Integrating photocatalysis technology with peroxymonosulfate oxidation possesses huge potential for degrading stubborn pollutant.Herein,a porous ultra-thin carbon nitride with C-defect O-doping and advanced n-π^(∗)tr...Integrating photocatalysis technology with peroxymonosulfate oxidation possesses huge potential for degrading stubborn pollutant.Herein,a porous ultra-thin carbon nitride with C-defect O-doping and advanced n-π^(∗)transition was customized by one-pot thermalinduced polymerization of molten urea assisted with paraformaldehyde.Via visible-light coupling peroxymonosulfate activation,the DCN-100 can completely photodegrade 2,4-dichlorophenol,and rate constant is 136.6 and 37.9 times that of CN and DCN-100 without peroxymonosulfate.The light-absorption of DCN-100 surpasses 550 nm,specific surface area rises from 45.03 to 98.58m^(2)/g,and charge behaviors are significantly improved.The effects of paraformaldehyde amount,PMS dosage,pH,2,4-dichlorophenol concentration,different water-body,wavelength and recycling times on photodegradation performance were explored in detail.Via capture experiments,ESR,LC-MS,Fukui-function,TEXT toxicity assessment and DFT theoretical calculation,themain active substances,degradation pathway,intermediate toxicity and enhanced activity mechanism of DCN-100 were clarified.The research provides a cost-effective,high-efficiency and environmental-friendly photocatalysts to activate peroxymonosulfate for water remediating.展开更多
Pressure-gain combustion has gained attention for airbreathing ramjet engine applications owing to its better thermodynamic efficiency and fuel consumption rate. In contrast with traditional detonation induced by a si...Pressure-gain combustion has gained attention for airbreathing ramjet engine applications owing to its better thermodynamic efficiency and fuel consumption rate. In contrast with traditional detonation induced by a single wedge, the present study considers oblique shock interactions attached to double wedges in a hypersonic combustible flow. The temperature/pressure increases sharply across the interaction zone that initiates an exothermic reaction, finally resulting in an Oblique Detonation Wave(ODW). Compared with the case for a single-wedge ODW, the double-wedge geometry has great potential to control the initiation of the ODW. As a tentative study, two-dimensional compressible Euler equations with a two-step induction-reaction kinetic model are used to solve the detonation dynamics triggered by a double wedge. The effects of the wedge angles and wedge corner locations on the initiation structures are investigated numerically.The results show an ODW complex comprising three Oblique Shock Waves(OSWs), an induction zone, a curved detonation front, and an unburned/low-temperature gas belt close to the surface of the second wedge. Both the increasing wedge angle and downstream wedge corner location lead to an abrupt OSW–ODW transition type, whereas the former corresponds to the shock–shock interaction and the later has a greater effect on the exothermic chemical process. Analysis of the shock polar and flow scale confirms that the OSW–ODW initiation structure mainly depends on the coupling of shocks and heat release in a confined initiation zone.展开更多
This paper examines the Shock/Shock Interactions（SSI）between the body and wing of aircraft in supersonic flows.The body is simplified to a flat wedge and the wing is assumed to be a sharp wing.The theoretical spatia...This paper examines the Shock/Shock Interactions（SSI）between the body and wing of aircraft in supersonic flows.The body is simplified to a flat wedge and the wing is assumed to be a sharp wing.The theoretical spatial dimension reduction method,which transforms the 3D problem into a 2D one,is used to analyze the SSI between the body and wing.The temperature and pressure behind the Mach stem induced by the wing and body are obtained,and the wave configurations in the corner are determined.Numerical validations are conducted by solving the inviscid Euler equations in 3D with a Non-oscillatory and Non-free-parameters Dissipative（NND）finite difference scheme.Good agreements between the theoretical and numerical results are obtained.Additionally,the effects of the wedge angle and sweep angle on wave configurations and flow field are considered numerically and theoretically.The influences of wedge angle are significant,whereas the effects of sweep angle on wave configurations are negligible.This paper provides useful information for the design and thermal protection of aircraft in supersonic and hypersonic flows.展开更多
The properties of Mach stems in hypersonic corner flow induced by Mach interaction over 3D intersecting wedges were studied theoretically and numerically.A new method called ＂spatial dimension reduction＂ was used to...The properties of Mach stems in hypersonic corner flow induced by Mach interaction over 3D intersecting wedges were studied theoretically and numerically.A new method called ＂spatial dimension reduction＂ was used to analyze theoretically the location and Mach number behind Mach stems. By using this approach, the problem of 3D steady shock/shock interaction over 3D intersecting wedges was transformed into a 2D moving one on cross sections, which can be solved by shock-polar theory and shock dynamics theory. The properties of Mach interaction over 3D intersecting wedges can be analyzed with the new method,including pressure, temperature, density in the vicinity of triple points, location, and Mach number behind Mach stems.Theoretical results were compared with numerical results,and good agreement was obtained. Also, the influence of Mach number and wedge angle on the properties of a 3D Mach stem was studied.展开更多
