Gypsum rocks are highly susceptible to mechanical deterioration under the coupled effects of wet-dry(W-D)cycles and flow rates,which significantly influence the stability of underground excavations.Despite extensive r...Gypsum rocks are highly susceptible to mechanical deterioration under the coupled effects of wet-dry(W-D)cycles and flow rates,which significantly influence the stability of underground excavations.Despite extensive research on the effects of W-D cycles,the coupling influence of flow rates and W-D cycles on gypsum rocks remains poorly understood.This study investigates the mechanical behavior and deterioration mechanisms of gypsum rocks subjected to varying W-D cycles and flow rate conditions.Axial compression tests,along with nuclear magnetic resonance(NMR)techniques,were employed to analyze the stress-strain response and microstructural changes.Based on the disturbed state concept(DSC)theory,a W-D deterioration model and a DSC-based constitutive model were developed to describe the degradation trends and mechanical responses of gypsum rocks under different conditions.The results demonstrate that key mechanical indices,elastic modulus,cohesion,uniaxial compressive strength(UCS),and internal friction angle,exhibit logarithmic declines with increasing W-D cycles,with higher flow rates accelerating the deterioration process.The theoretical models accurately capture the nonlinear compaction behavior,peak stress,and post-peak response of gypsum specimens.This study provides valuable insights for predicting the mechanical behavior of gypsum rocks and improving the stability assessments of underground structures under complex environmental conditions.展开更多
Rational allocation of water flow energy in river networks is essential to addressing water-related issues in river network areas.However,current methods of calculating the spatiotemporal distribution of flow energy i...Rational allocation of water flow energy in river networks is essential to addressing water-related issues in river network areas.However,current methods of calculating the spatiotemporal distribution of flow energy in river networks lack precision and efficiency.This paper introduces a novel hydrodynamic representation,the energy flow rate,defined as the product of the flow rate and kinetic energy head,to quantify the kinetic energy stored and transported in river networks.A linear equation system for the energy flow rate in a river network has been theoretically derived,enabling rapid calculations under steady flow conditions.A simplified equation is proposed to describe the exponential decay of the energy flow rate,accompanied by potential energy conversion.The coefficients in the linear equation system are determined using control equations at flow confluence and diversion nodes.This study provides foundational insights that can be used to develop new hydrodynamic modeling strategies to regulate water flow energy and achieve coordinated management of water-related issues in river networks.展开更多
The two-fluid model coupled with population balance model was used for simulating the gas-liquid flow in the Ruhrstahl-Heraeus(RH)degasser.The predicted circulation flow rate was compared with that measured from a wat...The two-fluid model coupled with population balance model was used for simulating the gas-liquid flow in the Ruhrstahl-Heraeus(RH)degasser.The predicted circulation flow rate was compared with that measured from a water model experiment to validate the mathematical model.Then,influence of snorkel immersion depth on liquid circulation flow rate was numerically investigated under an atmospheric pressure of 101 and 84 kPa,respectively.Predicted result indicates that the circulation flow rate of the RH degasser in the high-altitude area was severely reduced because of the decrease in atmospheric pressure.However,increasing the snorkel immersion depth from 0.5 to 0.7 m can compensate for the decrease in atmospheric pressure.Industrial test result indicates that decarburization rate is significantly enhanced by increasing the snorkel immersion depth.Through optimization,the percentage of heats with a final carbon content less than 0.002 wt.%is significantly increased from 22.0%to 96.4%.展开更多
Geothermal energy has gained wide attention as a renewable alternative for mitigating greenhouse gas emissions.The advancements in enhanced geothermal system technology have enabled the exploitation of previously inac...Geothermal energy has gained wide attention as a renewable alternative for mitigating greenhouse gas emissions.The advancements in enhanced geothermal system technology have enabled the exploitation of previously inaccessible geothermal resources.However,the extraction of geothermal energy from deep reservoirs poses many challenges due to high‐temperature and high‐geostress conditions.These factors can significantly impact the surrounding rock and its fracture formation.A comprehensive understanding of the thermal–hydraulic–mechanical(THM)coupling effect is crucial to the safe and efficient exploitation of geothermal resources.This study presented a THM coupling numerical model for the geothermal reservoir of the Yangbajing geothermal system.This proposed model investigated the geothermal exploitation performance and the stress distribution within the reservoir under various combinations of geothermal wells and mass flow rates.The geothermal system performance was evaluated by the criteria of outlet temperature and geothermal productivity.The results indicate that the longer distance between wells can increase the outlet temperature of production wells and improve extraction efficiency in the short term.In contrast,the shorter distance between wells can reduce the heat exchange area and thus mitigate the impact on the reservoir stress.A larger mass flow rate is conducive to the production capacity enhancement of the geothermal system and,in turn causes a wider range of stress disturbance.These findings provide valuable insights into the optimization of geothermal energy extraction while considering reservoir safety and long‐term sustainability.This study deepens the understanding of the THM coupling effects in geothermal systems and provides an efficient and environmentally friendly strategy for a geothermal energy system.展开更多
