Aiming at the dynamic stall problem that restricts the improvement of aircraft maneuverability,a new dynamic stall control method based on leading-edge Dual Synthetic Jets(DSJ)is proposed in this paper.The aerodynamic...Aiming at the dynamic stall problem that restricts the improvement of aircraft maneuverability,a new dynamic stall control method based on leading-edge Dual Synthetic Jets(DSJ)is proposed in this paper.The aerodynamic control characteristics and flow field evolution process of steady jet,Synthetic Jet(SJ)and DSJ in dynamic stall flow field are analyzed in detail,and the corresponding control mechanism is revealed.The strong"wall attachment effect"and quasisteady"characteristics of DSJ are found.The results show that the leading-edge jet technology can improve the dynamic stall flow field environment.For the whole pitching process,the average lift coefficients of steady jet,SJ and DSJ increased by 3.65%,10.51%and 14.62%respectively,and the average drag coefficients decreased by 9.58%,29.9%and 32.0%respectively.In the downward phase,the average lift coefficient increased by 16.31%,26.72%and 35.88%respectively,and the average drag coefficient decreased by 26.21%,50.46%and 54.28%respectively.Due to its strong"wall attachment effect"and"quasi-steady"characteristics,DSJ exhibits optimal control effect,showing its application potential in dynamic stall control.展开更多
We show that low-level jets(LLJs)occurred in 11 out of 22 radiosonde profiles in late austral summer over the coastal region of the Amundsen Sea Embayment,with ten of the LLJs directed offshore.The LLJs had core speed...We show that low-level jets(LLJs)occurred in 11 out of 22 radiosonde profiles in late austral summer over the coastal region of the Amundsen Sea Embayment,with ten of the LLJs directed offshore.The LLJs had core speeds from 9 to 32 m s^(-1),jet core heights from 80 to 800 m,and were associated with strong,low-level temperature inversions.Seven of the observed offshore LLJs were reasonably simulated by the polar-optimized Weather Research and Forecasting(Polar WRF)model,with output from the model subsequently used to elucidate their generation mechanisms.This study shows that one of the offshore LLJs simulated by the Polar WRF was caused by katabatic winds,while the remaining six were caused by the enhancement of katabatic winds by synoptic forcing in response to a low-pressure system over the Bellingshausen Sea,i.e.,the offshore wind component associated with this system plays a crucial role in the enhancement of the katabatic LLJ.Examination of the Polar WRF output further shows that the LLJs extended over large areas of the Amundsen Sea Embayment,resulting in substantially enhanced near-surface wind speeds over both the Thwaites and Pine Island ice shelves,as well as the open ocean over the continental shelf.The wind-driven forcing associated with the LLJs could perhaps have important impacts on the redistribution of snow over the ice shelves significantly,as well as to affecting sea-ice and ocean circulation variability,including the transport of relatively warm water over the continental shelf to the ice shelf cavities and extension basal melting.展开更多
Dual Synthetic Jets (DSJ) can directly affect the development of spray through the complex vortex structure. The mechanism of flow control on spray and its thermal management application are studied by combining exper...Dual Synthetic Jets (DSJ) can directly affect the development of spray through the complex vortex structure. The mechanism of flow control on spray and its thermal management application are studied by combining experiment and simulation. The spray characteristics under different injection angles are studied, and the results show that the angle should be controlled in the range of 45°–60°, so that sufficient momentum transfer can be obtained, and meanwhile spray impingement area narrowing can be avoided. The spray characteristics under flow control of DSJ with different Reynolds numbers are studied, and the results show that Reynolds number should be controlled in the range of 2859–3574, so that strong particle streamwise acceleration and wall film disturbing can be achieved. In addition, the DSJ kinetic energy is utilized more efficiently. On the basis of previous research, this paper proposes a novel active heat pipe based on spray controlled by DSJ. The space occupancy has been reduced by more than 60%. Even in a sealed state, the active heat pipe is able to cool a hot surface with heat flux of 22.2 kW/m^(2) from 111℃ to 57℃ only in 20 s. The noise of DSJ is reduced from 85 dB to 60 dB, which is expected to promote the practical application of DSJ in thermal management.展开更多
To delay the vortex breakdown position of the slender delta wing,this study innovativelyproposes the application of control near the Leading-Edge Vortex(LEV)core sweeping path,whichis called Coupled Core Rotation Dual...To delay the vortex breakdown position of the slender delta wing,this study innovativelyproposes the application of control near the Leading-Edge Vortex(LEV)core sweeping path,whichis called Coupled Core Rotation Dual Synthetic Jets(CCR-DSJ)control.The results show that thevortex breakdown points at each angle of attack are moved backward after control,and the max-imum delayed displacement is 32.4%of the root chord at 30°.Besides,there is a linear relationshipbetween the breakdown position and the angle of attack after control,indicating that CCR-DSJcontrol has a significant effect on the pressure gradient of the vortex axis.Furthermore,the lift coef-ficient C_(L)is enhanced after control,with a maximum CLincrement of 0.078 at 27°,and an effectiveincrement interval of[25°,32°].This interval is different from most previous studies,which isdirectly related to the position of the actuators.According to the lift change mechanism,the anglesof attack are divided into three stages:Stage 1(a=15°–25°),Stage 2(a=25°–32°),and Stage 3(a=32°–40°).In conclusion,CCR-DSJ control can significantly change the pressure distribution,thereby offering promising prospects for the flight stage of the slender delta wing.展开更多
