numerical analysis was performed using the commercial CFD code,ANSYS with unsteady,dynamic mesh model,two-way FSI(fluid-structure interaction)method and k-εturbulent model.The internal pressure in hydraulic cylinder through stress analysis show higher than those of the yield strength.展开更多
Single cell trapping in vitro by microfluidic device is an emerging approach for the study of the relationship between single cells and their dynamic biochemical microenvironments. In this paper, a hydrodynamic-based ...Single cell trapping in vitro by microfluidic device is an emerging approach for the study of the relationship between single cells and their dynamic biochemical microenvironments. In this paper, a hydrodynamic-based microfluidic device for single cell trapping is designed using a combination of stagnation point flow and physical barrier.The microfluidic device overcomes the weakness of the traditional ones, which have been only based upon either stagnation point flows or physical barriers, and can conveniently load dynamic biochemical signals to the trapped cell. In addition, it can connect with a programmable syringe pump and a microscope to constitute an integrated experimental system.It is experimentally verified that the microfluidic system can trap single cells in vitro even under flow disturbance and conveniently load biochemical signals to the trapped cell. The designed micro-device would provide a simple yet effective experimental platform for further study of the interactions between single cells and their microenvironments.展开更多
Concentration gradient and fluid shear stress(FSS)for cell microenvironment were investigated through microfluidic technology.The Darcy–Weisbach equation combined with computational fluid dynamics modeling was exploi...Concentration gradient and fluid shear stress(FSS)for cell microenvironment were investigated through microfluidic technology.The Darcy–Weisbach equation combined with computational fluid dynamics modeling was exploited to design the microfluidic chip,and the FSS distribution on the cell model with varying micro-channels(triangular,conical,and elliptical).The diffusion with the incompressible laminar flow model by solving the time-dependent diffusion–convection equation was applied to simulate the gradient profiles of concentration in the micro-channels.For the study of single cell in-depth,the FSS was investigated by the usage of polystyrene particles and the concentration diffusion distribution was studied by the usage of different colors of dyes.A successful agreement between model simulations and experimental data was obtained.Finally,based on the established method,the communication between individual cells was envisaged and modeled.The developed method provides valuable insights and allows to continuously improve the design of microfluidic devices for the study of single cell,the occurrence and development of tumors,and therapeutic applications.展开更多
The cellular response to the complex extracellular microenvironment is highly dynamic in time and type of extracellular matrix.Accurately reconstructing this process and analyzing the changes in receptor conformation ...The cellular response to the complex extracellular microenvironment is highly dynamic in time and type of extracellular matrix.Accurately reconstructing this process and analyzing the changes in receptor conformation on the cell membrane surface and intracellular or intercellular signaling has been a major challenge in analytical chemistry and biophysical methodology.In this paper,a time-coded multiconcentration microfluidic chemical waveform generator was developed for the dynamic signaling probing with single-cell array of high temporal resolution,high throughput,and multi-concentration combination stimulation.Based on innovative microchannel structure,sophisticated external control methods and multiplexing technology,the system not only allowed for temporally sequential permutations of the four concentrations of stimuli(time code),but also generated pulsed and continuous waveforms at different frequencies in a highly controllable manner.Furthermore,the single-cell trap array was set up to efficiently capture cells in suspension,dramatically increasing throughput and reducing experiment preparation time.The maximum frequency of the platform was 1 Hz,and one cell could be stimulated at multiple frequencies.To show the ability of the system to investigate rapid biochemical events in high throughput,pulse stimulation and continuous stimulation of different frequencies and different time codes,combined with four concentrations of histamine(HA),were generated for probing G protein-coupled receptor(GPCR)signaling in He La cells.Then,statistical analysis was performed for the mean peak height and mean peak area of the cellular response.We believe that the time-coded multi-concentration microfluidic chemical waveform generator will provide a novel strategy for analytical chemistry,biophysics,cell signaling,and individualized medicine applications.展开更多
基金Supported by the National Natural Science Foundation of China(50604019)the Innovation Team Foundation of China(50621403)
文摘Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied through theoretical analysis,experimentand field measurement.The results show that high-pressure pulsed water jet has threedynamic properties.What's more,the three dynamic effects can be found in low-permeabilitycoal seams.A new pulsed water jet with 200-1 000 Hz oscillation frequency andpeak pressure 2.5 times than average pressure was introduced.During bubble collapsing,sound vibration and instantaneous high pressures over 100 MPa enhanced the cuttingability of the high-pressure jet.Through high-pressure pulsed water jet drilling and slotting,the exposure area of coal bodies was greatly enlarged and pressure of the coal seamsrapidly decreased.Therefore,the permeability of coal seams was improved and gas absorptionrate also decreased.Application results show that gas adsorption rate decreasedby 30%-40%and the penetrability coefficient increased 100 times.This proves that high-pressurepulsed water is more efficient than other conventional methods.