Offset-tracking is an essential method for deriving glacier flow rates using optical imagery.Sentinel-2(S2)and Landsat-8/9(L8/9)are popular optical satellites or constellations for polar studies,offering high spatial ...Offset-tracking is an essential method for deriving glacier flow rates using optical imagery.Sentinel-2(S2)and Landsat-8/9(L8/9)are popular optical satellites or constellations for polar studies,offering high spatial resolution with relatively short revisit time,wide swath width,and free accessibility.To evaluate and compare the precision of offset-tracking results yielded with these two kinds of data,in this study S2 and L8/9 imagery observed in Petermann Glacier in Greenland,Karakoram in High-Mountains Asia,and Amery Ice Shelf in the Antarctic are analyzed.Outliers and various systematic error sources in the offset-tracking results including orbital and strip errors were analyzed and eliminated at the pre-process stage.Precision at the off-glacier(bare rock)region was evaluated by presuming that no deformation occurred;then for both glacierized and the off-glacier regions,precision of velocity time series was evaluated based on error propagation theory.The least squares method based on connected components was used to solve flow rates time series based on multi-pair images offset-tracking.The results indicated that S2 achieved slightly higher precision than L8/9 in terms of both single-pair derived displacements and least square solved daily flow rates time series.Generally,the RMSE of daily velocity is 26%lower for S2 than L8/9.Moreover,S2 provided higher temporal resolution for monitoring glacier flow rates.展开更多
Developing a novel drop counter by introducing the Internet of Things concept has been vigorously conducted in recent years. Understanding the newly introduced drop counter’s flow rate control accuracy and flow rate ...Developing a novel drop counter by introducing the Internet of Things concept has been vigorously conducted in recent years. Understanding the newly introduced drop counter’s flow rate control accuracy and flow rate count feature is essential for improving safety in infusion management. This study aimed to verify if the new drop counters could secure accurate flow rate and drip count by conducting actual flow rate measurements using gravimetry and functional evaluation. A drop counter was attached to each drip chamber of the infusion set, and an IV drip was conducted at the 100 ml/h flow rate. The weight of discharged physiological saline was measured to plot trumpet curves. Next, three different types of drop counters were evaluated to determine if they maintained drip count accuracy according to the changes in their position angles. The flow rate errors in all conditions indicated trumpet-like curves, exhibiting an overall error range within ±10% in all observation windows. Although every drop counter successfully detected and measured dripping, it was challenging in some counters to detect dripping when the drip chamber was tilted. In comparing adult and pediatric IV sets, the adult IV set was found to be less likely to detect dripping in the angled position. No significant differences in results were confirmed between high and low flow rates, suggesting that the drop count function would not be affected by the flow rate in the ranges of typical infusion practices. Doppler sensors have a wide range of measurements and high sensitivity;the dripping was detected successfully even when the drip chamber was tilted, probably due to the advantages of these sensors. In contrast, miscounts occurred in those equipped with infrared sensors, which could not detect light intensity changes in tilted positions. Understanding the tendencies in flow rate errors in infusion can be valuable information for infusion management.展开更多
Based on the similarity principles, a 1 ： 7 scale physical model was established to study the behavior of molten steel flow and inclusion removal in a 145 t Rheinsahl-Heraeus （RH） degasser. On the basis of the quan...Based on the similarity principles, a 1 ： 7 scale physical model was established to study the behavior of molten steel flow and inclusion removal in a 145 t Rheinsahl-Heraeus （RH） degasser. On the basis of the quantitative measurements of the circulation flow rate and inclusion removal under various lifting gas flow rates, the effect of circulation flow rate on inclusion removal was investigated in the RH degasser. The inclusion removal rate shows the trend of first increase and then decrease twice with increasing the circulation flow rate when the circulation flow rates are smaller than 104.7 L/min. Whereas, the inclusion removal rate increases again with the further increase in circu- lation flow rate when the circulation flow rate is larger than 104.7 L/min. At lower circulation flow rates, inclusions are mainly removed by Stokes flotation to the slag/steel interface after inclusions are transferred near the slag/steel interface by the circulation flow. At higher circulation flow rates, the collision and aggregation of inclusions improves the inclusion removal efficiency. With the further increase in the circulation flow rate, inclusions are mainly removed by following the turbulent fluctuation （turbulent diffusion） to the slag/steel interface after inclusions are transferred near the slag/steel interface by the circulation flow.展开更多
The bleed hole diameter,depth,and boundary layer thickness are key design parameters of a supersonic bleed system.The evolution trend of single-hole bleed flow coefficient with the ratio of boundary layer thickness to...The bleed hole diameter,depth,and boundary layer thickness are key design parameters of a supersonic bleed system.The evolution trend of single-hole bleed flow coefficient with the ratio of boundary layer thickness to bleed hole diameter and the ratio of bleed hole depth to diameter is investigated by numerical simulations under choking and non-choking conditions.The results show that the subsonic leading edge of the circular hole and the subsonic part of the boundary layer are the main factors causing lateral flow of the bleed hole.The effect of diameter on bleed mass flow rate is due to the viscous effect which reduces the effective diameter.The larger the ratio of displacement thickness to bleed hole diameter,the more obvious the viscous effect is.The depth affects bleed flow rate by changing the opening and closing states of the separation zone.When a certain depth is reached,the development of the boundary layer reduces the effective captured stream tube and thus reduces the bleed mass flow rate.The main objective of the study is to obtain the physical mechanism of the bleed hole size parameters affecting the bleed mass flow rate,and to provide theoretical guidance for the selection of the size of bleed holes in the design of a porous arrays bleed system in hypersonic inlets.展开更多
Oil-air two-phase flow measurement was investigated with a Venturi and void fraction meters in this work. This paper proposes a new flow rate measurement correlation in which the effect of the velocity ratio between g...Oil-air two-phase flow measurement was investigated with a Venturi and void fraction meters in this work. This paper proposes a new flow rate measurement correlation in which the effect of the velocity ratio between gas and liquid was considered. With the pressure drop across the Venturi and the void fraction that was measured by electrical capacitance tomography apparatus, both mixture flow rate and oil flow rate could be obtained by the correlation. Experiments included bubble-, slug-, wave and annular flow with the void fraction ranging from 15% to 83%, the oil flow rate ranging from 0.97 kg/s to 1.78 kg/s, the gas flow rate ranging up to 0.018 kg/s and quality ranging nearly up to 2.0%. The root-mean-square errors of mixture mass flow rate and that of oil mass flow rate were less than 5%. Furthermore, coefficients of the correlation were modified based on flow regimes, with the results showing reduced root-mean-square errors.展开更多