High-power laser pulses interacting with targets can generate intense electromagnetic pulses(EMPs),which can disrupt physical experimental diagnostics and even damage diagnostic equipment,posing a threat to the reliab...High-power laser pulses interacting with targets can generate intense electromagnetic pulses(EMPs),which can disrupt physical experimental diagnostics and even damage diagnostic equipment,posing a threat to the reliable operation of experiments.In this study,EMPs resulting from multi-petawatt laser irradiating nitrogen gas jets were systematically analyzed and investigated.The experimental results revealed that the EMP amplitude is positively correlated with the quantity and energy of the electrons captured and accelerated by the plasma channel.These factors are reflected by parameters such as laser energy and nitrogen gas jet pressure.Additionally,we propose several potential sources of EMPs produced by laser-irradiated gas jets and separately analyzed their spatiotemporal distributions.The findings provide insight into the mechanisms of EMP generation and introduce a new approach to achieve controllable EMPs by regulating the laser energy and gas jet pressure.展开更多
The Textile Technology Centre is the pride of Heberlein.State-of-the-art equipment and a team of top experts guarantee the highest standards of support for customers.Heberlein is the leading provider of air interlacin...The Textile Technology Centre is the pride of Heberlein.State-of-the-art equipment and a team of top experts guarantee the highest standards of support for customers.Heberlein is the leading provider of air interlacing and air texturing jets for synthetic continuous filament yarns and its clients enjoy added value in the form of practical help and guidance on textile processes and economic issues,with a special focus on filament yarn applications.展开更多
Correction to:Nuclear Science and Techniques(2025)36:100 https://doi.org/10.1007/s41365-025-01692-6 In this article,Fig.9 appeared incorrectly and have now been corrected in the original publication.For completeness a...Correction to:Nuclear Science and Techniques(2025)36:100 https://doi.org/10.1007/s41365-025-01692-6 In this article,Fig.9 appeared incorrectly and have now been corrected in the original publication.For completeness and transparency,both correct and incorrect versions are displayed below.展开更多
We identify a point-symmetric morphology of three pairs of ears/clumps in the core-collapse supernova remnant(CCSNR)Puppis A,supporting the jittering jets explosion mechanism(JJEM).In the JJEM,the three pairs of jets ...We identify a point-symmetric morphology of three pairs of ears/clumps in the core-collapse supernova remnant(CCSNR)Puppis A,supporting the jittering jets explosion mechanism(JJEM).In the JJEM,the three pairs of jets that shaped the three pairs of ears/clumps in Puppis A are part of a large set,about 10–30 pairs of jets,that exploded Puppis A.Some similarities in morphological features between CCSNR Puppis A and three multipolar planetary nebulae considered to have been shaped by jets solidify the claim for shaping by jets.Puppis A has a prominent dipole structure,where one side is bright with a well-defined boundary,while the other is faint and defused.The neutron star(NS)has a natal kick velocity in the opposite direction to the denser part of the dipole structure.We propose a new mechanism in the frame of the JJEM that imparts a natal kick to the NS,the kick-byearly asymmetrical pair(kick-BEAP)mechanism.At the early phase of the explosion process,the NS launches a pair of jets where one jet is much more energetic than the counter jet.The more energetic jet compresses a dense side to the CCSNR,and,by momentum conservation,the NS recoils in the opposite direction.Our study supports the JJEM as the primary explosion mechanism of core-collapse supernovae and enriches this explosion mechanism by introducing the novel kick-BEAP mechanism.展开更多
I examine images of 50 planetary nebulae(PNe)with observable post-common envelope evolution(CEE)binary central stars and find that jets are about 40%more common than dense equatorial outflows.Because,in some cases,ene...I examine images of 50 planetary nebulae(PNe)with observable post-common envelope evolution(CEE)binary central stars and find that jets are about 40%more common than dense equatorial outflows.Because,in some cases,energetic jets can compress an equatorial outflow and because fast jets might disperse early in the PN evolution and avoid detection,the CEE process is likelier to launch jets than to eject a dense equatorial outflow by a larger factor than 1.4.In most cases,the companion,mainly a main sequence star,launches the jets as it accretes mass from the envelope of the giant star.By CEE jets,I also refer to jets launched shortly before the onset of the CEE,likely a grazing envelope evolution phase,and shortly after the CEE.The jets and the accretion of mass by the companion before,during,and after the CEE affect envelope mass removal and the final orbital separation.Most numerical simulations of the CEE ignore jets,and those that include jets omit other processes.Despite the considerable progress in the last decade with tens of hydrodynamical simulations of the CEE,we are still far from correctly simulating the CEE.Including jets in simulations of the CEE requires heavy computer resources,but it must be the next step.展开更多