基金support from the National Natural Science Foundation of China(Grant Nos.51975175 and 52375329)the Projects of Natural Science Key Research of Anhui Province(2023AH051664).
文摘The Mg–Zn–Gd alloy with quasicrystal icosahedral phase was processed by high-pressure torsion (HPT). The effect of bimodal I-phase on the dynamic recrystallization was analyzed by transmission electron microscopy. The results showed that the block I-phase can stimulate obvious particle-stimulated nucleation and dynamic recrystallization (DRX) grains were preferentially formed after HPT for 5 turns, while the granular I-phase only promoted the generation of sub-grains. The orientation relationship was determined as twofold//[1210] and fivefold//(0002)_(Mg). Moreover, after HPT for 9 turns, the DRX grains induced by block I-phase appeared to grow up and coarsened. Compared with block I-phase, the grains induced by granular I-phase presented much smaller size and distributed more homogeneous due to the strong pinning effect.
基金The research work presented in this paper is financially supported by a grant(NJZZ18139)from the scientific research project of Universities in Inner Mongoliaa grant(2018BS05003)from the Natural Science Foundation of Inner Mongoliaa grant(2017QDL-B07)from Inner Mongolia University of Science and Technology Innovation Fund Project.
文摘To improve energy density,the transportation,storage,and operations of hydrogen,methane,and compressed air vehicles currently require high-pressure compression.High-pressure solenoid valve becomes the vital element to above system.In order to reduce leakage and aerodynamic force influence,a new type high-pressure solenoid valve was proposed.The simulation model which included electromagnetic model,aerodynamic force model was established by means of the nonlinear mathematic models.Using the software MATLAB/Simulink for simulation,the dynamic response characteristics of high-pressure pneumatic solenoid valve were obtained under different pulse width modulation(PWM)input control signals.Results show that,first of all,the new type of high-pressure solenoid valve can meet the switch requirement.Secondly,the opening movement and closing movement of the spool lags the PWM rising signal,and the coil current fluctuates significantly during the movement of the spool.Lastly,on/off status of high-pressure valve cannot be represented by the duty cycle.This research can be referred in the design of the high-pressure solenoid valve..
基金We acknowledge support from the equipment research and development projects of the Chinese Academy of Sciences,“On-chip integrated optical biochemical detection key technology research and development team,”E11YTB1001.
文摘In this work,an automated microfluidic chip that uses negative pressure to sample and analyze solutions with high temporal resolution was developed.The chip has a T-shaped channel for mixing the sample with a fluorescent indicator,a flow-focusing channel for generating droplets in oil,and a long storage channel for incubating and detecting the droplets.By monitoring the fluorescence intensity of the droplets,the device could detect changes in solution accurately over time.The chip can generate droplets at frequencies of up to 42 Hz with a mixing ratio of 1:1 and a temporal resolution of 3–6 s.It had excellent linearity in detecting fluorescein solution in the concentration range 1–5μM.This droplet microfluidic chip provides several advantages over traditional methods,including high temporal resolution,stable droplet generation,and faster flow rates.This approach could be applied to monitoring calcium ions with a dynamic range from 102 to 107 nM and a detection limit of 10 nM.
基金financially supported by the National Natural Science Foundation of China(No.2247030172)。
文摘Janus vesicles,unique nanostructures,have attracted significant attention for their diverse applications in biomedical and microfluidic systems.In practical micro-nano systems,flow and electric fields often coexist,and the perforation dynamics of Janus vesicles exhibit complex motion due to their synergistic effects.Studying Janus vesicle perforation dynamics under the combined influence of fluid flow and electric fields provides valuable insights into their applications in drug delivery,catalyst delivery,and controlled release.This study focuses on the perforation dynamics and directional motion of Janus vesicles in microchannels,emphasizing how electric field strength and charge distribution on the membrane influence vesicle migration,deformation,and trajectories.Results show that when electromagnetic forces and flow-driven forces align,increasing electric field strength promotes vesicle migration and perforation.Vesicle migration is correlated with charge distribution on the membrane,with broader distributions resulting in more pronounced migration.When electric field strength remains constant,charge distribution has little effect on vesicle deformation.Conversely,when electromagnetic forces and flow-driven forces oppose,increasing electric field strength inhibits vesicle migration.At a specific potential difference,charged vesicles cease movement before reaching the perforation site,indicating the critical potential for perforation.The study also reveals that the direction of the electric field significantly affects vesicle migration direction.Adjusting potential values at microchannel boundaries can control the directional movement of Janus vesicles.This research provides new insights into Janus vesicle behavior in complex environments and deepens understanding of their potential as drug carriers for delivery and targeted therapy.