For spacecraft working in vacuum environment, sublimator is an effective heat rejection approach to reject system's peak heat load, and supplement spacecraft radiation heat rejection. For a spacecraft active fluid...For spacecraft working in vacuum environment, sublimator is an effective heat rejection approach to reject system's peak heat load, and supplement spacecraft radiation heat rejection. For a spacecraft active fluid loop thermal control system combined with sublimator, waste heat generated from multi-point distributed heat sources could be collected by the fluid loop efficiently. However, the heat and mass transfer performances of the sublimator combined with fluid loop have not been adequately studied in previous research, especially for the influences of the heat load. Since work fluid mass flow rate is the main factor affecting heat load of the fluid loop, this context experimentally studied influences of the fluid loop mass flow rate on sublimator start-up transient characteristics, including heat transfer performances, response time, and work stability. Results indicated that the fluid loop mass flow rate affected the sublimator heat and mass transfer performances obviously, but the heat rejection ability is not always increase with the increasing of the fluid loop mass flow rate. In addition, we obtained the condition to judge whether there is a positive correlation between heat rejection ability and fluid loop mass flow rate.展开更多
This paper discussed influences of flow rates of O_2, C_3H_8, and compressedair on the melting degree of particles during HVOF (high velocity oxy-fuel) sprayed CoCrW coating.The O_2 flow rate has the maximal effect on...This paper discussed influences of flow rates of O_2, C_3H_8, and compressedair on the melting degree of particles during HVOF (high velocity oxy-fuel) sprayed CoCrW coating.The O_2 flow rate has the maximal effect on the melting of particles, the C_3H_8 flow rate has thesecond, and the compressed air flow rate has the minimal effect. The bond strength of the HVOFsprayed CoCrW coating is over 54 MPa. The porosity ratio of the HVOF sprayed CoCrW coating afteroptimization of gas flow rates is less than 2%. The average microhardness of the coating is up toHV_(0.1) 545. The oxidation amount per unit area of the HVOF sprayed CoCrW coating increases withthe holding time increasing at 800℃. In the same way, the oxidation amount of the coating increasesas the temperature increases. Particularly, the oxidation of the coating drastically increases over850℃.展开更多
To investigate the effects of flow rate on phytoplankton dynamics and related environment variables,a set of enclosure experiments with different fl ow rates were conducted in an artificial lake. We monitored nutrient...To investigate the effects of flow rate on phytoplankton dynamics and related environment variables,a set of enclosure experiments with different fl ow rates were conducted in an artificial lake. We monitored nutrients,temperature,dissolved oxygen,p H,conductivity,turbidity,chlorophyll-a and phytoplankton levels. The lower biomass in all flowing enclosures showed that flow rate significantly inhibited the growth of phytoplankton. A critical flow rate occurred near 0.06 m/s,which was the lowest relative inhibitory rate. Changes in flow conditions affected algal competition for light,resulting in a dramatic shift in phytoplankton composition,from blue-green algae in still waters to green algae in flowing conditions. These findings indicate that critical flow rate can be useful in developing methods to reduce algal bloom occurrence. However,flow rate significantly enhanced the inter-relationships among environmental variables,in particular by inducing higher water turbidity and vegetative reproduction of periphyton( Spirogyra). These changes were accompanied by a decrease in underwater light intensity,which consequently inhibited the photosynthetic intensity of phytoplankton. These results warn that a universal critical flow rate might not exist,because the effect of flow rate on phytoplankton is interlinked with many other environmental variables.展开更多
Formation water invasion is the most troublesome problem associated with air drilling. However, it is not economical to apply mist drilling when only a small amount of water flows into wellbore from formation during a...Formation water invasion is the most troublesome problem associated with air drilling. However, it is not economical to apply mist drilling when only a small amount of water flows into wellbore from formation during air drilling. Formation water could be circulated out of the wellbore through increasing the gas injection rate. In this paper, the Angel model was modified by introducing Nikurade friction factor for the flow in coarse open holes and translating formation water rate into equivalent penetration rate. Thus the distribution of annular pressure and the relationship between minimum air injection rate and formation water rate were obtained. Real data verification indicated that the modified model is more accurate than the Angel model and can provide useful information for air drilling.展开更多
In this paper,Me （Me=Cr,Zr） and N co-doped diamond like carbon （DLC-MeN） composite films were prepared on cemented carbide substrates by pulsed bias arc ion plating.The effect of nitrogen flow rates on the microst...In this paper,Me （Me=Cr,Zr） and N co-doped diamond like carbon （DLC-MeN） composite films were prepared on cemented carbide substrates by pulsed bias arc ion plating.The effect of nitrogen flow rates on the microstructure and properties of the films were investigated by X-ray photoelectron spectroscopy （XPS）,Raman spectra,grazing incident X-ray diffraction （GIXRD）,high resolution transmission electron microscopy （HRTEM） and nano-indentation.Raman,GIXRD and HRTEM results show that the deposited films are nanocomposite films with MeN nanocrystalline phase embedded within DLC amorphous matrix,which are vital for the mechanical properties of the films.The nitrogen flow rate has significant effect on the compositions and structures and hence on the hardness and elastic modulus of the films,and increasing nitrogen flow rate decreases drastically the hardness and elastic modulus of the films.展开更多
