The stator of the maglev track plays a crucial role in the operation of the maglev system.Currently,the efficiency of maglev track inspection is limited by several factors,including the large span of elevated structur...The stator of the maglev track plays a crucial role in the operation of the maglev system.Currently,the efficiency of maglev track inspection is limited by several factors,including the large span of elevated structures,manual visual inspection,short inspection window times,and limited GPS positioning accuracy.To address these issues,this paper proposes a deep learning-based method for detecting and locating stator surface damage.This study establishes a maglev track stator surface image dataset,trains different object detection models,and compares their performance.Ultimately,YOLO and ByteTrack object tracking algorithms were chosen as the basic framework and enhanced to achieve automatic identification of high-speed maglev track stator surface damage images and track and count stator surface localization feature images.By matching the identified damaged images with their corresponding stator segment and beam segment sequence numbers,the location of the damage is pinpointed to the corresponding stator segment,enabling rapid and accurate identification and localization of complex damage to the maglev track stator surface.展开更多
High-speed maglev trains(HSMTs)can run at high running speeds due to their unique design.The pressure waves that these trains generate while passing each other are therefore very intense,and can even have safety impli...High-speed maglev trains(HSMTs)can run at high running speeds due to their unique design.The pressure waves that these trains generate while passing each other are therefore very intense,and can even have safety implications.In order to reduce the transient impact of such waves,the standard k-ε turbulence model is used in this work to assess the effect of railway spacing on the aerodynamic loads,pressure and surrounding flow field of 600 km/h maglev trains passing each other in open air.The sliding mesh technique is used to determine the relative motion between the considered trains.The results show that the surface pressure is approximately linearly correlated with the square of the speed while the amplitude of the pressure wave on the train surface,side force,and rolling moment all have negative exponential relationships with the railway spacing.展开更多
To address the severe aerodynamic effects caused by a 600 km/h superconducting maglev train passing through a tunnel at full speed,this study systematically investigates the coupled influence of auxiliary facility par...To address the severe aerodynamic effects caused by a 600 km/h superconducting maglev train passing through a tunnel at full speed,this study systematically investigates the coupled influence of auxiliary facility parameters including the shaft(location L,cross sectional dimension W,height h),tunnel portal(cross sectional area S),and openings(spacing D,side length F)on the evolution of tunnel aerodynamic effects.By integrating three dimensional unsteady flow field numerical simulations with a dynamic model testing system,the research notably reveals the regulatory mechanisms of these parameters on the evolution characteristics of the initial compression wave pressure gradient and the multi peak structure of micro-pressure waves.The results show that shaft parameters significantly affect the initial compression wave.Both the wave amplitude and gradient exhibit a linear negative correlation with cross sectional dimension W and a linear positive correlation with location L,while demonstrating a nonlinear relationship with height h,the amplitude follows a cubic polynomial trend,and the gradient initially increases before plateauing.Under the configuration W=8 m,L=50 m,and h=20 m,substantial reductions in both compression wave amplitude and gradient were achieved.The portal cross sectional area S shows a"U-shaped"relationship with the compression wave gradient,with the maximum gradient reduction of 53.24%occurring at S=210 m^(2),a result comparable to that achieved with optimized opening parameters(D=15 m,F=3.5 m,53.96%).Regarding micro-pressure waves,the amplitude measured 20 m from the tunnel exit shows a linear positive correlation with shaft parameters L and W,while the influence of h saturates beyond 50 m.Reductions exceeding 54%were achieved with portal parameters,either at S=210 m^(2) or using the optimized opening configuration.Furthermore,micro-pressure waves near the portal exhibit a consistent dual peak structure:the first peak originates from the train entry compression wave,and the second results from further wave compression after tunnel exit.The opening location governs selective peak regulation openings near the portal entrance primarily suppress the first peak with minimal impact on the second,whereas centrally located openings reduce the first peak but can amplify the second by up to 3%.Based on these insights,an optimized parameter configuration is proposed:a shaft with a cross-sectional dimension≥8 m located 50 m from the portal,a portal cross sectional area of 210 m^(2),and openings spaced at 15 m intervals.This configuration can reduce the initial compression wave gradient by over 50%.The results provide a theoretical foundation for controlling aerodynamic effects of superconducting maglev train.展开更多
A ground girder is laid on the preprocessed subgrade by gravity compaction and integrally uniformly supported by subgrade in maglev transit.The settlement of the maglev subgrade inevitably affects the vibration state ...A ground girder is laid on the preprocessed subgrade by gravity compaction and integrally uniformly supported by subgrade in maglev transit.The settlement of the maglev subgrade inevitably affects the vibration state of the medium and low speed maglev coupled system by the additional deformation of the maglev track.This study investigated the dynamic properties of the coupled vibration system affected by the subgrade settlement.First,a theoretical coupled vibration model of a maglev train-track-ground girder system with uneven subgrade settlement was proposed and verified.Then,the effect mechanism of the coupled system caused by the uneven subgrade settlement was explored.Finally,settlement types and subgrade support voiding were examined.The analysis showed that the uneven subgrade settlement considerably increased the dynamic responses of the levitation control system and maglev vehicle while having a minor influence on those of the track-ground girder.The influence of a single ground girder settling was the strongest,and adjacent sides’settling of two ground girders was the weakest for the vibration of a maglev train.An extremely large uneven settlement exceeding 6 mm led to active levitation control system instability.The subgrade support voiding enlarged the vehicle-induced vibration of the track ground girder.展开更多