基金the Natural Science Foundation of Shandong Province,China(No.ZR2021QE157).
文摘High-pressure water jet technology has emerged as a highly effective method for removing industrial-scale deposits from pipelines,offering a clean,efficient,and environmentally sustainable alternative to conventional mechanical or chemical cleaning techniques.Among the many parameters influencing its performance,the geometry of the nozzle plays a decisive role in governing jet coherence,impact pressure distribution,and overall cleaning efficiency.In this study,a comprehensive numerical and experimental investigation is conducted to elucidate the influence of nozzle geometry on the behavior of high-pressure water jets.Using Computational Fluid Dynamics(CFD)simulations based on the Volume of Fluid(VOF)approach,the jet dynamics and impingement characteristics of three representative nozzle configurations—flat,conical,and tapered—are systematically analyzed.Particular attention is devoted to the tapered nozzle,where variations in the outlet diameter are explored to determine their effect on flow structure,jet stability,and impact performance.The numerical predictions are rigorously validated against experimental measurements,demonstrating excellent quantitative agreement and confirming the robustness of the computational model.Results show that the tapered nozzle,characterized by its elongated conical transition section,promotes a more stable jet core and superior efflux performance compared to flat and conical geometries.Furthermore,the exit diameter is found to exert a profound influence on jet development.At an inlet pressure of 130 MPa,increasing the tapered nozzle's outlet diameter from 0.8 mm to 1.2 mm enlarges the coherent core region,enhances jet stability,and improves hydraulic energy utilization.Under these conditions,the total impact pressure on the target surface increases by 33.14%,while the overall cleaning efficiency improves by 40.44%.
基金supported by the Shenzhen Polytechnic Research Fund(6023310025K)Post-doctoral Later-stage Foundation Project of Shenzhen Polytechnic(6023271017K)Horizontal Technology Development Project(6024260101K).
文摘Quantumdot inks(QDIs)represent an emerging functionalmaterial that integrates nanotechnology and fluid engineering,demonstrating significant application potential in flexible optoelectronics and high-color gamut displays.Their wide applicability is due to a unique quantum confinement effect that enables precise spectral tunability and solution-processable properties.However,the complex fluid dynamics associated with QDIs at micro-/nano-scales severely limit the accuracy of inkjet printing and pattern deposition.This review systematically addresses recent advances in the hydrodynamics of QDIs,establishing scientific mechanisms and key technical breakthroughs from an interdisciplinary perspective.Current research has focused on three optimization directions:(1)regulating ligand structures to enhance colloidal stability,flow consistency,and anti-shear performance while mitigating nanoparticle aggregation;(2)incorporating low-viscosity or high-volatility solvents and surface tension modifiers to modify droplet dynamic characteristics and suppress the“coffee-ring”effect;(3)integrating advanced technologies such as electrohydrodynamic jetting and microfluidic targeted deposition to achieve submicron pattern resolution and high film uniformity,expanding adaptability in flexible electronics,biosensing,and anti-counterfeiting printing.A comparison of current technical routes and critical performance indicators has identified the dominant variables that influence QDI macroscopic/microscopic properties.A comprehensive analytical framework is presented which spans material structure,rheological behavior,manufacturing processes,and functional characteristics.Moreover,a proposed engineering‘structure–parameter–behavior–performance’serves to link core–shell structure,formulation parameters(e.g.,viscosity and surface tension),fluidic behavior(e.g.,shear thinning and Marangoni flow),and device performance(e.g.,resolution and photoluminescence efficiency).The findings provide theoretical support and decision-making guidance for the large-scale application and interdisciplinary expansion of QDIs.