Because of unstable properties of axial mine flow fans working under conditions of low flow rates, the safety and reliability of fans in their operational zone is reduced. At times, serious vibration may bring about t...Because of unstable properties of axial mine flow fans working under conditions of low flow rates, the safety and reliability of fans in their operational zone is reduced. At times, serious vibration may bring about the destruction of equipment or even jeopardize the safety of entire factories. By means of oil flow visualization techniques and numerical simulation, we have investigated the inner-flow of an axial mine flow fan working under low flow rate conditions. The fundamental reasons of complex flow phenomena of the inner-flow of the flow fan under these stated conditions were revealed. At the same time and in order to improve the inner-flow under conditions of low flow rates, a blade separator and air separator were designed. From our tests we found that the blade separator and air separator are two kinds efficient methods to improve the unstable working characteristics of the axial mine flow fan operating under low flow rate conditions. The effect of the improvement of the air separator is stronger than that of the blade separator.展开更多
Valveless piezoelectric pump is widely used in the medical,however,there is a general and difficult problem to be solved:Low vortex and large flow rate are not compatible,resulting in the blood prone to thrombosis dur...Valveless piezoelectric pump is widely used in the medical,however,there is a general and difficult problem to be solved:Low vortex and large flow rate are not compatible,resulting in the blood prone to thrombosis during blood delivery.In this paper,a new valveless piezoelectric(PZT)pump with streamlined flow tubes(streamlined pump)is proposed.The design method and the working principle of the pump are analyzed.The velocity streamlines are simulated,and the results demonstrate that there are no obvious vortexes in the flow tube of the streamlined pump.Five prototype pumps(two cone pumps and three streamlined pumps)are designed and fabricated to perform flow rate and flow resistance experiments.The experimental results illustrate that the maximum flow rate of the streamlined pump is 142 mL/min,which is 179%higher than that of the cone piezoelectric pump,demonstrating that the streamlined pump has a large flow rate performance.This research provides an inspiration for future research on simple structure,low vortex and large flow rate volume-type pumps,and also provides a useful solution for thrombosis preventing.展开更多
This study aimed to obtain the production profiles of oil-in-water flow under low flow rate and high water-cut conditions in oil wells.A combination production profile logging composed of an arc-type conductance senso...This study aimed to obtain the production profiles of oil-in-water flow under low flow rate and high water-cut conditions in oil wells.A combination production profile logging composed of an arc-type conductance sensor(ATCS)and a cross-correlation flow meter(CFM)with a center body is proposed and experimentally evaluated.The ATCS is designed for water holdup measurement,whereas the CFM with a center body is proposed to obtain the mixture velocity.Then,a drift-flux model based on flow patterns is established to predict the individual-phase superficial velocity of oil-in-water flows.Results show that the ATCS possesses high resolution in water holdup measurement and that flow pattern information can be deduced from its signal through nonlinear time series analysis.The CFM can enhance the correlation of upstream and downstream signals and simplify the relationship between the cross-correlation velocity and mixture velocity.On the basis of the drift-flux model,individual-phase superficial velocities can be predicted with high accuracy for different flow patterns.展开更多
The computational flow rate feedback and control method, which can be used in proportional valve controlled hydraulic elevators, is discussed and analyzed. In a hydraulic elevator with this method, microprocessor rece...The computational flow rate feedback and control method, which can be used in proportional valve controlled hydraulic elevators, is discussed and analyzed. In a hydraulic elevator with this method, microprocessor receives pressure information from the pressure transducers and computes the flow rate through the proportional valve based on pressure-flow conversion real time algorithm. This hydraulic elevator is of lower cost and energy consumption than the conventional closed loop control hydraulic elevator whose flow rate is measured by a flow meter. Experiments arc carried out on a test rig which could simulate the load of hydraulic elevator. According to the experiment results, the means to modify the pressure-flow conversion algorithm are pointed out.展开更多
High-pressure solenoid valve with high flow rate and high speed is a key component in an underwater driving system.However,traditional single spool pilot operated valve cannot meet the demands of both high flow rate a...High-pressure solenoid valve with high flow rate and high speed is a key component in an underwater driving system.However,traditional single spool pilot operated valve cannot meet the demands of both high flow rate and high speed simultaneously.A new structure for a high pressure solenoid valve is needed to meet the demand of the underwater driving system.A novel parallel-spool pilot operated high-pressure solenoid valve is proposed to overcome the drawback of the current single spool design.Mathematical models of the opening process and flow rate of the valve are established.Opening response time of the valve is subdivided into 4 parts to analyze the properties of the opening response.Corresponding formulas to solve 4 parts of the response time are derived.Key factors that influence the opening response time are analyzed.According to the mathematical model of the valve,a simulation of the opening process is carried out by MATLAB.Parameters are chosen based on theoretical analysis to design the test prototype of the new type of valve.Opening response time of the designed valve is tested by verifying response of the current in the coil and displacement of the main valve spool.The experimental results are in agreement with the simulated results,therefore the validity of the theoretical analysis is verified.Experimental opening response time of the valve is 48.3 ms at working pressure of 10 MPa.The flow capacity test shows that the largest effective area is 126 mm2 and the largest air flow rate is 2320 L/s.According to the result of the load driving test,the valve can meet the demands of the driving system.The proposed valve with parallel spools provides a new method for the design of a high-pressure valve with fast response and large flow rate.展开更多
Abstract This paper focuses on the stability of capillary forced flow. In space, open capillary channels are widely used as the liquid and gas separation devices to manage liquid positioning and transportation. Surfac...Abstract This paper focuses on the stability of capillary forced flow. In space, open capillary channels are widely used as the liquid and gas separation devices to manage liquid positioning and transportation. Surface collapse happens when the flow rate exceeds the critical value, leading to a failure of propellant management. Knowledge of flow rate limitation is of great significance in design and optimization of propellant management devices （PMDs）. However, the capillary flow rate limitation in an asymmetry channel has not been studied yet in the literature. In this paper, by introducing an equivalent angle to convert the asymmetry corner to a symmetry one, the one-dimensional theoretical model is developed. The flow rate limitation can then be investigated as a function of the channel geometry as well as liquid property based on the model. Comparisons between the asymmetry and symmetry channels bring forth the characteristics of the two kinds of channels, and demonstrate good accordance between the new advanced model and the existing one in the literature. This theoretical model can provide valuable reference for PMD designers.展开更多