In this paper,we present results from a semi-analytical model that investigates the launching of cold,nonrelativistic jets from a wide radial extent of stationary and axisymmetric magnetized accretion disks.Specifical...In this paper,we present results from a semi-analytical model that investigates the launching of cold,nonrelativistic jets from a wide radial extent of stationary and axisymmetric magnetized accretion disks.Specifically,we examine the effects of magnetization on the disk-jet system in configurations where the magnetic field is near equipartition with the thermal pressure at the disk midplane.In this study,the magnetic strength parameterμis explicitly expressed as a function of the magnetic diffusivity parameter(μ-1/√αm).This formulation provides a more direct link between the magnetic field configuration and the diffusive processes within the accretion disk.By establishing this relationship,we better constrain the role of magnetization in jet launching and explore how variations inμinfluence the overall disk-jet dynamics.We focus on three representative cases whereμtakes the values 0.5,0.7,and 0.9.We solve the stiff ordinary differential equations of the semi-analytical MHD model using the Seulex subroutine of Hairer&Wanner,which employs the Taylor method with adaptive mesh refinement.The resulting solutions are compared with those obtained by Zanni et al.,Tzeferacos et al.,and Stepanovs&Fendt.展开更多
Impinging jet arrays are extensively used in numerous industrial operations,including the cooling of electronics,turbine blades,and other high-heat flux systems because of their superior heat transfer capabilities.Opt...Impinging jet arrays are extensively used in numerous industrial operations,including the cooling of electronics,turbine blades,and other high-heat flux systems because of their superior heat transfer capabilities.Optimizing the design and operating parameters of such systems is essential to enhance cooling efficiency and achieve uniform pressure distribution,which can lead to improved system performance and energy savings.This paper presents two multi-objective optimization methodologies for a turbulent air jet impingement cooling system.The governing equations are resolved employing the commercial computational fluid dynamics(CFD)software ANSYS Fluent v17.The study focuses on four controlling parameters:Reynolds number(Re),swirl number(S),jet-to-jet separation distance(Z/D),and impingement height(H/D).The effects of these parameters on heat transfer and impingement pressure distribution are investigated.Non-dominated Sorting Genetic Algorithm(NSGA-II)and Weighted Sum Method(WSM)are employed to optimize the controlling parameters for maximum cooling performance.The aim is to identify optimal design parameters and system configurations that enhance heat transfer efficiency while achieving a uniform impingement pressure distribution.These findings have practical implications for applications requiring efficient cooling.The optimized design achieved a 12.28%increase in convective heat transfer efficiency with a local Nusselt number of 113.05 compared to 100.69 in the reference design.Enhanced convective cooling and heat flux were observed in the optimized configuration,particularly in areas of direct jet impingement.Additionally,the optimized design maintained lower wall temperatures,demonstrating more effective thermal dissipation.展开更多
Enhancing the fermentation efficiency of waste in waste warehouses is pivotal for accelerating the pyrolysis process and minimizing harmful gas emissions.This study proposes an integrated approach,combining hot air in...Enhancing the fermentation efficiency of waste in waste warehouses is pivotal for accelerating the pyrolysis process and minimizing harmful gas emissions.This study proposes an integrated approach,combining hot air injection with dual atomizing nozzles,for the thermal treatment of waste piles.Numerical simulations are employed to investigate the influence of various parameters,namely,nozzle height,nozzle tilt angle,inlet air velocity and air temperature,on the droplet diffusion process,spread area,droplet temperature,and droplet size distribution.The results show that reducing the nozzle height increases the temperature of droplets upon their deposition on the waste pile.Specifically,when the nozzle height is lowered to 1.5 m,the temperature of the droplets reaching the waste pile is 1℃higher than when the nozzle height is set at 2 m.Furthermore,an increase in the nozzle tilt angle expands the overlapping heating area.For instance,when the nozzle angle is increased from 15°to 30°,the overlapping spread area expands by 3.21 m2.Additionally,increasing the inlet air velocity enhances the droplet diffusion range.At an air velocity of 2 m/s,the droplet diffusion range grows to 14.4 m,representing a 6.7%increase compared to the nowind condition.While the average droplet diameter decreases to 1.53 mm,the droplet temperature decreases by 1℃.Moreover,the droplet temperature is found to become smaller as the ambient temperature inside the waste warehouse declines.Specifically,a 5℃reduction in the ambient temperature results in a 1℃decrease in the average temperature of the atomized droplets.The study concludes that a nozzle height of 1.5 m and a nozzle tilt angle of 30°effectively meet practical heating requirements.展开更多
Jet agitation is known as a maintenance-free stirring technique for nuclear wastewater treatment and demonstrates great potential in transport of radioactive particles.Removal processes of horizontal sediment beds dri...Jet agitation is known as a maintenance-free stirring technique for nuclear wastewater treatment and demonstrates great potential in transport of radioactive particles.Removal processes of horizontal sediment beds driven by impinging jets were experimentally investigated using image capture and processing technique.The beds were composed of heavy fine particles with particle density ranging from 3700 to 12600 kg·m^(-3) and particle diameter from 5 to 100 μm.The jet Reynolds number varied between 4300 and 9600.The single-phase large eddy simulation method was used for calculating both jet flow characteristics and wall shear stresses.The effects of jet strength,particle density,particle diameter,and bed thickness on bed mobility in terms of the critical Shields numbers were considered.Specifically,the critical Shields number was found to be intricately related to properties of particles,and independent of jet intensity.A new Shields number curve for stainless-steel particles was found,and a model was proposed to predict the transport rate of thin beds,with R^(2)=0.96.展开更多