Oblique detonation wave(ODW)has been investigated widely for application in ramjet-type engines,but there are less works concerning its instability in a confined space.Recently,a wave complex induced by ODW decoupling...Oblique detonation wave(ODW)has been investigated widely for application in ramjet-type engines,but there are less works concerning its instability in a confined space.Recently,a wave complex induced by ODW decoupling has been observed,and this study investigates the instability of this wave complex featuring a recirculation zone.Numerical results show that the wave complex with recirculation zone oscillates,but the oscillations are found to be periodic rather than random,never reported before.The dependence of the period and frequency on the corner location and angle are analyzed in detail,with very irregular motion tracks of recirculation zone cores.Further quantitative analysis by Fast Fourier transformation reveals two origins of instability:one is the basic oscillation of the recirculation zone associated with the movement of surrounding wave complex;the other is self-excitation inside the recirculation zone,which makes its motion tracks more complicated than the external wave configuration.展开更多
The dynamics of frontal and transverse shocks in gaseous detonation waves is a complex phenomenon bringing many difficulties to both numerical and experimental research.Advanced laser-optical visualization of detonati...The dynamics of frontal and transverse shocks in gaseous detonation waves is a complex phenomenon bringing many difficulties to both numerical and experimental research.Advanced laser-optical visualization of detonation structure may provide certain information of its reactive front,but the corresponding lead shock needs to be reconstructed building the complete flow field.Using the multi-layer perceptron(MLP)approach,we propose a shock front reconstruction method which can predict evolution of the lead shock wavefront from the state of the reactive front.The method is verified through the numerical results of one-and two-dimensional unstable detonations based on the reactive Euler equations with a one-step irreversible chemical reaction model.Results show that the accuracy of the proposed method depends on the activation energy of the reactive mixture,which influences prominently the cellular detonation instability and hence,the distortion of the lead shock surface.To select the input variables for training and evaluate their influence on the effectiveness of the proposed method,five groups,one with six variables,and the other with four variables,are tested and analyzed in the MLP model.The trained MLP is tested in the cases with different activation energies,demonstrates the inspiring generalization capability.This paper offers a universal framework for predicting detonation frontal evolution and provides a novel way to interpret numerical and experimental results of detonation waves.展开更多
基金supported by the Natural Science Foundation Project of Jilin Province(Nos.20230101297JC,YDZJ202201ZYTS347,YDZJ202101ZYTS073,20210101117JC,YDZJ202201ZYTS349,YDZJ202102CXJD049)the National Natural Science Foundation(22004047)+4 种基金China Postdoctoral Science Foundation(No.2023M731299)the Project of Jilin Province Development and Reform Commission(Nos.2023C032-5,2023C032-4,2023C032-2)the Project of Human Resources and Social Security Department of Jilin Province(No.2023337)the National College students’innovation and entrepreneurship training program(No.202310203008)the Project of Education Department of Jilin Province(Nos.JJKH20220429KJ,JJKH20210460KJ).
文摘Integrating photocatalysis technology with peroxymonosulfate oxidation possesses huge potential for degrading stubborn pollutant.Herein,a porous ultra-thin carbon nitride with C-defect O-doping and advanced n-π^(∗)transition was customized by one-pot thermalinduced polymerization of molten urea assisted with paraformaldehyde.Via visible-light coupling peroxymonosulfate activation,the DCN-100 can completely photodegrade 2,4-dichlorophenol,and rate constant is 136.6 and 37.9 times that of CN and DCN-100 without peroxymonosulfate.The light-absorption of DCN-100 surpasses 550 nm,specific surface area rises from 45.03 to 98.58m^(2)/g,and charge behaviors are significantly improved.The effects of paraformaldehyde amount,PMS dosage,pH,2,4-dichlorophenol concentration,different water-body,wavelength and recycling times on photodegradation performance were explored in detail.Via capture experiments,ESR,LC-MS,Fukui-function,TEXT toxicity assessment and DFT theoretical calculation,themain active substances,degradation pathway,intermediate toxicity and enhanced activity mechanism of DCN-100 were clarified.The research provides a cost-effective,high-efficiency and environmental-friendly photocatalysts to activate peroxymonosulfate for water remediating.