基金Projects(52378392,52478390)supported by the National Natural Science Foundation of ChinaProject(2024J08213)supported by the Natural Science Foundation of Fujian Province,China+1 种基金Project(00387088)supported by the“Foal Eagle Program”Youth Top-notch Talent Project of Fujian Province,ChinaProject(GY-Z23072)supported by the Scientific Research Foundation of Fujian University of Technology,China。
文摘Gypsum rocks are highly susceptible to mechanical deterioration under the coupled effects of wet-dry(W-D)cycles and flow rates,which significantly influence the stability of underground excavations.Despite extensive research on the effects of W-D cycles,the coupling influence of flow rates and W-D cycles on gypsum rocks remains poorly understood.This study investigates the mechanical behavior and deterioration mechanisms of gypsum rocks subjected to varying W-D cycles and flow rate conditions.Axial compression tests,along with nuclear magnetic resonance(NMR)techniques,were employed to analyze the stress-strain response and microstructural changes.Based on the disturbed state concept(DSC)theory,a W-D deterioration model and a DSC-based constitutive model were developed to describe the degradation trends and mechanical responses of gypsum rocks under different conditions.The results demonstrate that key mechanical indices,elastic modulus,cohesion,uniaxial compressive strength(UCS),and internal friction angle,exhibit logarithmic declines with increasing W-D cycles,with higher flow rates accelerating the deterioration process.The theoretical models accurately capture the nonlinear compaction behavior,peak stress,and post-peak response of gypsum specimens.This study provides valuable insights for predicting the mechanical behavior of gypsum rocks and improving the stability assessments of underground structures under complex environmental conditions.
基金supported by the National Natural Science Foundation of China(Grant No.U2340221)the National Key R&D Programof China(Grant No.2022YFC3202602)+1 种基金the NaturalScience Foundation of Jiangsu Province(Grant No.BK20230036)the 111 Project(Grant No.B17015)。
文摘Rational allocation of water flow energy in river networks is essential to addressing water-related issues in river network areas.However,current methods of calculating the spatiotemporal distribution of flow energy in river networks lack precision and efficiency.This paper introduces a novel hydrodynamic representation,the energy flow rate,defined as the product of the flow rate and kinetic energy head,to quantify the kinetic energy stored and transported in river networks.A linear equation system for the energy flow rate in a river network has been theoretically derived,enabling rapid calculations under steady flow conditions.A simplified equation is proposed to describe the exponential decay of the energy flow rate,accompanied by potential energy conversion.The coefficients in the linear equation system are determined using control equations at flow confluence and diversion nodes.This study provides foundational insights that can be used to develop new hydrodynamic modeling strategies to regulate water flow energy and achieve coordinated management of water-related issues in river networks.
基金supported by the National Natural Science Foundation of China (Grant No.52104321)the Natural Science Foundation of Chongqing,China (Grant No.CSTB2023NSCQ-MSX0871)the Science and Technology Research Program of Chongqing Municipal Education Commission (Grant No.KJQN202101404).
文摘The two-fluid model coupled with population balance model was used for simulating the gas-liquid flow in the Ruhrstahl-Heraeus(RH)degasser.The predicted circulation flow rate was compared with that measured from a water model experiment to validate the mathematical model.Then,influence of snorkel immersion depth on liquid circulation flow rate was numerically investigated under an atmospheric pressure of 101 and 84 kPa,respectively.Predicted result indicates that the circulation flow rate of the RH degasser in the high-altitude area was severely reduced because of the decrease in atmospheric pressure.However,increasing the snorkel immersion depth from 0.5 to 0.7 m can compensate for the decrease in atmospheric pressure.Industrial test result indicates that decarburization rate is significantly enhanced by increasing the snorkel immersion depth.Through optimization,the percentage of heats with a final carbon content less than 0.002 wt.%is significantly increased from 22.0%to 96.4%.
基金supported by the financial support from the National Natural Science Foundation of China(52204084)Project funded by the China Postdoctoral Science Foundation(2021M700388).
文摘Geothermal energy has gained wide attention as a renewable alternative for mitigating greenhouse gas emissions.The advancements in enhanced geothermal system technology have enabled the exploitation of previously inaccessible geothermal resources.However,the extraction of geothermal energy from deep reservoirs poses many challenges due to high‐temperature and high‐geostress conditions.These factors can significantly impact the surrounding rock and its fracture formation.A comprehensive understanding of the thermal–hydraulic–mechanical(THM)coupling effect is crucial to the safe and efficient exploitation of geothermal resources.This study presented a THM coupling numerical model for the geothermal reservoir of the Yangbajing geothermal system.This proposed model investigated the geothermal exploitation performance and the stress distribution within the reservoir under various combinations of geothermal wells and mass flow rates.The geothermal system performance was evaluated by the criteria of outlet temperature and geothermal productivity.The results indicate that the longer distance between wells can increase the outlet temperature of production wells and improve extraction efficiency in the short term.In contrast,the shorter distance between wells can reduce the heat exchange area and thus mitigate the impact on the reservoir stress.A larger mass flow rate is conducive to the production capacity enhancement of the geothermal system and,in turn causes a wider range of stress disturbance.These findings provide valuable insights into the optimization of geothermal energy extraction while considering reservoir safety and long‐term sustainability.This study deepens the understanding of the THM coupling effects in geothermal systems and provides an efficient and environmentally friendly strategy for a geothermal energy system.