To address the challenges of poor surface quality and high energy consumption in marble cutting,this study introduces an auxiliary abrasive jet cutting technology enhanced by the use of polyacrylamide(PAM)as a dragred...To address the challenges of poor surface quality and high energy consumption in marble cutting,this study introduces an auxiliary abrasive jet cutting technology enhanced by the use of polyacrylamide(PAM)as a dragreducing additive.The effects of feed rate(50-300 mm/min),polymer concentration(0-0.5 g/L),and nozzle spacing(4-12 mm)on kerf width and surface roughness are systematically investigated through an orthogonal experimental design.Results reveal that feed rate emerges as themost significant factor(p<0.01),followed by PAM concentration and nozzle spacing.The optimal set of parameters,comprising a 200 mm/min feed rate,0.3 g/L PAM concentration,and 6mmnozzle spacing,achieves the narrowest kerf width(0.867 mm)and the lowest surface roughness(10.220μm).Analysis of the underlying mechanisms demonstrates that PAMenhances the energy efficiency of the jet by suppressing turbulent pulsations and increasing fluid viscoelasticity,thereby minimizing energy loss during the cutting process.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
Zero mass flux jets, synthesized by acoustic actuators, have been used for the purpose of jet mixing enhancement and jet vectoring. Zero mass flux jets composed of entirely entrained fluid allow momentum transfer into...Zero mass flux jets, synthesized by acoustic actuators, have been used for the purpose of jet mixing enhancement and jet vectoring. Zero mass flux jets composed of entirely entrained fluid allow momentum transfer into the embedding flow. In the present experiments, miniature scale high aspect ratio actuator jets are placed along the long sides and near the exit plane of a primary two dimensional jet. In different modes, the primary jet can be vectored either towards or away from the actuator jets and the jet mixing is enhanced. The disturbance of the excitation frequency is developed while the unstable frequency of the primary jet is completely suppressed.展开更多
Here,we analyze the characteristics and the formation mechanisms of low-level jets(LLJs)in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth genera...Here,we analyze the characteristics and the formation mechanisms of low-level jets(LLJs)in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth generation of the European Centre for Medium-Range Weather Forecasts(ERA5)reanalysis dataset.Our results show that the vertical structure of LLJs is characterized by a predominance of boundary layer jets(BLJs)concentrated at heights of 900-1200 m.The BLJs occur most frequently at 2300 LST(LST=UTC+8 hours)but are strongest at 0200 LST,with composite wind velocities>14 m s^(-1).Synoptic-system-related LLJs(SLLJs)occur most frequently at 0800 LST but are strongest at 1100LST,with composite wind velocities>12 m s^(-1).Both BLJs and SLLJs are characterized by a southwesterly wind direction,although the wind direction of SLLJs is more westerly,and northeasterly SLLJs occur more frequently than northeasterly BLJs.When Wuhan is south of the mei-yu front,the westward extension of the northwest Pacific subtropical high intensifies,and the low-pressure system in the eastern Tibetan Plateau strengthens,favoring the formation of LLJs,which are closely related to precipitation.The wind speeds on rainstorm days are greater than those on LLJ days.Our analysis of four typical heavy precipitation events shows the presence of LLJs at the center of the precipitation and on its southern side before the onset of heavy precipitation.BLJs were shown to develop earlier than SLLJs.展开更多
I review studies of core collapse supernovae(CCSNe) and similar transient events that attribute major roles to jets in powering most CCSNe and in shaping their ejecta. I start with reviewing the jittering jets explosi...I review studies of core collapse supernovae(CCSNe) and similar transient events that attribute major roles to jets in powering most CCSNe and in shaping their ejecta. I start with reviewing the jittering jets explosion mechanism that I take to power most CCSN explosions. Neutrino heating does play a role in boosting the jets. I compare the morphologies of some CCSN remnants to planetary nebulae to conclude that jets and instabilities are behind the shaping of their ejecta. I then discuss CCSNe that are descendants of rapidly rotating collapsing cores that result in fixed-axis jets(with small jittering) that shape bipolar ejecta. A large fraction of the bipolar CCSNe are superluminous supernovae(SLSNe). I conclude that modeling of SLSN light curves and bumps in the light curves must include jets, even when considering energetic magnetars and/or ejecta interaction with the circumstellar matter(CSM). I connect the properties of bipolar CCSNe to common envelope jets supernovae(CEJSNe) where an old neutron star or a black hole spirals-in inside the envelope and then inside the core of a red supergiant. I discuss how jets can shape the pre-explosion CSM, as in Supernova 1987A, and can power pre-explosion outbursts(precursors)in binary system progenitors of CCSNe and CEJSNe. Binary interaction also facilitates the launching of postexplosion jets.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52075538,92271110)Hunan Provincial Natural Science Foundation,China(No.2023JJ30622)the National Science and Technology Major Project,China(Nos.J2019-II-0016-0037,J2019-III-0010-0054).