基金Project supported by the National Natural Science Foundation of China(Nos.11172060 and11672065)
文摘The transports of the dynamic biochemical signals in the non-reversing pulsatile flows in the mixing microchannel of a Y-shaped microfluidic device are ana- lyzed. The results show that the mixing micro-channel acts as a low-pass filter, and the biochemical signals are nonlinearly modulated by the pulsatile flows, which depend on the biochemical signal frequency, the flow signal frequency, and the biochemical signal transporting distance. It is concluded that, the transfer characteristics of the dynamic biochemical signals, which are transported in the time-varying flows, should be carefully considered for better loading biochemical signals on the cells cultured on the bottom of the microfluidic channel.
基金National Natural Science Foundation of Chinagrant number:11172060the Fundamental Research Funds for the Central Universities in China
文摘This paper presents an analysis of dispersion of dynamic biochemical signals in steady flow in a shallow Y-type microfluidic channel. A method is presented to control the flow widths of two steady flows in the Y-type microchannel from two inlets.The transfer function for the Y-type microchannel is given by solving the governing equation for the Taylor-Aris dispersion in the microchannel. The amplitude-frequency and phase-frequency relations are provided which show that a shallow Y-type microchannel acts as a low-pass filter. The transports of different dynamic biochemical signals are investigated. In comparison with a fully mixing microfluidic channel, the magnitudes of the dynamic signals at the outlets in a Y-type microchannel are much smaller than those in a fully mixing microchannel, which demonstrates that the amplitude attenuation in a Y-type microchannel is larger than that of a fully mixing microchannel due to the transverse molecular diffusion. In order to control the desired signal in a microchannel, the solution of the inverse problem for the channel is also presented.
基金This research was done as part of TEKES-funded PanFlow project and as part of a project OPTIMI funded by the Academy of Finland (grant number 117587) in Micro- and Nanosystems Research Group, Tampere University of Technology, Finland.
文摘When characterizing flows in miniaturized channels, the determination of the dynamic contact angle is important. By measuring the dynamic contact angle, the flow properties of the flowing liquid and the effect of material properties on the flow can be characterized. A machine vision based system to measure the contact angle of front or rear menisci of a moving liquid plug is described in this article. In this research, transparent flow channels fabricated on thermoplastic polymer and sealed with an adhesive tape are used. The transparency of the channels enables image based monitoring and measurement of flow variables, including the dynamic contact angle. It is shown that the dynamic angle can be measured from a liquid flow in a channel using the image based measurement system. An image processing algorithm has been developed in a MATLAB environment. Images are taken using a CCD camera and the channels are illuminated using a custom made ring light. Two fitting methods, a circle and two parabolas, are experimented and the results are compared in the measurement of the dynamic contact angles.
基金Supported by National Natural Science Foundation of China(Grant No.51575490)National Key Basic Research Program of China(973 Program,Grant No.2014CB046404)Natural Science Key Foundation of Zhejiang Province,China(Grant No.LZ15E050002)
文摘The dry gas seal（DGS） has been widely used in high parameters centrifugal compressor, but the intense vibrations of shafting, especially in high-speed condition, usually result in DGS＇s failure. So the DGS＇s ability of resisting outside interference has become a determining factor of the further development of centrifugal compressor. However, the systematic researches of which about gas film disturbance characteristics of high parameters DGS are very little. In order to study gas film disturbance characteristics of high-speed and high-pressure spiral groove dry gas seal（S-DGS） with a flexibly mounted stator, rotor axial runout and misalignment are taken into consideration, and the finite difference method and analytical method are used to analyze the influence of gas film thickness disturbance on sealing performance parameters, what＇s more, the effects of many key factors on gas film thickness disturbance are systematically investigated. The results show that, when sealed pressure is 10.1MPa and seal face average linear velocity is 107.3 m/s, gas film thickness disturbance has a significant effect on leakage rate, but has relatively litter effect on open force; Excessively large excitation amplitude or excessively high excitation frequency can lead to severe gas film thickness disturbance; And it is beneficial to assure a smaller gas film thickness disturbance when the stator material density is between 3.1 g/cm3 to 8.4 g/cm3; Ensuring sealing performance while minimizing support axial stiffness and support axial damping can help to improve dynamic tracking property of dry gas seal. The proposed research provides the instruction to optimize dynamic tracking property of the DGS.
