This paper presents the design and verification of the dual-mode core driven fan stage(CDFS)and high-load compressor with a large flow regulation range.In view of the characteristics of large flow regulation range of ...This paper presents the design and verification of the dual-mode core driven fan stage(CDFS)and high-load compressor with a large flow regulation range.In view of the characteristics of large flow regulation range of the two modes and high average stage load coefficient,this paper investigates the design technology of the dual-mode high-efficiency compressor with a large flow regulation range and high-load compressor with an average stage load coefficient of 0.504.Building upon this research,the design of the dual-mode CDFS and four-stage compressor is completed,and three-dimensional numerical simulation of the two modes is carried out.Finally,performance experiment is conducted to verify the result of three-dimensional numerical simulation.The experiment results show that the compressor performance is improved for the whole working conditions by using the new design method,which realizes the complete fusion design of the CDFS and high-pressure compressor(HPC).The matching mechanism of stage characteristics of single and double bypass modes and the variation rule of different adjustment angles on performance are studied comprehensively.Furthermore,it effectively reduces the length and weight of compressor,and breaks through the key technologies such as high-load compressor with the average load factor of 0.504.These findings provide valuable data and a methodological foundation for the development of the next generation aeroengine.展开更多
Anisotropic hyperbolic phonon polaritons(PhPs)in natural biaxial hyperbolic materialα-MoO_(3) has opened up new avenues for mid-infrared nanophotonics,while active tunability ofα-MoO_(3) PhPs is still an urgent prob...Anisotropic hyperbolic phonon polaritons(PhPs)in natural biaxial hyperbolic materialα-MoO_(3) has opened up new avenues for mid-infrared nanophotonics,while active tunability ofα-MoO_(3) PhPs is still an urgent problem necessarily to be solved.In this study,we present a theoretical demonstration of actively tuningα-MoO_(3) PhPs using phase change material VO_(2) and graphene.It is observed thatα-MoO_(3) PhPs are greatly dependent on the propagation plane angle of PhPs.The insulator-to-metal phase transition of VO_(2) has a significant effect on the hybridization PhPs of theα-MoO_(3)/VO_(2) structure and allows to obtain actively tunableα-MoO_(3) PhPs,which is especially obvious when the propagation plane angle of PhPs is 900.Moreover,when graphene surface plasmon sources are placed at the top or bottom ofα-MoO_(3) inα-MoO_(3)/VO_(2)structure,tunable coupled hyperbolic plasmon-phonon polaritons inside its Reststrahlen bands(RB s)and surface plasmonphonon polaritons outside its RBs can be achieved.In addition,the above-mentionedα-MoO_(3)-based structures also lead to actively tunable anisotropic spontaneous emission(SE)enhancement.This study may be beneficial for realization of active tunability of both PhPs and SE ofα-MoO_(3),and facilitate a deeper understanding of the mechanisms of anisotropic light-matter interaction inα-MoO_(3) using functional materials.展开更多
The further development of catalytic elements has been plagued by activation and binary problems.The automatic shift model that has emerged in recent years helps components achieve full range.However,the detection dat...The further development of catalytic elements has been plagued by activation and binary problems.The automatic shift model that has emerged in recent years helps components achieve full range.However,the detection data still remains unstable in the shift area(7%∼13%).This paper proposes a Catalytic Combustion and Thermal Conductivity(CCTC)model for the specified range,which can be explained fromtwo aspects based on the existing methods.On the one hand,it uses iterative location search to process heterogeneous data,judges the prediction position of data points,and then givesweight evaluation.On the other hand,it corrects the abnormal points,determines the abnormal points in the horizontal direction,and gives the replacement value through the data of adjacent points.The experimental results show that the CCTC model reduces the sum of variance from 17 of the automatic shift model to 13,and the comparison of experimental variance is reduced by 23%.In the full-scale real-time data,the experimental variance of CCTC model and automatic shift model is reduced by 18%.In conclusion,CCTC is a cross section stability framework for full-scale methane measurement,in which the specified heterogeneous combination and anomaly point correction methods improve the stability.展开更多
This article presents a device for the storage and gasification of cryogenic working fluid,which is named a cryogenic fuelling tank.A cryogenic fuel tank can serve both as a fuel vessel and a pressure accumulator due ...This article presents a device for the storage and gasification of cryogenic working fluid,which is named a cryogenic fuelling tank.A cryogenic fuel tank can serve both as a fuel vessel and a pressure accumulator due to the regasification process that takes place inside.Application of this tank is slowed by the lack of theoretical and experimental research on its working process.This article deals with an investigation of the working process of the energy plant based on a cryogenic fuel tank coupled with a rotor-vane expander.Developed mathematical models include evaporation and condensation processes within the tank,heat exchange between gas chambers and between the tank and environment,and changes in energy due to incoming and leaving mass.Mechanical work used to determine the efficiency of a power plant is generated by a steam expander.Research shows that it is possible to achieve specific work outputs up to 110-160 kJ/kg with relative deviation of power and specific work determination equal to 1.4% and 1.9%correspondingly.展开更多
Relative rotation between the emitter and receiver could effectively modulate the near-field radiative heat transfer(NFRHT)in anisotropic media.Due to the strong in-plane anisotropy,natural hyperbolic materials can be...Relative rotation between the emitter and receiver could effectively modulate the near-field radiative heat transfer(NFRHT)in anisotropic media.Due to the strong in-plane anisotropy,natural hyperbolic materials can be used to construct near-field radiative modulators with excellent modulation effects.However,in practical applications,natural hyperbolic materials need to be deposited on the substrate,and the influence of substrate on modulation effect has not been studied yet.In this work,we investigate the influence of substrate effect on near-field radiative modulator based onα-MoO_(3).The results show that compared to the situation without a substrate,the presence of both lossless and lossy substrate will reduce the modulation contrast(MC)for different film thicknesses.When the real or imaginary component of the substrate permittivity increases,the mismatch of hyperbolic phonon polaritons(HPPs)weakens,resulting in a reduction in MC.By reducing the real and imaginary components of substrate permittivity,the MC can be significantly improved,reaching 4.64 forε_(s)=3 at t=10 nm.This work indicates that choosing a substrate with a smaller permittivity helps to achieve a better modulation effect,and provides guidance for the application of natural hyperbolic materials in the near-field radiative modulator.展开更多