文摘Aiming at the dynamic stall problem that restricts the improvement of aircraft maneuverability,a new dynamic stall control method based on leading-edge Dual Synthetic Jets(DSJ)is proposed in this paper.The aerodynamic control characteristics and flow field evolution process of steady jet,Synthetic Jet(SJ)and DSJ in dynamic stall flow field are analyzed in detail,and the corresponding control mechanism is revealed.The strong"wall attachment effect"and quasisteady"characteristics of DSJ are found.The results show that the leading-edge jet technology can improve the dynamic stall flow field environment.For the whole pitching process,the average lift coefficients of steady jet,SJ and DSJ increased by 3.65%,10.51%and 14.62%respectively,and the average drag coefficients decreased by 9.58%,29.9%and 32.0%respectively.In the downward phase,the average lift coefficient increased by 16.31%,26.72%and 35.88%respectively,and the average drag coefficient decreased by 26.21%,50.46%and 54.28%respectively.Due to its strong"wall attachment effect"and"quasi-steady"characteristics,DSJ exhibits optimal control effect,showing its application potential in dynamic stall control.
基金support from the European Union’s Horizon 2020 research and innovation framework program under Grant No.101003590(PolarRES)funding from the Indian Institute of Technology Kharagpur and the Ministry of Education,Government of India。
文摘We show that low-level jets(LLJs)occurred in 11 out of 22 radiosonde profiles in late austral summer over the coastal region of the Amundsen Sea Embayment,with ten of the LLJs directed offshore.The LLJs had core speeds from 9 to 32 m s^(-1),jet core heights from 80 to 800 m,and were associated with strong,low-level temperature inversions.Seven of the observed offshore LLJs were reasonably simulated by the polar-optimized Weather Research and Forecasting(Polar WRF)model,with output from the model subsequently used to elucidate their generation mechanisms.This study shows that one of the offshore LLJs simulated by the Polar WRF was caused by katabatic winds,while the remaining six were caused by the enhancement of katabatic winds by synoptic forcing in response to a low-pressure system over the Bellingshausen Sea,i.e.,the offshore wind component associated with this system plays a crucial role in the enhancement of the katabatic LLJ.Examination of the Polar WRF output further shows that the LLJs extended over large areas of the Amundsen Sea Embayment,resulting in substantially enhanced near-surface wind speeds over both the Thwaites and Pine Island ice shelves,as well as the open ocean over the continental shelf.The wind-driven forcing associated with the LLJs could perhaps have important impacts on the redistribution of snow over the ice shelves significantly,as well as to affecting sea-ice and ocean circulation variability,including the transport of relatively warm water over the continental shelf to the ice shelf cavities and extension basal melting.
基金supported by the National Natural Science Foundation of China(Nos.U2341202,12402333).
文摘Dual Synthetic Jets (DSJ) can directly affect the development of spray through the complex vortex structure. The mechanism of flow control on spray and its thermal management application are studied by combining experiment and simulation. The spray characteristics under different injection angles are studied, and the results show that the angle should be controlled in the range of 45°–60°, so that sufficient momentum transfer can be obtained, and meanwhile spray impingement area narrowing can be avoided. The spray characteristics under flow control of DSJ with different Reynolds numbers are studied, and the results show that Reynolds number should be controlled in the range of 2859–3574, so that strong particle streamwise acceleration and wall film disturbing can be achieved. In addition, the DSJ kinetic energy is utilized more efficiently. On the basis of previous research, this paper proposes a novel active heat pipe based on spray controlled by DSJ. The space occupancy has been reduced by more than 60%. Even in a sealed state, the active heat pipe is able to cool a hot surface with heat flux of 22.2 kW/m^(2) from 111℃ to 57℃ only in 20 s. The noise of DSJ is reduced from 85 dB to 60 dB, which is expected to promote the practical application of DSJ in thermal management.