基金supported by the National Natural Science Foundation of China(No.11822202)。
文摘Pressure-gain combustion has gained attention for airbreathing ramjet engine applications owing to its better thermodynamic efficiency and fuel consumption rate. In contrast with traditional detonation induced by a single wedge, the present study considers oblique shock interactions attached to double wedges in a hypersonic combustible flow. The temperature/pressure increases sharply across the interaction zone that initiates an exothermic reaction, finally resulting in an Oblique Detonation Wave(ODW). Compared with the case for a single-wedge ODW, the double-wedge geometry has great potential to control the initiation of the ODW. As a tentative study, two-dimensional compressible Euler equations with a two-step induction-reaction kinetic model are used to solve the detonation dynamics triggered by a double wedge. The effects of the wedge angles and wedge corner locations on the initiation structures are investigated numerically.The results show an ODW complex comprising three Oblique Shock Waves(OSWs), an induction zone, a curved detonation front, and an unburned/low-temperature gas belt close to the surface of the second wedge. Both the increasing wedge angle and downstream wedge corner location lead to an abrupt OSW–ODW transition type, whereas the former corresponds to the shock–shock interaction and the later has a greater effect on the exothermic chemical process. Analysis of the shock polar and flow scale confirms that the OSW–ODW initiation structure mainly depends on the coupling of shocks and heat release in a confined initiation zone.
基金supported by the Fundamental Research Funds for the Central Universities of China (No. 31020170QD087)
文摘This paper examines the Shock/Shock Interactions（SSI）between the body and wing of aircraft in supersonic flows.The body is simplified to a flat wedge and the wing is assumed to be a sharp wing.The theoretical spatial dimension reduction method,which transforms the 3D problem into a 2D one,is used to analyze the SSI between the body and wing.The temperature and pressure behind the Mach stem induced by the wing and body are obtained,and the wave configurations in the corner are determined.Numerical validations are conducted by solving the inviscid Euler equations in 3D with a Non-oscillatory and Non-free-parameters Dissipative（NND）finite difference scheme.Good agreements between the theoretical and numerical results are obtained.Additionally,the effects of the wedge angle and sweep angle on wave configurations and flow field are considered numerically and theoretically.The influences of wedge angle are significant,whereas the effects of sweep angle on wave configurations are negligible.This paper provides useful information for the design and thermal protection of aircraft in supersonic and hypersonic flows.
基金supported by the National Natural Science Foundation of China (Grants 11372333, 90916028)
文摘The properties of Mach stems in hypersonic corner flow induced by Mach interaction over 3D intersecting wedges were studied theoretically and numerically.A new method called ＂spatial dimension reduction＂ was used to analyze theoretically the location and Mach number behind Mach stems. By using this approach, the problem of 3D steady shock/shock interaction over 3D intersecting wedges was transformed into a 2D moving one on cross sections, which can be solved by shock-polar theory and shock dynamics theory. The properties of Mach interaction over 3D intersecting wedges can be analyzed with the new method,including pressure, temperature, density in the vicinity of triple points, location, and Mach number behind Mach stems.Theoretical results were compared with numerical results,and good agreement was obtained. Also, the influence of Mach number and wedge angle on the properties of a 3D Mach stem was studied.
基金supported by the National Natural Science Foundation of China(Grant Nos.12002041 and 11822202)。
文摘Oblique detonation wave(ODW)has been investigated widely for application in ramjet-type engines,but there are less works concerning its instability in a confined space.Recently,a wave complex induced by ODW decoupling has been observed,and this study investigates the instability of this wave complex featuring a recirculation zone.Numerical results show that the wave complex with recirculation zone oscillates,but the oscillations are found to be periodic rather than random,never reported before.The dependence of the period and frequency on the corner location and angle are analyzed in detail,with very irregular motion tracks of recirculation zone cores.Further quantitative analysis by Fast Fourier transformation reveals two origins of instability:one is the basic oscillation of the recirculation zone associated with the movement of surrounding wave complex;the other is self-excitation inside the recirculation zone,which makes its motion tracks more complicated than the external wave configuration.
基金This work was supported by the National Natural Science Foundation of China(Grant 11822202).
文摘The dynamics of frontal and transverse shocks in gaseous detonation waves is a complex phenomenon bringing many difficulties to both numerical and experimental research.Advanced laser-optical visualization of detonation structure may provide certain information of its reactive front,but the corresponding lead shock needs to be reconstructed building the complete flow field.Using the multi-layer perceptron(MLP)approach,we propose a shock front reconstruction method which can predict evolution of the lead shock wavefront from the state of the reactive front.The method is verified through the numerical results of one-and two-dimensional unstable detonations based on the reactive Euler equations with a one-step irreversible chemical reaction model.Results show that the accuracy of the proposed method depends on the activation energy of the reactive mixture,which influences prominently the cellular detonation instability and hence,the distortion of the lead shock surface.To select the input variables for training and evaluate their influence on the effectiveness of the proposed method,five groups,one with six variables,and the other with four variables,are tested and analyzed in the MLP model.The trained MLP is tested in the cases with different activation energies,demonstrates the inspiring generalization capability.This paper offers a universal framework for predicting detonation frontal evolution and provides a novel way to interpret numerical and experimental results of detonation waves.