Maglev trains experience significant aerodynamic effects when passing through tunnels.A moving model test was conducted to explore the practical effects of speed reduction and entrance buffer structures on mitigating ...Maglev trains experience significant aerodynamic effects when passing through tunnels.A moving model test was conducted to explore the practical effects of speed reduction and entrance buffer structures on mitigating tunnel/maglev aerodynamic effects.It is found that both have an overall positive effect on mitigating the aerodynamic environment inside and outside the tunnel.Trains operating at 200 km/h show a 49.8%decrease in peak-to-peak pressure and a 50.7%decrease in transient pressure instability on inner walls compared to those at 280 km/h.Lower speeds resulted in a 65.6%decrease in amplitude and a 24.5%decrease in decay rate,both of which are parameters for exponential fittings of pressure peaks that decay naturally after the train leaves.The buffer structures result in a reduction of up to 25.7%in the maximum positive pressure and a 29.0%decrease in transient pressure instability.Additionally,a reduction in amplitude of up to 21.2%and a 32.2%increase in decay rate were observed with the use of buffer structures.Nevertheless,it is difficult to conclude direct correlations between the maximum pressure,peak-to-peak values,etc.,and the speeds or buffer structures due to the complex wave propagation in tunnels.However,speed reduction and buffer structures are proven to be effective in reducing the micro-pressure wave levels with a simpler monotonic relationship.展开更多
Currently,the design of high-temperature superconducting(HTS)maglev trains adopts a U-shaped track operation mode,and the height of the side track significantly impacts the train’s aerodynamic characteristics.In this...Currently,the design of high-temperature superconducting(HTS)maglev trains adopts a U-shaped track operation mode,and the height of the side track significantly impacts the train’s aerodynamic characteristics.In this study,we used computational fluid dynamics(CFD)methods,based on the 3D Reynolds-averaged Navier-Stokes(RANS)method and shear stress transport(SST)k-ωturbulence model,to deeply investigate the effects of the presence or absence of a U-shaped track and different side track heights(800,880,and 960 mm)on the pressure distribution,velocity distribution,and flow field structure of HTS maglev trains at a speed of 400 km/h under crosswinds.The numerical methods were verified using a scaled ICE-2 model wind tunnel test.First,the aerodynamic characteristics of the train under different wind direction angles with and without side tracks were studied.We found that the aerodynamic performance of the train is the most adverse when the wind direction angle is 90°.The presence of a U-shaped track can effectively reduce the lateral force,lift,and yawing moment of the train.The aerodynamic performance of the first suspension bogie at the bottom,which is the worst,will also be effectively improved.Next,the aerodynamic effects of different side track heights on the HTS maglev train were studied.An increase in side track height will reduce the lift and lateral force of the train,while the increase in drag is relatively small.Under the premise of ensuring passengers can conveniently alight,we found that a U-shaped track with a side track height of 960 mm has the best aerodynamic performance.The research findings offer a valuable reference for the engineering application and design of the track structure of HTS maglev train systems.展开更多
The suspension gap is a critical operational parameter for high-speed maglev trains and significantly impacts their aerodynamic performance.Based on an engineering prototype of the high-temperature superconducting(HTS...The suspension gap is a critical operational parameter for high-speed maglev trains and significantly impacts their aerodynamic performance.Based on an engineering prototype of the high-temperature superconducting(HTS)pinning maglev train,this study established a detailed three-dimensional model,and then the aerodynamic characteristics of the HTS maglev train at 600 km/h with suspension gaps of 10 mm,20 mm,and 30 mm were simulated based on the improved delayed detached eddy simulation(IDDES)turbulence model and SST kωtwo-equation.The results demonstrated that the underbody design of the HTS maglev train leads to unique aerodynamic drag and aerothermal distribution phenomena.The head car experiences the smallest drag,while the tail car experiences the largest.The aerothermal temperature on the train's bottom surface progressively increases from the head to the tail.Additionally,the U-shaped track significantly constrains the flow around the train body,forming strong vortex structures.As the suspension gap increases from 10 mm to 30 mm,the airflow velocity in the train-track gap rises,reducing the underbody pressure and decreasing the lift of the head car by 12.43%.The drag of the head car increases by 10.98%,primarily due to changes in pressure drag.Additionally,the temperature at the underbody of the tail car rises further due to significant airflow deceleration.These findings provide valuable insights for advancing the engineering design and application of the high-speed HTS maglev technology.展开更多