Due to the strong unsteadiness of pulse detonation,large flow losses are generated when the detonation wave interacts with the turbine blades,resulting in low turbine efficiency.Considering that the flow losses are di...Due to the strong unsteadiness of pulse detonation,large flow losses are generated when the detonation wave interacts with the turbine blades,resulting in low turbine efficiency.Considering that the flow losses are dissipated into the gas as heat energy,some of them can be recycled during the expansion process in subsequent stages by the reheat effect,which should be helpful to improve the detonationdriven turbine efficiency.Taking this into account,this paper developed a numerical model of the detonation chamber coupled with a two-stage axial turbine,and a stoichiometric hydrogen-air mixture was used.The improvement in turbine efficiency attributable to the reheat effect was calculated by comparing the average efficiency of the stages with the efficiency of the two-stage turbine.The research indicated that the first stage was critical in suppressing the flow unsteadiness caused by pulse detonation,which stabilized the intake condition of the second stage and consequently allowed much of the flow losses from the first stage to be recycled,so that the efficiency of the two-stage turbine was improved.At a 95%confidence level,the efficiency improvement was stable at 4.5%—5.3%,demonstrating that the reheat effect is significant in improving the efficiency of the detonation-driven turbine.展开更多
The time domain harmonic balance method is an attractive reduced order method of analyzing unsteady flow for turbomachines. However, the method can admit non-physical solutions. Non-physical solutions were encountered...The time domain harmonic balance method is an attractive reduced order method of analyzing unsteady flow for turbomachines. However, the method can admit non-physical solutions. Non-physical solutions were encountered from a three-blade-row compressor configuration in a time domain harmonic balance analysis. This paper aims to investigate the root cause of the non-physical solutions. The investigation involves several strategies, which include increasing the number of harmonics, increasing the number of time instants, including scattered modes,including the rotor-rotor interaction, and the use of a new method-the approximate time domain nonlinear harmonic method. Numerical analyses pertinent to each strategy are presented to reveal the root cause of the non-physical solution. It is found that the nonlinear interaction of unsteady flow components with different fundamental frequencies is the cause of the non-physical solution. The non-physical solution can be eliminated by incorporating extra scattered modes or using the approximate time domain nonlinear harmonic method.展开更多
The elastic support/dry friction damper is a type of damper which is used for active vibration control in a rotor system.To establish the analytical model of this type of damper,a two-dimensional friction model-ball/p...The elastic support/dry friction damper is a type of damper which is used for active vibration control in a rotor system.To establish the analytical model of this type of damper,a two-dimensional friction model-ball/plate model was proposed.By using this ball/plate model,a dynamics model of rotor with elastic support/dry friction dampers was established and experimentally verified.Moreover,the damping performance of the elastic support/dry friction damper was studied numerically with respect to some variable parameters.The numerical study shows that the damping performance of the elastic support/dry friction damper is closely related to the stiffness distribution of the rotor-support system,the damper location,the pressing force between the moving and stationary disk,the friction coefficient,the tangential contact stiffness of the contact interface,and the stiffness of the stationary disk.In general,the damper should be located on an elastic support which has a large vibration amplitude in order to achieve a better damping performance,and the more vibration energy in this elastic support concentrates,the better performance of the damper will be.The larger the tangential contact stiffness of the contact interface,and the stiffness of the stationary disk are,the better performance of the damper will be.There will be an optimal value of the friction force at which the damper performs best.展开更多
The multi-dimensional time-domain computational fluid dynamics(CFD) approach is extended to calculate the acoustic attenuation performance of water-filled piping silencers. Transmission loss predictions from the time-...The multi-dimensional time-domain computational fluid dynamics(CFD) approach is extended to calculate the acoustic attenuation performance of water-filled piping silencers. Transmission loss predictions from the time-domain CFD approach and the frequency-domain finite element method(FEM) agree well with each other for the dual expansion chamber silencer, straight-through and cross-flow perforated tube silencers without flow. Then, the time-domain CFD approach is used to investigate the effect of flow on the acoustic attenuation characteristics of perforated tube silencers. The numerical predictions demonstrate that the mean flow increases the transmission loss, especially at higher frequencies, and shifts the transmission loss curve to lower frequencies.展开更多
Nonlinear wave equations have been extensively investigated in the last sev- eral decades. The Landau-Ginzburg-Higgs equation, a typical nonlinear wave equation, is studied in this paper based on the multi-symplectic ...Nonlinear wave equations have been extensively investigated in the last sev- eral decades. The Landau-Ginzburg-Higgs equation, a typical nonlinear wave equation, is studied in this paper based on the multi-symplectic theory in the Hamilton space. The multi-symplectic Runge-Kutta method is reviewed, and a semi-implicit scheme with certain discrete conservation laws is constructed to solve the first-order partial differential equations （PDEs） derived from the Landau-Ginzburg-Higgs equation. The numerical re- sults for the soliton solution of the Landau-Ginzburg-Higgs equation are reported, showing that the multi-symplectic Runge-Kutta method is an efficient algorithm with excellent long-time numerical behaviors.展开更多