基金supported by the National Natural Science Foundation of China(Grant no.42371136)the Guangdong Basic and Applied Basic Research Foundation(Grant no.2021B1515020032)the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant no.311022003).
文摘Offset-tracking is an essential method for deriving glacier flow rates using optical imagery.Sentinel-2(S2)and Landsat-8/9(L8/9)are popular optical satellites or constellations for polar studies,offering high spatial resolution with relatively short revisit time,wide swath width,and free accessibility.To evaluate and compare the precision of offset-tracking results yielded with these two kinds of data,in this study S2 and L8/9 imagery observed in Petermann Glacier in Greenland,Karakoram in High-Mountains Asia,and Amery Ice Shelf in the Antarctic are analyzed.Outliers and various systematic error sources in the offset-tracking results including orbital and strip errors were analyzed and eliminated at the pre-process stage.Precision at the off-glacier(bare rock)region was evaluated by presuming that no deformation occurred;then for both glacierized and the off-glacier regions,precision of velocity time series was evaluated based on error propagation theory.The least squares method based on connected components was used to solve flow rates time series based on multi-pair images offset-tracking.The results indicated that S2 achieved slightly higher precision than L8/9 in terms of both single-pair derived displacements and least square solved daily flow rates time series.Generally,the RMSE of daily velocity is 26%lower for S2 than L8/9.Moreover,S2 provided higher temporal resolution for monitoring glacier flow rates.
文摘Developing a novel drop counter by introducing the Internet of Things concept has been vigorously conducted in recent years. Understanding the newly introduced drop counter’s flow rate control accuracy and flow rate count feature is essential for improving safety in infusion management. This study aimed to verify if the new drop counters could secure accurate flow rate and drip count by conducting actual flow rate measurements using gravimetry and functional evaluation. A drop counter was attached to each drip chamber of the infusion set, and an IV drip was conducted at the 100 ml/h flow rate. The weight of discharged physiological saline was measured to plot trumpet curves. Next, three different types of drop counters were evaluated to determine if they maintained drip count accuracy according to the changes in their position angles. The flow rate errors in all conditions indicated trumpet-like curves, exhibiting an overall error range within ±10% in all observation windows. Although every drop counter successfully detected and measured dripping, it was challenging in some counters to detect dripping when the drip chamber was tilted. In comparing adult and pediatric IV sets, the adult IV set was found to be less likely to detect dripping in the angled position. No significant differences in results were confirmed between high and low flow rates, suggesting that the drop count function would not be affected by the flow rate in the ranges of typical infusion practices. Doppler sensors have a wide range of measurements and high sensitivity;the dripping was detected successfully even when the drip chamber was tilted, probably due to the advantages of these sensors. In contrast, miscounts occurred in those equipped with infrared sensors, which could not detect light intensity changes in tilted positions. Understanding the tendencies in flow rate errors in infusion can be valuable information for infusion management.
基金Item Sponsored by National Natural Science Foundation of China(51474059,51204042)Program for Liaoning Excellent Talents in University of China(LJQ2014031)Fundamental Research Funds for the Central Universities of China(N140205003)
文摘Based on the similarity principles, a 1 ： 7 scale physical model was established to study the behavior of molten steel flow and inclusion removal in a 145 t Rheinsahl-Heraeus （RH） degasser. On the basis of the quantitative measurements of the circulation flow rate and inclusion removal under various lifting gas flow rates, the effect of circulation flow rate on inclusion removal was investigated in the RH degasser. The inclusion removal rate shows the trend of first increase and then decrease twice with increasing the circulation flow rate when the circulation flow rates are smaller than 104.7 L/min. Whereas, the inclusion removal rate increases again with the further increase in circu- lation flow rate when the circulation flow rate is larger than 104.7 L/min. At lower circulation flow rates, inclusions are mainly removed by Stokes flotation to the slag/steel interface after inclusions are transferred near the slag/steel interface by the circulation flow. At higher circulation flow rates, the collision and aggregation of inclusions improves the inclusion removal efficiency. With the further increase in the circulation flow rate, inclusions are mainly removed by following the turbulent fluctuation （turbulent diffusion） to the slag/steel interface after inclusions are transferred near the slag/steel interface by the circulation flow.
基金supported by the National Natural Science Foundation of China(No.11472304)the Graduate Innovation Grant of Hunan Province(No.CX2017B006),China。
文摘The bleed hole diameter,depth,and boundary layer thickness are key design parameters of a supersonic bleed system.The evolution trend of single-hole bleed flow coefficient with the ratio of boundary layer thickness to bleed hole diameter and the ratio of bleed hole depth to diameter is investigated by numerical simulations under choking and non-choking conditions.The results show that the subsonic leading edge of the circular hole and the subsonic part of the boundary layer are the main factors causing lateral flow of the bleed hole.The effect of diameter on bleed mass flow rate is due to the viscous effect which reduces the effective diameter.The larger the ratio of displacement thickness to bleed hole diameter,the more obvious the viscous effect is.The depth affects bleed flow rate by changing the opening and closing states of the separation zone.When a certain depth is reached,the development of the boundary layer reduces the effective captured stream tube and thus reduces the bleed mass flow rate.The main objective of the study is to obtain the physical mechanism of the bleed hole size parameters affecting the bleed mass flow rate,and to provide theoretical guidance for the selection of the size of bleed holes in the design of a porous arrays bleed system in hypersonic inlets.