Evacuated tube transportation(ETT)offers a promising high-speed transport solution,but trains operating at supersonic speeds within a sealed tube can induce complex aerodynamic phenomena that impact safety and reliabi...Evacuated tube transportation(ETT)offers a promising high-speed transport solution,but trains operating at supersonic speeds within a sealed tube can induce complex aerodynamic phenomena that impact safety and reliability.This study utilized the Reynolds-averaged Navier-Stokes(RANS)shear stress transport k-ω(SST k-ω)turbulence model for steady-state simulations and the improved delayed detached eddy simulation(IDDES)SST k-ωmodel for unsteady state simulations,both coupled with the advection upstream splitting method(AUSM).Four tunnel cross-sectional areas(49 m^(2),64 m^(2),81 m^(2),and 100 m^(2))with corresponding blockage ratios(β)(0.253,0.192,0.150,0.121)were analyzed to explore shock wave formation and its dependence on blockage ratios,along with surface pressure distribution and aerodynamic loading.Results show that higher blockage ratios increase shock wave intensity,while larger tunnel areas reduce this intensity,improving flow structure and wake effects.Moreover,as the blockage ratio decreases,the total drag coefficient of the entire train decreases linearly.When the blockage ratio decreases from 0.253 to 0.121,the total drag coefficient of the entire train decreases by 46.2%,with the head carriage and tail carriage drag coefficients decreasing by 23.3%and 32.7%,respectively,while the drag coefficient of the middle carriage remains nearly unchanged.The percentage of the total drag coefficient contributed by the head carriage decreases from 51.1%to 40.9%,while the percentage for the tail carriage increases from 47.0%to 56.6%.These findings enhance understanding of ETT fluid dynamics and performance.展开更多
The increasing aerodynamic noise caused by high-speed maglev trains(HSMTs)contributes substantially to environmental pollution and passenger discomfort.Numerical studies were performed to examine the effect of air blo...The increasing aerodynamic noise caused by high-speed maglev trains(HSMTs)contributes substantially to environmental pollution and passenger discomfort.Numerical studies were performed to examine the effect of air blowing/sucking modes,positions and velocities on the flow field change and their potentials in mitigating the aerodynamic noise produced by HSMTs.The results indicate that the aerodynamic noise can be effectively mitigated by implementing air-blowing in the transition region between the streamlined tail nose and constant cross-sectional body(Scheme 1)and the wake vortex shedding area near the tail nose(Scheme 3)at speeds below 0.3 U(train speed),as well as in the side edge area(Scheme 2)at various speeds(0.1 U-0.5 U),primarily due to the suppression in wake vortices.The optimal noise reduction value of 1.53 dB(A)is achieved when blowing in Scheme 1 at a speed of 0.1 U,while the efficacy of the air-sucking mode is inferior with a smaller noise reduction value less than 0.84 dB(A).Additionally,simultaneous reductions in aerodynamic noise and drag can be achieved when sucking in Scheme 2 at speeds below 0.2 U and blowing in Scheme 3 at speeds below 0.3 U.These findings offer valuable insights for the application of active flow control technology in the design of low-resistance and low-noise HSMTs.展开更多
High-speed maglev trains represent a key direction for the future development of rail transportation.As operating speeds increase,they face increasingly severe aerodynamic challenges.The streamlined aerodynamic shape ...High-speed maglev trains represent a key direction for the future development of rail transportation.As operating speeds increase,they face increasingly severe aerodynamic challenges.The streamlined aerodynamic shape of a maglev train is a critical factor influencing its aerodynamic performance,and optimizing its length plays a significant role in improving the overall aerodynamic characteristics of the train.In this study,a numerical simulation model of a high-speed maglev train was established based on computational fluid dynamics(CFD)to investigate the effects of streamline length on the aerodynamic performance of the train operating on an open track.The results show that the length of the streamlined section has a pronounced impact on aerodynamic performance.When the streamline length increases from 8.3 to 14.3 m,the aerodynamic drag of the head and tail cars decreases by 16.2%and 32.1%,respectively,with reductions observed in both frictions drag and pressure drag-the latter showing the most significant decrease in the tail car.Moreover,the extended streamline length effectively suppresses flow separation on the train body surface.The intensity of the positive pressure region on the upper surface of the head car streamlined section is reduced,directly leading to a 38.2%reduction in lift.This research provides a theoretical basis for the parametric design of aerodynamic shapes for high-speed maglev trains and offers guidance and recommendations for drag and lift reduction optimization.展开更多
A high-speed train travelling from the open air into a narrow tunnel will cause the“sonic boom”at tunnel exit.When the maglev train’s speed reaches 600 km/h,the train-tunnel aerodynamic effect is intensified,so a n...A high-speed train travelling from the open air into a narrow tunnel will cause the“sonic boom”at tunnel exit.When the maglev train’s speed reaches 600 km/h,the train-tunnel aerodynamic effect is intensified,so a new mitigation method is urgently expected to be explored.This study proposed a novel asymptotic linear method(ALM)for micro pressure wave(MPW)mitigation to achieve a constant gradient of initial c ompression waves(ICWs),via a study with various open ratios on hoods.The properties of ICWs and MPWs under various open ratios of hoods were analyzed.The results show that as the open ratio increases,the MPW amplitude at the tunnel exit initially decreases before rising.At the open ratio of 2.28%,the slope of the ICW curve is linearly coincident with a supposed straight line in the ALM,which further reduces the MPW amplitude by 26.9%at 20 m and 20.0%at 50 m from the exit,as compared to the unvented hood.Therefore,the proposed method effectively mitigates MPW and quickly determines the upper limit of alleviation for the MPW amplitude at a fixed train-tunnel operation condition.All achievements provide a ne w potential measure for the adaptive design of tunnel hoods.展开更多
The risk of failure of the control loop can occur when a high-speed maglev train runs on viaduct.Meanwhile,the failure of the levitation magnets which balances the gravity of the maglev train could cause the train col...The risk of failure of the control loop can occur when a high-speed maglev train runs on viaduct.Meanwhile,the failure of the levitation magnets which balances the gravity of the maglev train could cause the train collision with track.To study the dynamic response of the train and the viaduct when the levitation magnet control loop failure occurs,a high-speed maglev train-viaduct coupling model,which includes a maglev controller fitted by measured force-gap data and considers the actual structure of train and viaduct,is established.Then the accuracy and effectiveness of the established approach are validated by comparing the computed dynamic responses and frequencies with the measurement results.After that,the dynamic responses of maglev train and viaduct are discussed under normal operation and control loop failures,and the most disadvantageous combination of control loop failures is obtained.The results show that when a single control loop fails,it only has a great influence on the failed electromagnet,and the maglev response of adjacent electromagnets has no obvious change and no collision occurs.But there is a risk of rail collisions when the dual control loop fails.展开更多