With the development of modern technology and economy,environmental protection and sustainable development have become the focus of global attention.The promotion and development of electric vehicles(EVs)have bright p...With the development of modern technology and economy,environmental protection and sustainable development have become the focus of global attention.The promotion and development of electric vehicles(EVs)have bright prospects.However,many challenges need to be faced seriously.Under diferent operating conditions,various safety problems of electric vehicles emerge one after another,especially the hidden danger of battery overheating which threatens the performance of electric vehicles.This paper aims to design and optimize a new indirect liquid cooling system for cylindrical lithium-ion batteries.Various design schemes for diferent cooling channel structures and cooling liquid inlet directions are proposed,and the corresponding solid-fuid coupling model is established.COMSOL Multiphysics simulation software is adopted to simulate and analyze the cooling systems.An approximate model is constructed using the Kriging method,which is considered to optimize the battery cooling system and improve the optimization results.Sensitivity parameter analysis and the optimization design of system structure are performed through a set of infuencing factors in the battery thermal management.The results indicate that the method used in this paper can efectively reduce the maximum core temperature and balance the temperature diferences of the battery pack.Compared with the original design,the optimized design,which is based on the non-dominated sorting genetic algorithm(NSGA-II),has an excellent ability in the optimized thermal management system to dissipate thermal energy and keep the overall cooling uniformity of the battery and thermal management system.Furthermore,the optimized system can also prevent thermal runaway propagation under thermal abuse conditions.In summary,this research can provide some practical suggestions and ideas for the engineering and production applications and structural optimization design carried by electric vehicles.展开更多
A PID parameters tuning and optimization method for a turbine engine based on the simplex search method was proposed. Taking time delay of combustion and actuator into account, a simulation model of a PID control syst...A PID parameters tuning and optimization method for a turbine engine based on the simplex search method was proposed. Taking time delay of combustion and actuator into account, a simulation model of a PID control system for a turbine engine was developed. A performance index based on the integral of absolute error （IAE） was given as an objective function of optimization. In order to avoid the sensitivity that resulted from the initial values of the simplex search method, the traditional Ziegler-Nichols method was used to tune PID parameters to obtain the initial values at first, then the simplex search method was applied to optimize PID parameters for the turbine engine. Simulation results indicate that the simplex search method is a reasonable and effective method for PID controller parameters tuning and optimization.展开更多
Highly efficient and stable hybrid white organic light-emitting diodes （HWOLEDs） with a mixed bipolar interlayer between fluorescent blue and phosphorescent yellow emitting layers are demonstrated. The bipolar inter...Highly efficient and stable hybrid white organic light-emitting diodes （HWOLEDs） with a mixed bipolar interlayer between fluorescent blue and phosphorescent yellow emitting layers are demonstrated. The bipolar interlayer is a mixture of p-type diphenyl （l0-phenyl-lOH-spiro [acridine-9,9＇-fluoren]-3Lyl） phosphine oxide and n-type 2＇,2- （1,3,5-benzinetriyl）-tris（1-phenyl-l-H-benzimidazole）. The electroluminance and Commission Internationale de l＇Eclairage （CIE1931） coordinates＇ characteristics can be modulated easily by adjusting the ratio of the hole- predominated material to the electron-predominated material in the interlayer. The hybrid WOLED with a p-type：n-type ratio of 1：3 shows a maximum current efficiency and power efficiency of 61.1 ed/A and 55.8 lm/W, respectively, with warm white CIE coordinates of （0.34, 0.43）. The excellent efficiency and adaptive CIE coordi- nates are attributed to the mixed interlayer with improved charge carrier balance, optimized exciton distribution, and enhanced harvesting of singlet and triplet excitons.展开更多
The scramjet, which is the propulsion of hypersonic vehicle, has become the focus in many military developed countries. The ground tests play an important role in the research of scramjet. There is defect of test medi...The scramjet, which is the propulsion of hypersonic vehicle, has become the focus in many military developed countries. The ground tests play an important role in the research of scramjet. There is defect of test medium contamination （the thermochemical characteristic of the ground test medium is different from that of the flight medium） in existing ground test facilities for scramjet combustor experiment. To solve the problem of test medium contamination, the first clean air heated facility of China for scramjet combustor experiment is designed. The key technology of designing the clean air heated facility is summarized. By using bypass duct, combustor model is protected from high temperature. To reduce the switching time between main duct and bypass duct, solenoid valve and water-cooled system were used. Having centrosymmetric structure, the heat radiating area of the facility and heat loss of the facility are much lower than others. Clean air heated facility is adopted to conduct experiment, which is the first experiment of China in clean air inflow, research on hydrogen-fueled and ethylene-fueled ignition and combustion for scramjet combustor at different equivalence ratio. Successful ignition and sustained combustion of hydrogen has been achieved. Successful ethylene ignition and sustained main stream combustion is achieved with normal fuel injection and taking hydrogen as pilot flame. Experiment result shows that the wall pressure of combustor model rises when the equivalence ratio of hydrogen rises. As the wall pressure of combustor model rises, the pressure disturbance influences the shock train in the upstream.展开更多
Shaanxi province has three land forms which are Shaanxi’s northern plateau, Guanzhong plain and Qinba mountain land in the south of Shaanxi province. So the climate type is also divided into three types and the solar...Shaanxi province has three land forms which are Shaanxi’s northern plateau, Guanzhong plain and Qinba mountain land in the south of Shaanxi province. So the climate type is also divided into three types and the solar energy resources distribution has a big gap between different regions. PV modules, as the core component of off-grid home photovoltaic power system, their output power are mainly influenced by sun radiation, array tile angle, temperature and so on. Based on the reasons above, in order to apply off-grid home photovoltaic power system in Shaanxi region, this paper designs different systems with different configuration, and makes the performance prediction. The results show that the capacity of PV modules reaches to the largest in Shaanxi northern region, reach minimum in Shaanxi southern region and the output power in the winter is less than in the summer and reach minimum in the spring and autumn. In light of the characteristics above, this research select different type and configuration in different areas systematically, and the performance analysis shows that the configuration can meet the basic life demand of power to the people whose power is not available.展开更多