基金supported by the National Natural Science Foundation of China(Nos.92271110,12072352)the Major National Science and Technology Project,China(No.J2019-Ⅲ-0010-0054)。
文摘To delay the vortex breakdown position of the slender delta wing,this study innovativelyproposes the application of control near the Leading-Edge Vortex(LEV)core sweeping path,whichis called Coupled Core Rotation Dual Synthetic Jets(CCR-DSJ)control.The results show that thevortex breakdown points at each angle of attack are moved backward after control,and the max-imum delayed displacement is 32.4%of the root chord at 30°.Besides,there is a linear relationshipbetween the breakdown position and the angle of attack after control,indicating that CCR-DSJcontrol has a significant effect on the pressure gradient of the vortex axis.Furthermore,the lift coef-ficient C_(L)is enhanced after control,with a maximum CLincrement of 0.078 at 27°,and an effectiveincrement interval of[25°,32°].This interval is different from most previous studies,which isdirectly related to the position of the actuators.According to the lift change mechanism,the anglesof attack are divided into three stages:Stage 1(a=15°–25°),Stage 2(a=25°–32°),and Stage 3(a=32°–40°).In conclusion,CCR-DSJ control can significantly change the pressure distribution,thereby offering promising prospects for the flight stage of the slender delta wing.
基金supported by the National Grand Instrument Project(No.2019YFF01014404)the Natural Science Foundation of China(Nos.12122501,61631001,11921006,U2241281,and 11975037)the Foundation of Science and Technology on Plasma Physics Laboratory(No.6142A04220108)。
文摘High-power laser pulses interacting with targets can generate intense electromagnetic pulses(EMPs),which can disrupt physical experimental diagnostics and even damage diagnostic equipment,posing a threat to the reliable operation of experiments.In this study,EMPs resulting from multi-petawatt laser irradiating nitrogen gas jets were systematically analyzed and investigated.The experimental results revealed that the EMP amplitude is positively correlated with the quantity and energy of the electrons captured and accelerated by the plasma channel.These factors are reflected by parameters such as laser energy and nitrogen gas jet pressure.Additionally,we propose several potential sources of EMPs produced by laser-irradiated gas jets and separately analyzed their spatiotemporal distributions.The findings provide insight into the mechanisms of EMP generation and introduce a new approach to achieve controllable EMPs by regulating the laser energy and gas jet pressure.
文摘The Textile Technology Centre is the pride of Heberlein.State-of-the-art equipment and a team of top experts guarantee the highest standards of support for customers.Heberlein is the leading provider of air interlacing and air texturing jets for synthetic continuous filament yarns and its clients enjoy added value in the form of practical help and guidance on textile processes and economic issues,with a special focus on filament yarn applications.
文摘Correction to:Nuclear Science and Techniques(2025)36:100 https://doi.org/10.1007/s41365-025-01692-6 In this article,Fig.9 appeared incorrectly and have now been corrected in the original publication.For completeness and transparency,both correct and incorrect versions are displayed below.
基金A grant from the Pazy Foundation supported this research。
文摘We identify a point-symmetric morphology of three pairs of ears/clumps in the core-collapse supernova remnant(CCSNR)Puppis A,supporting the jittering jets explosion mechanism(JJEM).In the JJEM,the three pairs of jets that shaped the three pairs of ears/clumps in Puppis A are part of a large set,about 10–30 pairs of jets,that exploded Puppis A.Some similarities in morphological features between CCSNR Puppis A and three multipolar planetary nebulae considered to have been shaped by jets solidify the claim for shaping by jets.Puppis A has a prominent dipole structure,where one side is bright with a well-defined boundary,while the other is faint and defused.The neutron star(NS)has a natal kick velocity in the opposite direction to the denser part of the dipole structure.We propose a new mechanism in the frame of the JJEM that imparts a natal kick to the NS,the kick-byearly asymmetrical pair(kick-BEAP)mechanism.At the early phase of the explosion process,the NS launches a pair of jets where one jet is much more energetic than the counter jet.The more energetic jet compresses a dense side to the CCSNR,and,by momentum conservation,the NS recoils in the opposite direction.Our study supports the JJEM as the primary explosion mechanism of core-collapse supernovae and enriches this explosion mechanism by introducing the novel kick-BEAP mechanism.
文摘I examine images of 50 planetary nebulae(PNe)with observable post-common envelope evolution(CEE)binary central stars and find that jets are about 40%more common than dense equatorial outflows.Because,in some cases,energetic jets can compress an equatorial outflow and because fast jets might disperse early in the PN evolution and avoid detection,the CEE process is likelier to launch jets than to eject a dense equatorial outflow by a larger factor than 1.4.In most cases,the companion,mainly a main sequence star,launches the jets as it accretes mass from the envelope of the giant star.By CEE jets,I also refer to jets launched shortly before the onset of the CEE,likely a grazing envelope evolution phase,and shortly after the CEE.The jets and the accretion of mass by the companion before,during,and after the CEE affect envelope mass removal and the final orbital separation.Most numerical simulations of the CEE ignore jets,and those that include jets omit other processes.Despite the considerable progress in the last decade with tens of hydrodynamical simulations of the CEE,we are still far from correctly simulating the CEE.Including jets in simulations of the CEE requires heavy computer resources,but it must be the next step.