The dynamic interaction between the maglev vehicle and the three-span rigid frame bridge is discussed. With the consideration of magnetic force, the interaction model is developed. Numerical simulations are performed ...The dynamic interaction between the maglev vehicle and the three-span rigid frame bridge is discussed. With the consideration of magnetic force, the interaction model is developed. Numerical simulations are performed to study the dynamic characteristics of the bridge during vehicle movement along the bridge. The results show that a reasonable value of the linear stiffness ratio of columns to beams is between 2. 0 and 3.0. The dynamic responses of the bridge are aggravated with the decrease in bending rigidity and the increase in vehicle speed and the span ratio of the bridge. It is suggested that a definite way is to control impact coefficients and acceleration in the dynamic design of the bridge. It is unsuitable to adopt the moving load model and the moving mass model in the design. The proposed results can serve in the design of high-speed maglev three-span rigid frame bridges.展开更多
In this study, the intrinsic mechanism of aerodynamic effects on the motion stability of a high-speed maglev system was investigated. The concept of a critical speed for maglev vehicles considering the aerodynamic eff...In this study, the intrinsic mechanism of aerodynamic effects on the motion stability of a high-speed maglev system was investigated. The concept of a critical speed for maglev vehicles considering the aerodynamic effect is proposed. The study was carried out based on a single magnetic suspension system, which is convenient for proposing relevant concepts and obtaining explicit expressions. This study shows that the motion stability of the suspension system is closely related to the vehicle speed when aerodynamic effects are considered. With increases of the vehicle speed, the stability behavior of the system changes. At a certain vehicle speed,the stability of the system reaches a critical state, followed by instability. The speed corresponding to the critical state is the critical speed. Analysis reveals that when the system reaches the critical state, it takes two forms, with two critical speeds, and thus two expressions for the critical speed are obtained. The conditions of the existence of the critical speed were determined, and the effects of the control parameters and the lift coefficient on the critical speed were analyzed by numerical analysis. The results show that the first critical speed appears when the aerodynamic force is upward,and the second critical speed appears when the aerodynamic force is downward. Moreover, both critical speeds decrease with the increase of the lift coefficient.展开更多
The problem of time delay speed feedback in the control loop is considered here.Its effects on the linear stability and dynamic behavior of the maglev system are investigated.It is found that a Hopf bifurcation can ta...The problem of time delay speed feedback in the control loop is considered here.Its effects on the linear stability and dynamic behavior of the maglev system are investigated.It is found that a Hopf bifurcation can take place when the time delay exceeds certain values.The stability condition of the maglev system with the time delay is acquired.The direction and stability of the Hopf bifurcation are determined by constructing a center manifold and by applying the normal form method.Finally,numerical simulations are performed to verify the analytical result.展开更多
With the increasing demand of higher travelling speed,a new streamlined high-speed maglev train has been designed to reach a speed of 600 km/h.To better capture the flow field structures around the maglev train,an imp...With the increasing demand of higher travelling speed,a new streamlined high-speed maglev train has been designed to reach a speed of 600 km/h.To better capture the flow field structures around the maglev train,an improved delayed detached eddy simulation(IDDES)is adopted to model the turbulence.Results show that the new maglev train has good aerodynamic load performance such as small drag coefficient contributing to energy conservation.The main frequencies of aerodynamic forces for each car have a scattered distribution.There are two pairs of counter-rotating large vortices in the non-streamlined part of the train that make the boundary layer thicker.Many high-intensity vortices are distributed in the narrow space between skirt plates or train floor and track.In the gap between the train floor and track(except near the tail car nose),the main frequency of vortex shedding remains constant and its strength increases exponentially in the streamwise direction.In the wake,the counter-rotating vortices gradually expand and reproduce some small vortices that move downward.The vortex has quite random and complex frequencydomain distribution characteristics in the wake.The maximum time-averaged velocity of the slipstream occurs near the nose of the head car,based on which,the track-side safety domain is divided.展开更多
This paper presents a novel two-dimensional maglev servo proportional cartridge valve(2 D maglev valve),where a contactless maglev coupling is introduced between electro-mechanical converter and valve body to realize ...This paper presents a novel two-dimensional maglev servo proportional cartridge valve(2 D maglev valve),where a contactless maglev coupling is introduced between electro-mechanical converter and valve body to realize functions of force transmission,spool position feedback and linear-rotary motion conversion.Such configuration can effectively reduce cost of both valve manufacturing and electro-mechanical converter,while still maintain features of 2 D valve such as null pilot leakage,high power-to-weight ratio and excellent anti-pollution capacity.Firstly,the characteristic equation of the valve is derived using linear theory,and the stability criterion is established for parameter determination.The influences of crucial structural parameters such as initial height of