Because working performance of off-grid home photovoltaic power system is influenced by factors of solar radiation, ambient temperature and installation angle, this research established power supply model, analyzed wo...Because working performance of off-grid home photovoltaic power system is influenced by factors of solar radiation, ambient temperature and installation angle, this research established power supply model, analyzed working performance and optimized system configuration, by referencing weather conditions of Yulin and Yan’an and those factors. Results showed that under given solar radiation and ambient temperature, difference of installation angle can cause 30% to 40% difference of performance. In order to meet power demand, installation angles of Yulin and Yan'an were selected as 40 degree and 30 degree, and annual output power were 1.44 kWh/Wp and 1.32 kWh/Wp. Based on those results, the configuration of Yulin and Yan'an was 150 Wp and 170 Wp, and annual output power was 172.70 kWh and 179.66 kWh. Systems optimized above can meet the mid-scale demand in Shaanxi northern region and build theoretical foundation of application.展开更多
This study focuses on a single-stage axial flow fan, investigating the effect of three kinds of wave leading edge stator blades on its noise reduction. The DDES method and the duct acoustic analogy theory based on the...This study focuses on a single-stage axial flow fan, investigating the effect of three kinds of wave leading edge stator blades on its noise reduction. The DDES method and the duct acoustic analogy theory based on the penetrable data surface were used for noise prediction. The results showed that the three kinds of wave leading edge blades were effective in reducing the rotor-stator interaction tonal noise and also have a certain inhibitory effect on broadband noise. The A10W15 stator blade can effectively reduce broadband noise in the frequency range of 2200 - 4200 Hz. When the amplitude is increased to 20, the noise reduction effect is further enhanced. However, when the amplitude is increased to 30, the broadband noise reduction effect is no longer significant. Further research shows that the wave leading edge stator blades can significantly change the pressure fluctuation distribution on the leading edge and suction surface, which control the modal energy distribution. Finally, this paper analyzed multiple factors affecting the broadband noise reduction, such as the noise source cut-off and cut-on effect and correlation. The purpose of this paper is to explore the laws of the influence of wave leading edge blades on the duct noise of real fan, and to reveal its noise control mechanism. .展开更多
Base on the standard k-ωturbulent model,numerical method for solving three dimensional Reynolds Averaged Navier-Stokes(RANS)was adopted to study the aerothermal characteristics of the turbine blade with casing relati...Base on the standard k-ωturbulent model,numerical method for solving three dimensional Reynolds Averaged Navier-Stokes(RANS)was adopted to study the aerothermal characteristics of the turbine blade with casing relative motion.Experimental data were used to verify the effectiveness of the numerical method and turbulent model.The effect of blade tip clearance,geometry and relative motion on blade tip aerothermal characteristics were analyzed.The numerical results show that for the flat tip,relative motion can effectively suppress tip leakage and reduce leakage vortex size at rotating blade-static casing(BRCS)and static bladerotating casing(BSCR)conditions.A high level of heat transfer region can be observed near the leading edge at the conditions of rotating bladerotating casing(BRCS)and static bladestatic casing(BSCR).The blade tip heat transfer coefficient expands with the increase of tip clearance at different relative motion modes.At the brcs and bscs,the axial average heat transfer trend is the closest when the tip clearance is 1.5%H.The scraping vortex generated by relative motion at brcr and bscs inhib-its the development of leakage flow for squealer tip because of its sealing effect.High level of heat transfer region is also concentrated in the leading edge at brcr and bscs.The size of scraping vortex weakens with the increase of cavity depth.The distribution trend of the average heat transfer coefficient is similar in the two cases of relative static and relative motion,except for the case of 2.5%H cavity depth.展开更多
A gliding arc plasma fuel atomization actuator suitable for aeroengines was designed,and a gliding arc plasma fuel spray experimental platform was built to address the fuel atomization problem in aeroengine combustion...A gliding arc plasma fuel atomization actuator suitable for aeroengines was designed,and a gliding arc plasma fuel spray experimental platform was built to address the fuel atomization problem in aeroengine combustion chambers.The spray characteristics for different airflows,fuel flows,and discharge voltages were analyzed using laser particle size analysis.The research shows that the fuel atomization effect is improved from the increased airflow.The decreased fuel flow not only reduces the injection pressure of the fuel but also changes the discharge mode of the gliding arc,which affects reductions in the discharge power and inhibits fuel atomization.Gliding arc discharges accelerate the breaking,atomization,and evaporation of fuel droplets while reducing the particle size,which increases the proportion of small droplets.Compared with the working conditions of plasma-assisted atomization without the gliding arc,the D0.5,D0.9,and average particle size of the fuel droplets are reduced by 4.7%,6.5%,and 4.1%,respectively,when the modulation voltage of the gliding arc power supply is 200 V.展开更多