基金Project (No. 2001AA413210) supported by the Hi-Tech Researchand Development Program (863) of China
文摘Oil-air two-phase flow measurement was investigated with a Venturi and void fraction meters in this work. This paper proposes a new flow rate measurement correlation in which the effect of the velocity ratio between gas and liquid was considered. With the pressure drop across the Venturi and the void fraction that was measured by electrical capacitance tomography apparatus, both mixture flow rate and oil flow rate could be obtained by the correlation. Experiments included bubble-, slug-, wave and annular flow with the void fraction ranging from 15% to 83%, the oil flow rate ranging from 0.97 kg/s to 1.78 kg/s, the gas flow rate ranging up to 0.018 kg/s and quality ranging nearly up to 2.0%. The root-mean-square errors of mixture mass flow rate and that of oil mass flow rate were less than 5%. Furthermore, coefficients of the correlation were modified based on flow regimes, with the results showing reduced root-mean-square errors.
基金supports of the National Natural Science Foundation of China(No.11472040)the National Science Technology Major Project of China
文摘For spacecraft working in vacuum environment, sublimator is an effective heat rejection approach to reject system's peak heat load, and supplement spacecraft radiation heat rejection. For a spacecraft active fluid loop thermal control system combined with sublimator, waste heat generated from multi-point distributed heat sources could be collected by the fluid loop efficiently. However, the heat and mass transfer performances of the sublimator combined with fluid loop have not been adequately studied in previous research, especially for the influences of the heat load. Since work fluid mass flow rate is the main factor affecting heat load of the fluid loop, this context experimentally studied influences of the fluid loop mass flow rate on sublimator start-up transient characteristics, including heat transfer performances, response time, and work stability. Results indicated that the fluid loop mass flow rate affected the sublimator heat and mass transfer performances obviously, but the heat rejection ability is not always increase with the increasing of the fluid loop mass flow rate. In addition, we obtained the condition to judge whether there is a positive correlation between heat rejection ability and fluid loop mass flow rate.
文摘This paper discussed influences of flow rates of O_2, C_3H_8, and compressedair on the melting degree of particles during HVOF (high velocity oxy-fuel) sprayed CoCrW coating.The O_2 flow rate has the maximal effect on the melting of particles, the C_3H_8 flow rate has thesecond, and the compressed air flow rate has the minimal effect. The bond strength of the HVOFsprayed CoCrW coating is over 54 MPa. The porosity ratio of the HVOF sprayed CoCrW coating afteroptimization of gas flow rates is less than 2%. The average microhardness of the coating is up toHV_(0.1) 545. The oxidation amount per unit area of the HVOF sprayed CoCrW coating increases withthe holding time increasing at 800℃. In the same way, the oxidation amount of the coating increasesas the temperature increases. Particularly, the oxidation of the coating drastically increases over850℃.
基金Supported by the National Natural Science Foundation of China(Nos.51379146,51409190)the National Science Foundation for Post-Doctoral Scientists of China(No.2013M531218)
文摘To investigate the effects of flow rate on phytoplankton dynamics and related environment variables,a set of enclosure experiments with different fl ow rates were conducted in an artificial lake. We monitored nutrients,temperature,dissolved oxygen,p H,conductivity,turbidity,chlorophyll-a and phytoplankton levels. The lower biomass in all flowing enclosures showed that flow rate significantly inhibited the growth of phytoplankton. A critical flow rate occurred near 0.06 m/s,which was the lowest relative inhibitory rate. Changes in flow conditions affected algal competition for light,resulting in a dramatic shift in phytoplankton composition,from blue-green algae in still waters to green algae in flowing conditions. These findings indicate that critical flow rate can be useful in developing methods to reduce algal bloom occurrence. However,flow rate significantly enhanced the inter-relationships among environmental variables,in particular by inducing higher water turbidity and vegetative reproduction of periphyton( Spirogyra). These changes were accompanied by a decrease in underwater light intensity,which consequently inhibited the photosynthetic intensity of phytoplankton. These results warn that a universal critical flow rate might not exist,because the effect of flow rate on phytoplankton is interlinked with many other environmental variables.
文摘Formation water invasion is the most troublesome problem associated with air drilling. However, it is not economical to apply mist drilling when only a small amount of water flows into wellbore from formation during air drilling. Formation water could be circulated out of the wellbore through increasing the gas injection rate. In this paper, the Angel model was modified by introducing Nikurade friction factor for the flow in coarse open holes and translating formation water rate into equivalent penetration rate. Thus the distribution of annular pressure and the relationship between minimum air injection rate and formation water rate were obtained. Real data verification indicated that the modified model is more accurate than the Angel model and can provide useful information for air drilling.
基金supported by the National High Technical Research and Development Program of China (Grant No. 2006AA03Z521)
文摘In this paper,Me （Me=Cr,Zr） and N co-doped diamond like carbon （DLC-MeN） composite films were prepared on cemented carbide substrates by pulsed bias arc ion plating.The effect of nitrogen flow rates on the microstructure and properties of the films were investigated by X-ray photoelectron spectroscopy （XPS）,Raman spectra,grazing incident X-ray diffraction （GIXRD）,high resolution transmission electron microscopy （HRTEM） and nano-indentation.Raman,GIXRD and HRTEM results show that the deposited films are nanocomposite films with MeN nanocrystalline phase embedded within DLC amorphous matrix,which are vital for the mechanical properties of the films.The nitrogen flow rate has significant effect on the compositions and structures and hence on the hardness and elastic modulus of the films,and increasing nitrogen flow rate decreases drastically the hardness and elastic modulus of the films.