文摘In this paper,we present results from a semi-analytical model that investigates the launching of cold,nonrelativistic jets from a wide radial extent of stationary and axisymmetric magnetized accretion disks.Specifically,we examine the effects of magnetization on the disk-jet system in configurations where the magnetic field is near equipartition with the thermal pressure at the disk midplane.In this study,the magnetic strength parameterμis explicitly expressed as a function of the magnetic diffusivity parameter(μ-1/√αm).This formulation provides a more direct link between the magnetic field configuration and the diffusive processes within the accretion disk.By establishing this relationship,we better constrain the role of magnetization in jet launching and explore how variations inμinfluence the overall disk-jet dynamics.We focus on three representative cases whereμtakes the values 0.5,0.7,and 0.9.We solve the stiff ordinary differential equations of the semi-analytical MHD model using the Seulex subroutine of Hairer&Wanner,which employs the Taylor method with adaptive mesh refinement.The resulting solutions are compared with those obtained by Zanni et al.,Tzeferacos et al.,and Stepanovs&Fendt.
文摘Impinging jet arrays are extensively used in numerous industrial operations,including the cooling of electronics,turbine blades,and other high-heat flux systems because of their superior heat transfer capabilities.Optimizing the design and operating parameters of such systems is essential to enhance cooling efficiency and achieve uniform pressure distribution,which can lead to improved system performance and energy savings.This paper presents two multi-objective optimization methodologies for a turbulent air jet impingement cooling system.The governing equations are resolved employing the commercial computational fluid dynamics(CFD)software ANSYS Fluent v17.The study focuses on four controlling parameters:Reynolds number(Re),swirl number(S),jet-to-jet separation distance(Z/D),and impingement height(H/D).The effects of these parameters on heat transfer and impingement pressure distribution are investigated.Non-dominated Sorting Genetic Algorithm(NSGA-II)and Weighted Sum Method(WSM)are employed to optimize the controlling parameters for maximum cooling performance.The aim is to identify optimal design parameters and system configurations that enhance heat transfer efficiency while achieving a uniform impingement pressure distribution.These findings have practical implications for applications requiring efficient cooling.The optimized design achieved a 12.28%increase in convective heat transfer efficiency with a local Nusselt number of 113.05 compared to 100.69 in the reference design.Enhanced convective cooling and heat flux were observed in the optimized configuration,particularly in areas of direct jet impingement.Additionally,the optimized design maintained lower wall temperatures,demonstrating more effective thermal dissipation.
文摘Enhancing the fermentation efficiency of waste in waste warehouses is pivotal for accelerating the pyrolysis process and minimizing harmful gas emissions.This study proposes an integrated approach,combining hot air injection with dual atomizing nozzles,for the thermal treatment of waste piles.Numerical simulations are employed to investigate the influence of various parameters,namely,nozzle height,nozzle tilt angle,inlet air velocity and air temperature,on the droplet diffusion process,spread area,droplet temperature,and droplet size distribution.The results show that reducing the nozzle height increases the temperature of droplets upon their deposition on the waste pile.Specifically,when the nozzle height is lowered to 1.5 m,the temperature of the droplets reaching the waste pile is 1℃higher than when the nozzle height is set at 2 m.Furthermore,an increase in the nozzle tilt angle expands the overlapping heating area.For instance,when the nozzle angle is increased from 15°to 30°,the overlapping spread area expands by 3.21 m2.Additionally,increasing the inlet air velocity enhances the droplet diffusion range.At an air velocity of 2 m/s,the droplet diffusion range grows to 14.4 m,representing a 6.7%increase compared to the nowind condition.While the average droplet diameter decreases to 1.53 mm,the droplet temperature decreases by 1℃.Moreover,the droplet temperature is found to become smaller as the ambient temperature inside the waste warehouse declines.Specifically,a 5℃reduction in the ambient temperature results in a 1℃decrease in the average temperature of the atomized droplets.The study concludes that a nozzle height of 1.5 m and a nozzle tilt angle of 30°effectively meet practical heating requirements.
文摘Jet agitation is known as a maintenance-free stirring technique for nuclear wastewater treatment and demonstrates great potential in transport of radioactive particles.Removal processes of horizontal sediment beds driven by impinging jets were experimentally investigated using image capture and processing technique.The beds were composed of heavy fine particles with particle density ranging from 3700 to 12600 kg·m^(-3) and particle diameter from 5 to 100 μm.The jet Reynolds number varied between 4300 and 9600.The single-phase large eddy simulation method was used for calculating both jet flow characteristics and wall shear stresses.The effects of jet strength,particle density,particle diameter,and bed thickness on bed mobility in terms of the critical Shields numbers were considered.Specifically,the critical Shields number was found to be intricately related to properties of particles,and independent of jet intensity.A new Shields number curve for stainless-steel particles was found,and a model was proposed to predict the transport rate of thin beds,with R^(2)=0.96.