Based on the many-body radiative heat transfer theory,we investigate a thermal splitter based on three magneto-optical In Sb nanoparticles.The system comprises a source with adjustable parameters and two drains with f...Based on the many-body radiative heat transfer theory,we investigate a thermal splitter based on three magneto-optical In Sb nanoparticles.The system comprises a source with adjustable parameters and two drains with fixed parameters.By leveraging the temperature and magnetic field dependence of the permittivity of In Sb,the direction of heat flux in the system can be controlled by adjusting the magnetic field or temperature at the source.Under magnetic field control,the coupling between the separated modes,and the suppression of the zero-field mode induced by the magnetic field,are utilized to achieve a thermal splitting ratio within the modulation range of 0.15–0.58.Furthermore,temperature control results in a thermal splitting ratio ranging from 0.15 to 0.99,as a result of the suppression of the zero-field mode by the magnetic field and the blue shift effect of the zero-field mode frequency increasing with temperature.Notably,the gap distance between nanoparticles does not significantly affect the splitting ratio.These findings provide valuable theoretical guidance for utilizing magneto-optical nanoparticles as thermal splitters and lay the groundwork for implementing complex heat flux networks using In Sb for energy collection and heat transfer control.展开更多
文摘This paper presents the design and verification of the dual-mode core driven fan stage(CDFS)and high-load compressor with a large flow regulation range.In view of the characteristics of large flow regulation range of the two modes and high average stage load coefficient,this paper investigates the design technology of the dual-mode high-efficiency compressor with a large flow regulation range and high-load compressor with an average stage load coefficient of 0.504.Building upon this research,the design of the dual-mode CDFS and four-stage compressor is completed,and three-dimensional numerical simulation of the two modes is carried out.Finally,performance experiment is conducted to verify the result of three-dimensional numerical simulation.The experiment results show that the compressor performance is improved for the whole working conditions by using the new design method,which realizes the complete fusion design of the CDFS and high-pressure compressor(HPC).The matching mechanism of stage characteristics of single and double bypass modes and the variation rule of different adjustment angles on performance are studied comprehensively.Furthermore,it effectively reduces the length and weight of compressor,and breaks through the key technologies such as high-load compressor with the average load factor of 0.504.These findings provide valuable data and a methodological foundation for the development of the next generation aeroengine.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.52204258 and 52106099)the Postdoctoral Research Foundation of China (Grant No.2023M743779)+2 种基金the Fundamental Research Funds for the Central Universities (Grant No.2022QN1017)the Key Research Development Projects in Xinjiang Uygur Autonomous Region (Grant No.2022B03003-3)the Shandong Provincial Natural Science Foundation (Grant No.ZR2020LLZ004)。
文摘Anisotropic hyperbolic phonon polaritons(PhPs)in natural biaxial hyperbolic materialα-MoO_(3) has opened up new avenues for mid-infrared nanophotonics,while active tunability ofα-MoO_(3) PhPs is still an urgent problem necessarily to be solved.In this study,we present a theoretical demonstration of actively tuningα-MoO_(3) PhPs using phase change material VO_(2) and graphene.It is observed thatα-MoO_(3) PhPs are greatly dependent on the propagation plane angle of PhPs.The insulator-to-metal phase transition of VO_(2) has a significant effect on the hybridization PhPs of theα-MoO_(3)/VO_(2) structure and allows to obtain actively tunableα-MoO_(3) PhPs,which is especially obvious when the propagation plane angle of PhPs is 900.Moreover,when graphene surface plasmon sources are placed at the top or bottom ofα-MoO_(3) inα-MoO_(3)/VO_(2)structure,tunable coupled hyperbolic plasmon-phonon polaritons inside its Reststrahlen bands(RB s)and surface plasmonphonon polaritons outside its RBs can be achieved.In addition,the above-mentionedα-MoO_(3)-based structures also lead to actively tunable anisotropic spontaneous emission(SE)enhancement.This study may be beneficial for realization of active tunability of both PhPs and SE ofα-MoO_(3),and facilitate a deeper understanding of the mechanisms of anisotropic light-matter interaction inα-MoO_(3) using functional materials.
基金supported by Major Science and Technology Project of Sichuan Province[No.2022YFG0315,2022YFG0174]Sichuan Gas Turbine Research Institute stability support project of China Aero Engine Group Co.,Ltd[GJCZ-2019-59]Key project of Chengdu[No.2019-YF09-00044-CG].
文摘The further development of catalytic elements has been plagued by activation and binary problems.The automatic shift model that has emerged in recent years helps components achieve full range.However,the detection data still remains unstable in the shift area(7%∼13%).This paper proposes a Catalytic Combustion and Thermal Conductivity(CCTC)model for the specified range,which can be explained fromtwo aspects based on the existing methods.On the one hand,it uses iterative location search to process heterogeneous data,judges the prediction position of data points,and then givesweight evaluation.On the other hand,it corrects the abnormal points,determines the abnormal points in the horizontal direction,and gives the replacement value through the data of adjacent points.The experimental results show that the CCTC model reduces the sum of variance from 17 of the automatic shift model to 13,and the comparison of experimental variance is reduced by 23%.In the full-scale real-time data,the experimental variance of CCTC model and automatic shift model is reduced by 18%.In conclusion,CCTC is a cross section stability framework for full-scale methane measurement,in which the specified heterogeneous combination and anomaly point correction methods improve the stability.
基金using the equipment of the Research Educational Center“REC-Vibration Strengthand Reliability of Aerospace Products”with financial support from the Ministry of Science and Higher Education of the Russian Federation(Project No FSSS-2024-0017).
文摘This article presents a device for the storage and gasification of cryogenic working fluid,which is named a cryogenic fuelling tank.A cryogenic fuel tank can serve both as a fuel vessel and a pressure accumulator due to the regasification process that takes place inside.Application of this tank is slowed by the lack of theoretical and experimental research on its working process.This article deals with an investigation of the working process of the energy plant based on a cryogenic fuel tank coupled with a rotor-vane expander.Developed mathematical models include evaporation and condensation processes within the tank,heat exchange between gas chambers and between the tank and environment,and changes in energy due to incoming and leaving mass.Mechanical work used to determine the efficiency of a power plant is generated by a steam expander.Research shows that it is possible to achieve specific work outputs up to 110-160 kJ/kg with relative deviation of power and specific work determination equal to 1.4% and 1.9%correspondingly.