overlapping area,width of high-pressure and low-pressure holes,acting radius of magnetic force,pitch angle of maglev coupling,length of sensitive chamber and system pressure on the dynamic response are investigated based on AMESim numerical simulation.The prototype valve is then designed and manufactured and a special test rig is built.The no-load flow characteristic,load flow characteristic,leakage characteristic,amplitude and phase frequency characteristics and step response under different system pressures are measured.The experimental results are in a good agreement with the simulated analysis.As an over-damped system,the prototype valve has excellent working stability,which can reach a no-load flow rate of 105.9 L/min with hysteresis of 3.51%,amplitude bandwidth of 28.7 Hz and phase bandwidth of 42.8 Hz under 21 MPa.The research indicates that the 2 D maglev valve can be a potential solution of flow rate control valve for flight control surface system of civil aircraft with high pressure and large flow rate application.展开更多
With rapid development of urban rail transit,maglev trains,benefiting from its comfortable,energy-saving and environmentally friendly merits,have gradually entered people's horizons.In this paper,aiming at improvi...With rapid development of urban rail transit,maglev trains,benefiting from its comfortable,energy-saving and environmentally friendly merits,have gradually entered people's horizons.In this paper,aiming at improving the aerodynamic performance of an urban maglev train,the aerodynamic optimization design has been performed.An improved two-point infill criterion has been adopted to construct the cross-validated Kriging model.Meanwhile,the multi-objective genetic algorithm and complex three-dimensional geometric parametrization method have been used,to optimize the streamlined head of the train.Several optimal shapes have been obtained.Results reveal that the optimization strategy used in this paper is sufficiently accurate and time-efficient for the optimization of the urban maglev train,and can be applied in practical engineering.Compared to the prototype of the train,optimal shape benefits from higher lift of the leading car and smaller drag of the whole train.Sensitivity analysis reveals that the length and height of the streamlined head have a great influence on the aerodynamic performance of the train,and strong nonlinear relationships exist between these design variables and aerodynamic performance.The conclusions drawn in this study offer the chance to derive critical reference values for the optimization of the aerodynamic characteristics of urban maglev trains.展开更多
In order to explore the precise dynamic response of the maglev train and verify the validity of proposed controller,a maglev guideway-electromagnet-air spring-cabin coupled model is developed in the first step.Based o...In order to explore the precise dynamic response of the maglev train and verify the validity of proposed controller,a maglev guideway-electromagnet-air spring-cabin coupled model is developed in the first step.Based on the coupled model,the stresses of the modules are analyzed,and it is pointed out that the inherent nonlinearity,the inner coupling,misalignments between the sensors and actuators,and external disturbances are the main issues that should be considered for the maglev engineering.Furthermore,a feedback linearization controller based on the mathematical model of a maglev module is derived,in which the nonlinearity,coupling and misalignments are taken into account.Then,to attenuate the effect of external disturbances,a disturbance observer is proposed and the dynamics of the estimation error is analyzed using the input-to-state stability theory.It shows that the error is negligible under a low-frequency disturbance.However,at the high-frequency range,the error is unacceptable and the disturbances can not be compensated in time,which lead to over designed fluctuations of levitation gap,even a clash between the upper surface of electromagnet and lower surface of guideway.To solve this problem,a novel nonlinear acceleration feedback is put forward to enhancing the attenuation ability of fast varying disturbances.Finally,numerical comparisons show that the proposed controller outperforms the traditional feedback linearization controller and maintains good robustness under disturbances.展开更多
The dynamic interaction between maglev vehicle and three-span continuous guideway is discussed. With the consideration of control system, the dynamic interaction model has been developed. Numerical simulation has been...The dynamic interaction between maglev vehicle and three-span continuous guideway is discussed. With the consideration of control system, the dynamic interaction model has been developed. Numerical simulation has been performed to study dynamic characteristics of the guideway. The results show that bending rigidity, vehicle speed, span ratio and primary frequency all have important influences on the dynamic characteristics of the guideway and there is no distinct trend towards resonance vibration when fl/（v/l） equals 1.0. The definite way is to control impact coefficient and acceleration of the guideway. The conclusions can serve the design of high-speed maglev three-span continuous guideway.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant 52432012in part by the Shanghai Science and Technology Project with 25ZR1402508。
文摘The stator of the maglev track plays a crucial role in the operation of the maglev system.Currently,the efficiency of maglev track inspection is limited by several factors,including the large span of elevated structures,manual visual inspection,short inspection window times,and limited GPS positioning accuracy.To address these issues,this paper proposes a deep learning-based method for detecting and locating stator surface damage.This study establishes a maglev track stator surface image dataset,trains different object detection models,and compares their performance.Ultimately,YOLO and ByteTrack object tracking algorithms were chosen as the basic framework and enhanced to achieve automatic identification of high-speed maglev track stator surface damage images and track and count stator surface localization feature images.By matching the identified damaged images with their corresponding stator segment and beam segment sequence numbers,the location of the damage is pinpointed to the corresponding stator segment,enabling rapid and accurate identification and localization of complex damage to the maglev track stator surface.