基金supported by the National Natural Science Foundation of China (Nos. 51574243, 51404269)the Fundamental Research Funds for the Central Universities of China (No. 2014XT01)+1 种基金Guizhou Science and Technology Foundation of China (No. 20152072)the Priority Academic Program Development of Jiangsu Higher Education Institutions, China (No. SZBF2011-6B35)
文摘This paper puts forward using high-pressure water jet technology to control rock burst in roadway, and analyzes the theory of controlling rock burst in roadway by the weak structure zone model. The weak structure zone is formed by using high-pressure water jet to cut the coal wall in a continuous and rotational way. In order to study the influence law of weak structure zone in surrounding rock, this paper numerically analyzed the influence law of weak structure zone, and the disturbance law of coal wall and floor under dynamic and static combined load. The results show that when the distance between high-pressure water jet drillings is 3 m and the diameter of drilling is 300 mm, continuous stress superposition zone can be formed. The weak structure zone can transfer and reduce the concentrated static load in surrounding rock, and then form distressed zone. The longer the high-pressure water jet drilling is, the larger the distressed zone is. The stress change and displacement change of non-distressed zone in coal wall and floor are significantly greater than that of distressed zone under dynamic and static combined load. And it shows that the distressed zone can effectively control rock burst in roadway under dynamic and static combined load. High-pressure water jet technology was applied in the haulage gate of 250203 working face in Yanbei Coal Mine, and had gained good effect. The study conclusions provide theoretical foundation and a new guidance for controlling rock burst in roadway.
基金Supported by the National Natural Science Foundation of China(91634101)The Project of Construction of Innovative TeamsTeacher Career Development for Universities and Colleges under Beijing Municipality(IDHT20180508)
文摘In this study,based on the Luo bubble coalescence model,a model correction factor C_e for pressures according to the literature experimental results was introduced in the bubble coalescence efficiency term.Then,a coupled modified population balance model(PBM) with computational fluid dynamics(CFD) was used to simulate a high-pressure bubble column.The simulation results with and without C_e were compared with the experimental data.The modified CFD-PBM coupled model was used to investigate its applicability to broader experimental conditions.These results showed that the modified CFD-PBM coupled model can predict the hydrodynamic behaviors under various operating conditions.
基金supported by the National Natural Science Foundation of China(21978197 and 21776200)。
文摘The bubble formation dynamics and size manipulation in the slurry of polystyrene microspheres in the microfluidic T-junction were visually investigated by a high-speed camera.Based on the evolution of the bubble neck with time,the formation process of bubbles is divided into three stages:filling,squeezing and pinch-off.The particle concentration has an obvious effect on the squeezing stage,while less impact on the filling and pinch-off stages.In the squeezing stage,the evolution of the dimensionless minimum neck width of bubbles with time could be described by a power-law relationship.The increase of the particle concentration or continuous phase flow rate could lead to the increase of body flow of the continuous phase and the enhancement of the squeezing force acted on the bubble neck,correspondingly,the power-law index a in the squeezing stage enlarges.Moreover,the bubble size increases with the increase of the gas phase flow rate and the decrease of the particle concentration and continuous phase flow rate.However,the effect of the particle concentration on the bubble size weakens with the increase of the continuous phase flow rate.In addition,a new prediction correlation of the bubble size for the slurry system in a T-shape microchannel was proposed with good prediction accuracy.
基金partial financial support from Ballard Petroleum Holdings and Yangtze Universitythe Schooner Supercomputing from the University of Oklahomathe startup support from the University of Oklahoma。
文摘This work applied molecular dynamics(MD)simulation to calculate densities of natural gas mixtures at extremely high pressure(>138 MPa)and high temperature(>200℃)conditions(x HPHT)to bridge the knowledge and technical gaps between experiments and classical theories.The experimental data are scarce at these conditions which are also out of assumptions for classical predictive correlations,such as the Dranchuk&Abou-Kassem(DAK)equation of state(EOS).Force fields of natural gas components were carefully chosen from literatures and the simulation results are validated with experimental data.The largest relative error is 2.67%for pure hydrocarbons,2.99%for C1/C3 mixture,7.85%for C1/C4 mixture,and 8.47%for pure H2S.These satisfactory predictions demonstrate that the MD simulation approach is reliable to predict natural-and acid-gases thermodynamic properties.The validated model is further used to generate data for the study of the EOS with pressure up to 276 MPa and temperature up to 573 K.Our results also reveal that the Dranchuk&Abou-Kassem(DAK)EOS is capable of predicting natural gas compressibility to a satisfactory accuracy at x HPHT conditions,which extends the confidence range of the DAK EOS.