基金Project supported by the National Natural Science Foundation of China (Grant No.52106099)the Natural Science Foundation of Shandong Province of China (Grant No.ZR2022YQ57)the Taishan Scholars Program。
文摘Relative rotation between the emitter and receiver could effectively modulate the near-field radiative heat transfer(NFRHT)in anisotropic media.Due to the strong in-plane anisotropy,natural hyperbolic materials can be used to construct near-field radiative modulators with excellent modulation effects.However,in practical applications,natural hyperbolic materials need to be deposited on the substrate,and the influence of substrate on modulation effect has not been studied yet.In this work,we investigate the influence of substrate effect on near-field radiative modulator based onα-MoO_(3).The results show that compared to the situation without a substrate,the presence of both lossless and lossy substrate will reduce the modulation contrast(MC)for different film thicknesses.When the real or imaginary component of the substrate permittivity increases,the mismatch of hyperbolic phonon polaritons(HPPs)weakens,resulting in a reduction in MC.By reducing the real and imaginary components of substrate permittivity,the MC can be significantly improved,reaching 4.64 forε_(s)=3 at t=10 nm.This work indicates that choosing a substrate with a smaller permittivity helps to achieve a better modulation effect,and provides guidance for the application of natural hyperbolic materials in the near-field radiative modulator.
基金financially supported by the National Natural Science Foundation of China through Grant Nos.12372338 and U2241272the Natural Science Foundation of Shaanxi Province of China through Grant Nos.2023-JC-YB-352 and 2022JZ-20+1 种基金the Guangdong Basic and Applied Basic Research Foundation through Grant No.2023A1515011663the Practice and Innovation Funds for Graduate Students of Northwestern Polytechnical University through Grant No.PF2023010。
文摘Due to the strong unsteadiness of pulse detonation,large flow losses are generated when the detonation wave interacts with the turbine blades,resulting in low turbine efficiency.Considering that the flow losses are dissipated into the gas as heat energy,some of them can be recycled during the expansion process in subsequent stages by the reheat effect,which should be helpful to improve the detonationdriven turbine efficiency.Taking this into account,this paper developed a numerical model of the detonation chamber coupled with a two-stage axial turbine,and a stoichiometric hydrogen-air mixture was used.The improvement in turbine efficiency attributable to the reheat effect was calculated by comparing the average efficiency of the stages with the efficiency of the two-stage turbine.The research indicated that the first stage was critical in suppressing the flow unsteadiness caused by pulse detonation,which stabilized the intake condition of the second stage and consequently allowed much of the flow losses from the first stage to be recycled,so that the efficiency of the two-stage turbine was improved.At a 95%confidence level,the efficiency improvement was stable at 4.5%—5.3%,demonstrating that the reheat effect is significant in improving the efficiency of the detonation-driven turbine.
基金National Natural Science Foundation of China(51976172)National Science and Technology Major Project (2017-II-0009-0023)+1 种基金China’s 111 project(B17037)Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX2023056)。
文摘The time domain harmonic balance method is an attractive reduced order method of analyzing unsteady flow for turbomachines. However, the method can admit non-physical solutions. Non-physical solutions were encountered from a three-blade-row compressor configuration in a time domain harmonic balance analysis. This paper aims to investigate the root cause of the non-physical solutions. The investigation involves several strategies, which include increasing the number of harmonics, increasing the number of time instants, including scattered modes,including the rotor-rotor interaction, and the use of a new method-the approximate time domain nonlinear harmonic method. Numerical analyses pertinent to each strategy are presented to reveal the root cause of the non-physical solution. It is found that the nonlinear interaction of unsteady flow components with different fundamental frequencies is the cause of the non-physical solution. The non-physical solution can be eliminated by incorporating extra scattered modes or using the approximate time domain nonlinear harmonic method.
基金supported by the National Natural Science Foundation of China(No.51405393)
文摘The elastic support/dry friction damper is a type of damper which is used for active vibration control in a rotor system.To establish the analytical model of this type of damper,a two-dimensional friction model-ball/plate model was proposed.By using this ball/plate model,a dynamics model of rotor with elastic support/dry friction dampers was established and experimentally verified.Moreover,the damping performance of the elastic support/dry friction damper was studied numerically with respect to some variable parameters.The numerical study shows that the damping performance of the elastic support/dry friction damper is closely related to the stiffness distribution of the rotor-support system,the damper location,the pressing force between the moving and stationary disk,the friction coefficient,the tangential contact stiffness of the contact interface,and the stiffness of the stationary disk.In general,the damper should be located on an elastic support which has a large vibration amplitude in order to achieve a better damping performance,and the more vibration energy in this elastic support concentrates,the better performance of the damper will be.The larger the tangential contact stiffness of the contact interface,and the stiffness of the stationary disk are,the better performance of the damper will be.There will be an optimal value of the friction force at which the damper performs best.
基金Project(11174065)supported by the National Natural Science Foundation of China
文摘The multi-dimensional time-domain computational fluid dynamics(CFD) approach is extended to calculate the acoustic attenuation performance of water-filled piping silencers. Transmission loss predictions from the time-domain CFD approach and the frequency-domain finite element method(FEM) agree well with each other for the dual expansion chamber silencer, straight-through and cross-flow perforated tube silencers without flow. Then, the time-domain CFD approach is used to investigate the effect of flow on the acoustic attenuation characteristics of perforated tube silencers. The numerical predictions demonstrate that the mean flow increases the transmission loss, especially at higher frequencies, and shifts the transmission loss curve to lower frequencies.
基金supported by the National Natural Science Foundation of China (Nos. 10772147 and10632030)the Ph. D. Program Foundation of Ministry of Education of China (No. 20070699028)+2 种基金the Natural Science Foundation of Shaanxi Province of China (No. 2006A07)the Open Foundationof State Key Laboratory of Structural Analysis of Industrial Equipment (No. GZ0802)the Foundation for Fundamental Research of Northwestern Polytechnical University
文摘Nonlinear wave equations have been extensively investigated in the last sev- eral decades. The Landau-Ginzburg-Higgs equation, a typical nonlinear wave equation, is studied in this paper based on the multi-symplectic theory in the Hamilton space. The multi-symplectic Runge-Kutta method is reviewed, and a semi-implicit scheme with certain discrete conservation laws is constructed to solve the first-order partial differential equations （PDEs） derived from the Landau-Ginzburg-Higgs equation. The numerical re- sults for the soliton solution of the Landau-Ginzburg-Higgs equation are reported, showing that the multi-symplectic Runge-Kutta method is an efficient algorithm with excellent long-time numerical behaviors.