基金supported by the National Natural Science Foundation of China(12372049)Fundamental Research Funds for the Central Universities(2682023ZTPY036)Research and Development Project of JDD For HTS Maglev Transportation System(JDDKYCF2024002).
文摘High-speed maglev trains(HSMTs)can run at high running speeds due to their unique design.The pressure waves that these trains generate while passing each other are therefore very intense,and can even have safety implications.In order to reduce the transient impact of such waves,the standard k-ε turbulence model is used in this work to assess the effect of railway spacing on the aerodynamic loads,pressure and surrounding flow field of 600 km/h maglev trains passing each other in open air.The sliding mesh technique is used to determine the relative motion between the considered trains.The results show that the surface pressure is approximately linearly correlated with the square of the speed while the amplitude of the pressure wave on the train surface,side force,and rolling moment all have negative exponential relationships with the railway spacing.
基金Projects(2022YFB4301201-02,2023YFB4302502-02)supported by the National Key R&D Program of ChinaProjects(52372369,52302447,52388102)supported by the National Natural Science Foundation of China。
文摘To address the severe aerodynamic effects caused by a 600 km/h superconducting maglev train passing through a tunnel at full speed,this study systematically investigates the coupled influence of auxiliary facility parameters including the shaft(location L,cross sectional dimension W,height h),tunnel portal(cross sectional area S),and openings(spacing D,side length F)on the evolution of tunnel aerodynamic effects.By integrating three dimensional unsteady flow field numerical simulations with a dynamic model testing system,the research notably reveals the regulatory mechanisms of these parameters on the evolution characteristics of the initial compression wave pressure gradient and the multi peak structure of micro-pressure waves.The results show that shaft parameters significantly affect the initial compression wave.Both the wave amplitude and gradient exhibit a linear negative correlation with cross sectional dimension W and a linear positive correlation with location L,while demonstrating a nonlinear relationship with height h,the amplitude follows a cubic polynomial trend,and the gradient initially increases before plateauing.Under the configuration W=8 m,L=50 m,and h=20 m,substantial reductions in both compression wave amplitude and gradient were achieved.The portal cross sectional area S shows a"U-shaped"relationship with the compression wave gradient,with the maximum gradient reduction of 53.24%occurring at S=210 m^(2),a result comparable to that achieved with optimized opening parameters(D=15 m,F=3.5 m,53.96%).Regarding micro-pressure waves,the amplitude measured 20 m from the tunnel exit shows a linear positive correlation with shaft parameters L and W,while the influence of h saturates beyond 50 m.Reductions exceeding 54%were achieved with portal parameters,either at S=210 m^(2) or using the optimized opening configuration.Furthermore,micro-pressure waves near the portal exhibit a consistent dual peak structure:the first peak originates from the train entry compression wave,and the second results from further wave compression after tunnel exit.The opening location governs selective peak regulation openings near the portal entrance primarily suppress the first peak with minimal impact on the second,whereas centrally located openings reduce the first peak but can amplify the second by up to 3%.Based on these insights,an optimized parameter configuration is proposed:a shaft with a cross-sectional dimension≥8 m located 50 m from the portal,a portal cross sectional area of 210 m^(2),and openings spaced at 15 m intervals.This configuration can reduce the initial compression wave gradient by over 50%.The results provide a theoretical foundation for controlling aerodynamic effects of superconducting maglev train.
基金National Natural Science Foundation of China under Grant Nos.52478467and 52108417Guangdong Basic and Applied Basic Research Foundation under Grant No.2024A1515012569the Natural Science Basic Research Program of Shaanxi under Grant No.2021JQ-101。
文摘A ground girder is laid on the preprocessed subgrade by gravity compaction and integrally uniformly supported by subgrade in maglev transit.The settlement of the maglev subgrade inevitably affects the vibration state of the medium and low speed maglev coupled system by the additional deformation of the maglev track.This study investigated the dynamic properties of the coupled vibration system affected by the subgrade settlement.First,a theoretical coupled vibration model of a maglev train-track-ground girder system with uneven subgrade settlement was proposed and verified.Then,the effect mechanism of the coupled system caused by the uneven subgrade settlement was explored.Finally,settlement types and subgrade support voiding were examined.The analysis showed that the uneven subgrade settlement considerably increased the dynamic responses of the levitation control system and maglev vehicle while having a minor influence on those of the track-ground girder.The influence of a single ground girder settling was the strongest,and adjacent sides’settling of two ground girders was the weakest for the vibration of a maglev train.An extremely large uneven settlement exceeding 6 mm led to active levitation control system instability.The subgrade support voiding enlarged the vehicle-induced vibration of the track ground girder.