基金supported by the International Cooperation on Technology Development Program of the Korea Institute for Advancement of Technology ( KIAT),Republic of Korea ( N0000902)
文摘Hydraulic cylinder is a primary component of the hydraulic valve systems.The numerical study of hydraulic cylinder to evaluate the stress analysis,the life assessment and the performance of operation characteristics in hydraulic cylinder were described.The calculation of safety factor,fatigue life,piston chamber pressure,rod chamber pressure and the change of velocity of piston with flow time after the beginning of hydraulic cylinder were incorporated.Numerical analysis was performed using the commercial CFD code,ANSYS with unsteady,dynamic mesh model,two-way FSI(fluid-structure interaction)method and k-εturbulent model.The internal pressure in hydraulic cylinder through stress analysis show higher than those of the yield strength.
基金supported by the National Natural Science Foundation of China (Grants 11172060 and 31370948)
文摘Single cell trapping in vitro by microfluidic device is an emerging approach for the study of the relationship between single cells and their dynamic biochemical microenvironments. In this paper, a hydrodynamic-based microfluidic device for single cell trapping is designed using a combination of stagnation point flow and physical barrier.The microfluidic device overcomes the weakness of the traditional ones, which have been only based upon either stagnation point flows or physical barriers, and can conveniently load dynamic biochemical signals to the trapped cell. In addition, it can connect with a programmable syringe pump and a microscope to constitute an integrated experimental system.It is experimentally verified that the microfluidic system can trap single cells in vitro even under flow disturbance and conveniently load biochemical signals to the trapped cell. The designed micro-device would provide a simple yet effective experimental platform for further study of the interactions between single cells and their microenvironments.
基金National Natural Science Foundation of China(No.21804045)Fujian Provincial Department of Science and Technology(No.2019I0014)Promotion Program for Young and Middle-aged Teachers in Science and Technology Research of Huaqiao University(No.ZQN-PY612)。
文摘Concentration gradient and fluid shear stress(FSS)for cell microenvironment were investigated through microfluidic technology.The Darcy–Weisbach equation combined with computational fluid dynamics modeling was exploited to design the microfluidic chip,and the FSS distribution on the cell model with varying micro-channels(triangular,conical,and elliptical).The diffusion with the incompressible laminar flow model by solving the time-dependent diffusion–convection equation was applied to simulate the gradient profiles of concentration in the micro-channels.For the study of single cell in-depth,the FSS was investigated by the usage of polystyrene particles and the concentration diffusion distribution was studied by the usage of different colors of dyes.A successful agreement between model simulations and experimental data was obtained.Finally,based on the established method,the communication between individual cells was envisaged and modeled.The developed method provides valuable insights and allows to continuously improve the design of microfluidic devices for the study of single cell,the occurrence and development of tumors,and therapeutic applications.
基金the National Natural Science Foundation of China(Nos.22074047,21775049 and 31700746)the Hubei Provincial Natural Science Foundation of China(No.2020CFB578)the Fundamental Research Funds for Central Universities,HUST(Nos.2020kfy XJJS034 and 2021GCRC056)。
文摘The cellular response to the complex extracellular microenvironment is highly dynamic in time and type of extracellular matrix.Accurately reconstructing this process and analyzing the changes in receptor conformation on the cell membrane surface and intracellular or intercellular signaling has been a major challenge in analytical chemistry and biophysical methodology.In this paper,a time-coded multiconcentration microfluidic chemical waveform generator was developed for the dynamic signaling probing with single-cell array of high temporal resolution,high throughput,and multi-concentration combination stimulation.Based on innovative microchannel structure,sophisticated external control methods and multiplexing technology,the system not only allowed for temporally sequential permutations of the four concentrations of stimuli(time code),but also generated pulsed and continuous waveforms at different frequencies in a highly controllable manner.Furthermore,the single-cell trap array was set up to efficiently capture cells in suspension,dramatically increasing throughput and reducing experiment preparation time.The maximum frequency of the platform was 1 Hz,and one cell could be stimulated at multiple frequencies.To show the ability of the system to investigate rapid biochemical events in high throughput,pulse stimulation and continuous stimulation of different frequencies and different time codes,combined with four concentrations of histamine(HA),were generated for probing G protein-coupled receptor(GPCR)signaling in He La cells.Then,statistical analysis was performed for the mean peak height and mean peak area of the cellular response.We believe that the time-coded multi-concentration microfluidic chemical waveform generator will provide a novel strategy for analytical chemistry,biophysics,cell signaling,and individualized medicine applications.