基金Supported by National Natural Science Foundation of China(Grant Nos.51976173,51976014)Jiangsu Provincial Natural Science Foundation of China(Grant No.BK20201204)Basic Research Program of Taicang(Grant No.TC2019JC01).
文摘With the development of modern technology and economy,environmental protection and sustainable development have become the focus of global attention.The promotion and development of electric vehicles(EVs)have bright prospects.However,many challenges need to be faced seriously.Under diferent operating conditions,various safety problems of electric vehicles emerge one after another,especially the hidden danger of battery overheating which threatens the performance of electric vehicles.This paper aims to design and optimize a new indirect liquid cooling system for cylindrical lithium-ion batteries.Various design schemes for diferent cooling channel structures and cooling liquid inlet directions are proposed,and the corresponding solid-fuid coupling model is established.COMSOL Multiphysics simulation software is adopted to simulate and analyze the cooling systems.An approximate model is constructed using the Kriging method,which is considered to optimize the battery cooling system and improve the optimization results.Sensitivity parameter analysis and the optimization design of system structure are performed through a set of infuencing factors in the battery thermal management.The results indicate that the method used in this paper can efectively reduce the maximum core temperature and balance the temperature diferences of the battery pack.Compared with the original design,the optimized design,which is based on the non-dominated sorting genetic algorithm(NSGA-II),has an excellent ability in the optimized thermal management system to dissipate thermal energy and keep the overall cooling uniformity of the battery and thermal management system.Furthermore,the optimized system can also prevent thermal runaway propagation under thermal abuse conditions.In summary,this research can provide some practical suggestions and ideas for the engineering and production applications and structural optimization design carried by electric vehicles.
文摘A PID parameters tuning and optimization method for a turbine engine based on the simplex search method was proposed. Taking time delay of combustion and actuator into account, a simulation model of a PID control system for a turbine engine was developed. A performance index based on the integral of absolute error （IAE） was given as an objective function of optimization. In order to avoid the sensitivity that resulted from the initial values of the simplex search method, the traditional Ziegler-Nichols method was used to tune PID parameters to obtain the initial values at first, then the simplex search method was applied to optimize PID parameters for the turbine engine. Simulation results indicate that the simplex search method is a reasonable and effective method for PID controller parameters tuning and optimization.
基金Supported by the National Natural Science Foundation of China under Grant No 91441201
文摘Highly efficient and stable hybrid white organic light-emitting diodes （HWOLEDs） with a mixed bipolar interlayer between fluorescent blue and phosphorescent yellow emitting layers are demonstrated. The bipolar interlayer is a mixture of p-type diphenyl （l0-phenyl-lOH-spiro [acridine-9,9＇-fluoren]-3Lyl） phosphine oxide and n-type 2＇,2- （1,3,5-benzinetriyl）-tris（1-phenyl-l-H-benzimidazole）. The electroluminance and Commission Internationale de l＇Eclairage （CIE1931） coordinates＇ characteristics can be modulated easily by adjusting the ratio of the hole- predominated material to the electron-predominated material in the interlayer. The hybrid WOLED with a p-type：n-type ratio of 1：3 shows a maximum current efficiency and power efficiency of 61.1 ed/A and 55.8 lm/W, respectively, with warm white CIE coordinates of （0.34, 0.43）. The excellent efficiency and adaptive CIE coordi- nates are attributed to the mixed interlayer with improved charge carrier balance, optimized exciton distribution, and enhanced harvesting of singlet and triplet excitons.
基金supported by National Hi-tech Research and Development Program of China (863 Program, Grant No. 2003AA723072)
文摘The scramjet, which is the propulsion of hypersonic vehicle, has become the focus in many military developed countries. The ground tests play an important role in the research of scramjet. There is defect of test medium contamination （the thermochemical characteristic of the ground test medium is different from that of the flight medium） in existing ground test facilities for scramjet combustor experiment. To solve the problem of test medium contamination, the first clean air heated facility of China for scramjet combustor experiment is designed. The key technology of designing the clean air heated facility is summarized. By using bypass duct, combustor model is protected from high temperature. To reduce the switching time between main duct and bypass duct, solenoid valve and water-cooled system were used. Having centrosymmetric structure, the heat radiating area of the facility and heat loss of the facility are much lower than others. Clean air heated facility is adopted to conduct experiment, which is the first experiment of China in clean air inflow, research on hydrogen-fueled and ethylene-fueled ignition and combustion for scramjet combustor at different equivalence ratio. Successful ignition and sustained combustion of hydrogen has been achieved. Successful ethylene ignition and sustained main stream combustion is achieved with normal fuel injection and taking hydrogen as pilot flame. Experiment result shows that the wall pressure of combustor model rises when the equivalence ratio of hydrogen rises. As the wall pressure of combustor model rises, the pressure disturbance influences the shock train in the upstream.
文摘Shaanxi province has three land forms which are Shaanxi’s northern plateau, Guanzhong plain and Qinba mountain land in the south of Shaanxi province. So the climate type is also divided into three types and the solar energy resources distribution has a big gap between different regions. PV modules, as the core component of off-grid home photovoltaic power system, their output power are mainly influenced by sun radiation, array tile angle, temperature and so on. Based on the reasons above, in order to apply off-grid home photovoltaic power system in Shaanxi region, this paper designs different systems with different configuration, and makes the performance prediction. The results show that the capacity of PV modules reaches to the largest in Shaanxi northern region, reach minimum in Shaanxi southern region and the output power in the winter is less than in the summer and reach minimum in the spring and autumn. In light of the characteristics above, this research select different type and configuration in different areas systematically, and the performance analysis shows that the configuration can meet the basic life demand of power to the people whose power is not available.