基金supported by the National Natural Science Foundation of China(grant number:52006061)the Key R&D Program of Hunan Province(grant number:2024AQ2001)+2 种基金Scientific Research Program of Hunan Provincial Department of Education(grant number:22B0840)Natural Science Foundation of Hunan Province(grant number:2023JJ50483)Hunan University of Humanities,Science and Technology Graduate Student Research and Innovation Program(ZSCX2024Y06,ZSCX2024Y01).
文摘To address the challenges of poor surface quality and high energy consumption in marble cutting,this study introduces an auxiliary abrasive jet cutting technology enhanced by the use of polyacrylamide(PAM)as a dragreducing additive.The effects of feed rate(50-300 mm/min),polymer concentration(0-0.5 g/L),and nozzle spacing(4-12 mm)on kerf width and surface roughness are systematically investigated through an orthogonal experimental design.Results reveal that feed rate emerges as themost significant factor(p<0.01),followed by PAM concentration and nozzle spacing.The optimal set of parameters,comprising a 200 mm/min feed rate,0.3 g/L PAM concentration,and 6mmnozzle spacing,achieves the narrowest kerf width(0.867 mm)and the lowest surface roughness(10.220μm).Analysis of the underlying mechanisms demonstrates that PAMenhances the energy efficiency of the jet by suppressing turbulent pulsations and increasing fluid viscoelasticity,thereby minimizing energy loss during the cutting process.
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%.
文摘Zero mass flux jets, synthesized by acoustic actuators, have been used for the purpose of jet mixing enhancement and jet vectoring. Zero mass flux jets composed of entirely entrained fluid allow momentum transfer into the embedding flow. In the present experiments, miniature scale high aspect ratio actuator jets are placed along the long sides and near the exit plane of a primary two dimensional jet. In different modes, the primary jet can be vectored either towards or away from the actuator jets and the jet mixing is enhanced. The disturbance of the excitation frequency is developed while the unstable frequency of the primary jet is completely suppressed.
基金supported by the National Natural Science Foundation of China(Grant Nos.42230612,41620104009,41705019,42075186,and 41975058)the Projects of the S&T Development Foundation of the Hubei Meteorological Bureau(Grants No.2021Q04 and 2020Y04)。
文摘Here,we analyze the characteristics and the formation mechanisms of low-level jets(LLJs)in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth generation of the European Centre for Medium-Range Weather Forecasts(ERA5)reanalysis dataset.Our results show that the vertical structure of LLJs is characterized by a predominance of boundary layer jets(BLJs)concentrated at heights of 900-1200 m.The BLJs occur most frequently at 2300 LST(LST=UTC+8 hours)but are strongest at 0200 LST,with composite wind velocities>14 m s^(-1).Synoptic-system-related LLJs(SLLJs)occur most frequently at 0800 LST but are strongest at 1100LST,with composite wind velocities>12 m s^(-1).Both BLJs and SLLJs are characterized by a southwesterly wind direction,although the wind direction of SLLJs is more westerly,and northeasterly SLLJs occur more frequently than northeasterly BLJs.When Wuhan is south of the mei-yu front,the westward extension of the northwest Pacific subtropical high intensifies,and the low-pressure system in the eastern Tibetan Plateau strengthens,favoring the formation of LLJs,which are closely related to precipitation.The wind speeds on rainstorm days are greater than those on LLJ days.Our analysis of four typical heavy precipitation events shows the presence of LLJs at the center of the precipitation and on its southern side before the onset of heavy precipitation.BLJs were shown to develop earlier than SLLJs.
基金supported by a grant from the Israel Science Foundation (769/20)。
文摘I review studies of core collapse supernovae(CCSNe) and similar transient events that attribute major roles to jets in powering most CCSNe and in shaping their ejecta. I start with reviewing the jittering jets explosion mechanism that I take to power most CCSN explosions. Neutrino heating does play a role in boosting the jets. I compare the morphologies of some CCSN remnants to planetary nebulae to conclude that jets and instabilities are behind the shaping of their ejecta. I then discuss CCSNe that are descendants of rapidly rotating collapsing cores that result in fixed-axis jets(with small jittering) that shape bipolar ejecta. A large fraction of the bipolar CCSNe are superluminous supernovae(SLSNe). I conclude that modeling of SLSN light curves and bumps in the light curves must include jets, even when considering energetic magnetars and/or ejecta interaction with the circumstellar matter(CSM). I connect the properties of bipolar CCSNe to common envelope jets supernovae(CEJSNe) where an old neutron star or a black hole spirals-in inside the envelope and then inside the core of a red supergiant. I discuss how jets can shape the pre-explosion CSM, as in Supernova 1987A, and can power pre-explosion outbursts(precursors)in binary system progenitors of CCSNe and CEJSNe. Binary interaction also facilitates the launching of postexplosion jets.