基金Project(52202426)supported by the National Natural Science Foundation of ChinaProjects(15205723,15226424)supported by the Research Grants Council of the Hong Kong Special Administrative Region,China。
文摘Maglev trains experience significant aerodynamic effects when passing through tunnels.A moving model test was conducted to explore the practical effects of speed reduction and entrance buffer structures on mitigating tunnel/maglev aerodynamic effects.It is found that both have an overall positive effect on mitigating the aerodynamic environment inside and outside the tunnel.Trains operating at 200 km/h show a 49.8%decrease in peak-to-peak pressure and a 50.7%decrease in transient pressure instability on inner walls compared to those at 280 km/h.Lower speeds resulted in a 65.6%decrease in amplitude and a 24.5%decrease in decay rate,both of which are parameters for exponential fittings of pressure peaks that decay naturally after the train leaves.The buffer structures result in a reduction of up to 25.7%in the maximum positive pressure and a 29.0%decrease in transient pressure instability.Additionally,a reduction in amplitude of up to 21.2%and a 32.2%increase in decay rate were observed with the use of buffer structures.Nevertheless,it is difficult to conclude direct correlations between the maximum pressure,peak-to-peak values,etc.,and the speeds or buffer structures due to the complex wave propagation in tunnels.However,speed reduction and buffer structures are proven to be effective in reducing the micro-pressure wave levels with a simpler monotonic relationship.
基金supported by the National Natural Science Foundation of China(No.U23A20681)the S&T Program of Hebei Province,China(No.23567602H).
文摘Currently,the design of high-temperature superconducting(HTS)maglev trains adopts a U-shaped track operation mode,and the height of the side track significantly impacts the train’s aerodynamic characteristics.In this study,we used computational fluid dynamics(CFD)methods,based on the 3D Reynolds-averaged Navier-Stokes(RANS)method and shear stress transport(SST)k-ωturbulence model,to deeply investigate the effects of the presence or absence of a U-shaped track and different side track heights(800,880,and 960 mm)on the pressure distribution,velocity distribution,and flow field structure of HTS maglev trains at a speed of 400 km/h under crosswinds.The numerical methods were verified using a scaled ICE-2 model wind tunnel test.First,the aerodynamic characteristics of the train under different wind direction angles with and without side tracks were studied.We found that the aerodynamic performance of the train is the most adverse when the wind direction angle is 90°.The presence of a U-shaped track can effectively reduce the lateral force,lift,and yawing moment of the train.The aerodynamic performance of the first suspension bogie at the bottom,which is the worst,will also be effectively improved.Next,the aerodynamic effects of different side track heights on the HTS maglev train were studied.An increase in side track height will reduce the lift and lateral force of the train,while the increase in drag is relatively small.Under the premise of ensuring passengers can conveniently alight,we found that a U-shaped track with a side track height of 960 mm has the best aerodynamic performance.The research findings offer a valuable reference for the engineering application and design of the track structure of HTS maglev train systems.
基金Project(U24B20125)supported by the National Natural Science Foundation of ChinaProject(K2024T005)supported by the China National Railway Group Science and Technology Program。
文摘The suspension gap is a critical operational parameter for high-speed maglev trains and significantly impacts their aerodynamic performance.Based on an engineering prototype of the high-temperature superconducting(HTS)pinning maglev train,this study established a detailed three-dimensional model,and then the aerodynamic characteristics of the HTS maglev train at 600 km/h with suspension gaps of 10 mm,20 mm,and 30 mm were simulated based on the improved delayed detached eddy simulation(IDDES)turbulence model and SST kωtwo-equation.The results demonstrated that the underbody design of the HTS maglev train leads to unique aerodynamic drag and aerothermal distribution phenomena.The head car experiences the smallest drag,while the tail car experiences the largest.The aerothermal temperature on the train's bottom surface progressively increases from the head to the tail.Additionally,the U-shaped track significantly constrains the flow around the train body,forming strong vortex structures.As the suspension gap increases from 10 mm to 30 mm,the airflow velocity in the train-track gap rises,reducing the underbody pressure and decreasing the lift of the head car by 12.43%.The drag of the head car increases by 10.98%,primarily due to changes in pressure drag.Additionally,the temperature at the underbody of the tail car rises further due to significant airflow deceleration.These findings provide valuable insights for advancing the engineering design and application of the high-speed HTS maglev technology.