文摘Because working performance of off-grid home photovoltaic power system is influenced by factors of solar radiation, ambient temperature and installation angle, this research established power supply model, analyzed working performance and optimized system configuration, by referencing weather conditions of Yulin and Yan’an and those factors. Results showed that under given solar radiation and ambient temperature, difference of installation angle can cause 30% to 40% difference of performance. In order to meet power demand, installation angles of Yulin and Yan'an were selected as 40 degree and 30 degree, and annual output power were 1.44 kWh/Wp and 1.32 kWh/Wp. Based on those results, the configuration of Yulin and Yan'an was 150 Wp and 170 Wp, and annual output power was 172.70 kWh and 179.66 kWh. Systems optimized above can meet the mid-scale demand in Shaanxi northern region and build theoretical foundation of application.
文摘This study focuses on a single-stage axial flow fan, investigating the effect of three kinds of wave leading edge stator blades on its noise reduction. The DDES method and the duct acoustic analogy theory based on the penetrable data surface were used for noise prediction. The results showed that the three kinds of wave leading edge blades were effective in reducing the rotor-stator interaction tonal noise and also have a certain inhibitory effect on broadband noise. The A10W15 stator blade can effectively reduce broadband noise in the frequency range of 2200 - 4200 Hz. When the amplitude is increased to 20, the noise reduction effect is further enhanced. However, when the amplitude is increased to 30, the broadband noise reduction effect is no longer significant. Further research shows that the wave leading edge stator blades can significantly change the pressure fluctuation distribution on the leading edge and suction surface, which control the modal energy distribution. Finally, this paper analyzed multiple factors affecting the broadband noise reduction, such as the noise source cut-off and cut-on effect and correlation. The purpose of this paper is to explore the laws of the influence of wave leading edge blades on the duct noise of real fan, and to reveal its noise control mechanism. .
基金National Natural Science Foundation of China(No.52006178)National Key R&D Program of China(No.Y2019-Ⅷ-0007-0168)the Fundamental Research Funds for the Central Universities and the Innovation Capacity Support Plan in Shaanxi Province of China(Grant No.2023-CX-TD-19)。
文摘Base on the standard k-ωturbulent model,numerical method for solving three dimensional Reynolds Averaged Navier-Stokes(RANS)was adopted to study the aerothermal characteristics of the turbine blade with casing relative motion.Experimental data were used to verify the effectiveness of the numerical method and turbulent model.The effect of blade tip clearance,geometry and relative motion on blade tip aerothermal characteristics were analyzed.The numerical results show that for the flat tip,relative motion can effectively suppress tip leakage and reduce leakage vortex size at rotating blade-static casing(BRCS)and static bladerotating casing(BSCR)conditions.A high level of heat transfer region can be observed near the leading edge at the conditions of rotating bladerotating casing(BRCS)and static bladestatic casing(BSCR).The blade tip heat transfer coefficient expands with the increase of tip clearance at different relative motion modes.At the brcs and bscs,the axial average heat transfer trend is the closest when the tip clearance is 1.5%H.The scraping vortex generated by relative motion at brcr and bscs inhib-its the development of leakage flow for squealer tip because of its sealing effect.High level of heat transfer region is also concentrated in the leading edge at brcr and bscs.The size of scraping vortex weakens with the increase of cavity depth.The distribution trend of the average heat transfer coefficient is similar in the two cases of relative static and relative motion,except for the case of 2.5%H cavity depth.
基金supported by National Natural Science Foundation of China(Nos.91741112 and 52276142)。
文摘A gliding arc plasma fuel atomization actuator suitable for aeroengines was designed,and a gliding arc plasma fuel spray experimental platform was built to address the fuel atomization problem in aeroengine combustion chambers.The spray characteristics for different airflows,fuel flows,and discharge voltages were analyzed using laser particle size analysis.The research shows that the fuel atomization effect is improved from the increased airflow.The decreased fuel flow not only reduces the injection pressure of the fuel but also changes the discharge mode of the gliding arc,which affects reductions in the discharge power and inhibits fuel atomization.Gliding arc discharges accelerate the breaking,atomization,and evaporation of fuel droplets while reducing the particle size,which increases the proportion of small droplets.Compared with the working conditions of plasma-assisted atomization without the gliding arc,the D0.5,D0.9,and average particle size of the fuel droplets are reduced by 4.7%,6.5%,and 4.1%,respectively,when the modulation voltage of the gliding arc power supply is 200 V.
基金supported by the National Natural Science Foundation of China(Grant Nos.92050104,12274314,12174281,and 52106099)the Natural Science Foundation of Jiangsu Province(Grant No.BK20221240)+1 种基金the Natural Science Foundation of Shandong Province(Grant No.ZR2022YQ57)the Taishan Scholars Program。
文摘Based on the many-body radiative heat transfer theory,we investigate a thermal splitter based on three magneto-optical In Sb nanoparticles.The system comprises a source with adjustable parameters and two drains with fixed parameters.By leveraging the temperature and magnetic field dependence of the permittivity of In Sb,the direction of heat flux in the system can be controlled by adjusting the magnetic field or temperature at the source.Under magnetic field control,the coupling between the separated modes,and the suppression of the zero-field mode induced by the magnetic field,are utilized to achieve a thermal splitting ratio within the modulation range of 0.15–0.58.Furthermore,temperature control results in a thermal splitting ratio ranging from 0.15 to 0.99,as a result of the suppression of the zero-field mode by the magnetic field and the blue shift effect of the zero-field mode frequency increasing with temperature.Notably,the gap distance between nanoparticles does not significantly affect the splitting ratio.These findings provide valuable theoretical guidance for utilizing magneto-optical nanoparticles as thermal splitters and lay the groundwork for implementing complex heat flux networks using In Sb for energy collection and heat transfer control.