文摘Because of unstable properties of axial mine flow fans working under conditions of low flow rates, the safety and reliability of fans in their operational zone is reduced. At times, serious vibration may bring about the destruction of equipment or even jeopardize the safety of entire factories. By means of oil flow visualization techniques and numerical simulation, we have investigated the inner-flow of an axial mine flow fan working under low flow rate conditions. The fundamental reasons of complex flow phenomena of the inner-flow of the flow fan under these stated conditions were revealed. At the same time and in order to improve the inner-flow under conditions of low flow rates, a blade separator and air separator were designed. From our tests we found that the blade separator and air separator are two kinds efficient methods to improve the unstable working characteristics of the axial mine flow fan operating under low flow rate conditions. The effect of the improvement of the air separator is stronger than that of the blade separator.
基金supported by the National Natural Science Foundation of China (No. 51375227)the Introduction of Talent Research Start-up Fund of Nanjing Institute of Technology(No. YKJ201960).
文摘Valveless piezoelectric pump is widely used in the medical,however,there is a general and difficult problem to be solved:Low vortex and large flow rate are not compatible,resulting in the blood prone to thrombosis during blood delivery.In this paper,a new valveless piezoelectric(PZT)pump with streamlined flow tubes(streamlined pump)is proposed.The design method and the working principle of the pump are analyzed.The velocity streamlines are simulated,and the results demonstrate that there are no obvious vortexes in the flow tube of the streamlined pump.Five prototype pumps(two cone pumps and three streamlined pumps)are designed and fabricated to perform flow rate and flow resistance experiments.The experimental results illustrate that the maximum flow rate of the streamlined pump is 142 mL/min,which is 179%higher than that of the cone piezoelectric pump,demonstrating that the streamlined pump has a large flow rate performance.This research provides an inspiration for future research on simple structure,low vortex and large flow rate volume-type pumps,and also provides a useful solution for thrombosis preventing.
基金supported by the National Natural Science Foundation of China(Nos.51527805 and 11572220)
文摘This study aimed to obtain the production profiles of oil-in-water flow under low flow rate and high water-cut conditions in oil wells.A combination production profile logging composed of an arc-type conductance sensor(ATCS)and a cross-correlation flow meter(CFM)with a center body is proposed and experimentally evaluated.The ATCS is designed for water holdup measurement,whereas the CFM with a center body is proposed to obtain the mixture velocity.Then,a drift-flux model based on flow patterns is established to predict the individual-phase superficial velocity of oil-in-water flows.Results show that the ATCS possesses high resolution in water holdup measurement and that flow pattern information can be deduced from its signal through nonlinear time series analysis.The CFM can enhance the correlation of upstream and downstream signals and simplify the relationship between the cross-correlation velocity and mixture velocity.On the basis of the drift-flux model,individual-phase superficial velocities can be predicted with high accuracy for different flow patterns.
基金This project is supported by State Scientific Project of the Tenth Five-year Plan of China(No.2002BA208B02)National Natural Science Foundation of China(No.50305032).
文摘The computational flow rate feedback and control method, which can be used in proportional valve controlled hydraulic elevators, is discussed and analyzed. In a hydraulic elevator with this method, microprocessor receives pressure information from the pressure transducers and computes the flow rate through the proportional valve based on pressure-flow conversion real time algorithm. This hydraulic elevator is of lower cost and energy consumption than the conventional closed loop control hydraulic elevator whose flow rate is measured by a flow meter. Experiments arc carried out on a test rig which could simulate the load of hydraulic elevator. According to the experiment results, the means to modify the pressure-flow conversion algorithm are pointed out.
文摘High-pressure solenoid valve with high flow rate and high speed is a key component in an underwater driving system.However,traditional single spool pilot operated valve cannot meet the demands of both high flow rate and high speed simultaneously.A new structure for a high pressure solenoid valve is needed to meet the demand of the underwater driving system.A novel parallel-spool pilot operated high-pressure solenoid valve is proposed to overcome the drawback of the current single spool design.Mathematical models of the opening process and flow rate of the valve are established.Opening response time of the valve is subdivided into 4 parts to analyze the properties of the opening response.Corresponding formulas to solve 4 parts of the response time are derived.Key factors that influence the opening response time are analyzed.According to the mathematical model of the valve,a simulation of the opening process is carried out by MATLAB.Parameters are chosen based on theoretical analysis to design the test prototype of the new type of valve.Opening response time of the designed valve is tested by verifying response of the current in the coil and displacement of the main valve spool.The experimental results are in agreement with the simulated results,therefore the validity of the theoretical analysis is verified.Experimental opening response time of the valve is 48.3 ms at working pressure of 10 MPa.The flow capacity test shows that the largest effective area is 126 mm2 and the largest air flow rate is 2320 L/s.According to the result of the load driving test,the valve can meet the demands of the driving system.The proposed valve with parallel spools provides a new method for the design of a high-pressure valve with fast response and large flow rate.
基金supported by the National Natural Science Foundation of China(Nos.50975280 and 61004094)
文摘Abstract This paper focuses on the stability of capillary forced flow. In space, open capillary channels are widely used as the liquid and gas separation devices to manage liquid positioning and transportation. Surface collapse happens when the flow rate exceeds the critical value, leading to a failure of propellant management. Knowledge of flow rate limitation is of great significance in design and optimization of propellant management devices （PMDs）. However, the capillary flow rate limitation in an asymmetry channel has not been studied yet in the literature. In this paper, by introducing an equivalent angle to convert the asymmetry corner to a symmetry one, the one-dimensional theoretical model is developed. The flow rate limitation can then be investigated as a function of the channel geometry as well as liquid property based on the model. Comparisons between the asymmetry and symmetry channels bring forth the characteristics of the two kinds of channels, and demonstrate good accordance between the new advanced model and the existing one in the literature. This theoretical model can provide valuable reference for PMD designers.