基金Project(JZ202201)supported by the Key Project of Basic and Applied Basic Research of Jiangmen,ChinaProject(2021WGALH15)supported by the Hong Kong and Macao Joint Research and Development Fund of Wuyi University,China+2 种基金Project(S202411349091)supported by the University Students'Innovation and Entrepreneurship Project of Guangdong,ChinaProject(52202426)supported by the National Natural Science Foundation of ChinaProjects(15205723,15226424)supported by the Research Grants Council(RGC)of the Hong Kong Special Administrative Region,China。
文摘Evacuated tube transportation(ETT)offers a promising high-speed transport solution,but trains operating at supersonic speeds within a sealed tube can induce complex aerodynamic phenomena that impact safety and reliability.This study utilized the Reynolds-averaged Navier-Stokes(RANS)shear stress transport k-ω(SST k-ω)turbulence model for steady-state simulations and the improved delayed detached eddy simulation(IDDES)SST k-ωmodel for unsteady state simulations,both coupled with the advection upstream splitting method(AUSM).Four tunnel cross-sectional areas(49 m^(2),64 m^(2),81 m^(2),and 100 m^(2))with corresponding blockage ratios(β)(0.253,0.192,0.150,0.121)were analyzed to explore shock wave formation and its dependence on blockage ratios,along with surface pressure distribution and aerodynamic loading.Results show that higher blockage ratios increase shock wave intensity,while larger tunnel areas reduce this intensity,improving flow structure and wake effects.Moreover,as the blockage ratio decreases,the total drag coefficient of the entire train decreases linearly.When the blockage ratio decreases from 0.253 to 0.121,the total drag coefficient of the entire train decreases by 46.2%,with the head carriage and tail carriage drag coefficients decreasing by 23.3%and 32.7%,respectively,while the drag coefficient of the middle carriage remains nearly unchanged.The percentage of the total drag coefficient contributed by the head carriage decreases from 51.1%to 40.9%,while the percentage for the tail carriage increases from 47.0%to 56.6%.These findings enhance understanding of ETT fluid dynamics and performance.
基金Project(2025A1515011803)supported by the Guangdong Basic and Applied Basic Research Foundation,ChinaProject(2023JC01020)supported by the Jiangmen Basic and Theoretical Science Research Project,China。
文摘The increasing aerodynamic noise caused by high-speed maglev trains(HSMTs)contributes substantially to environmental pollution and passenger discomfort.Numerical studies were performed to examine the effect of air blowing/sucking modes,positions and velocities on the flow field change and their potentials in mitigating the aerodynamic noise produced by HSMTs.The results indicate that the aerodynamic noise can be effectively mitigated by implementing air-blowing in the transition region between the streamlined tail nose and constant cross-sectional body(Scheme 1)and the wake vortex shedding area near the tail nose(Scheme 3)at speeds below 0.3 U(train speed),as well as in the side edge area(Scheme 2)at various speeds(0.1 U-0.5 U),primarily due to the suppression in wake vortices.The optimal noise reduction value of 1.53 dB(A)is achieved when blowing in Scheme 1 at a speed of 0.1 U,while the efficacy of the air-sucking mode is inferior with a smaller noise reduction value less than 0.84 dB(A).Additionally,simultaneous reductions in aerodynamic noise and drag can be achieved when sucking in Scheme 2 at speeds below 0.2 U and blowing in Scheme 3 at speeds below 0.3 U.These findings offer valuable insights for the application of active flow control technology in the design of low-resistance and low-noise HSMTs.
基金funded by Research and Development Project of JDD For HTS Maglev Transportation System(NO.JDDKYCF2024002)ChinaNational Railway Group Science and Technology Program grant(K2024T005).
文摘High-speed maglev trains represent a key direction for the future development of rail transportation.As operating speeds increase,they face increasingly severe aerodynamic challenges.The streamlined aerodynamic shape of a maglev train is a critical factor influencing its aerodynamic performance,and optimizing its length plays a significant role in improving the overall aerodynamic characteristics of the train.In this study,a numerical simulation model of a high-speed maglev train was established based on computational fluid dynamics(CFD)to investigate the effects of streamline length on the aerodynamic performance of the train operating on an open track.The results show that the length of the streamlined section has a pronounced impact on aerodynamic performance.When the streamline length increases from 8.3 to 14.3 m,the aerodynamic drag of the head and tail cars decreases by 16.2%and 32.1%,respectively,with reductions observed in both frictions drag and pressure drag-the latter showing the most significant decrease in the tail car.Moreover,the extended streamline length effectively suppresses flow separation on the train body surface.The intensity of the positive pressure region on the upper surface of the head car streamlined section is reduced,directly leading to a 38.2%reduction in lift.This research provides a theoretical basis for the parametric design of aerodynamic shapes for high-speed maglev trains and offers guidance and recommendations for drag and lift reduction optimization.
基金Project(24A0006)supported by the Key Project of Scientific Research Fund of Hunan Provincial Department of Education,ChinaProject(2024JJ5430)supported by the Natural Science Foundation of Hunan Province,ChinaProjects(2024JK2045,2023RC3061)supported by the Science and Technology Innovation Program of Hunan Province,China。
文摘A high-speed train travelling from the open air into a narrow tunnel will cause the“sonic boom”at tunnel exit.When the maglev train’s speed reaches 600 km/h,the train-tunnel aerodynamic effect is intensified,so a new mitigation method is urgently expected to be explored.This study proposed a novel asymptotic linear method(ALM)for micro pressure wave(MPW)mitigation to achieve a constant gradient of initial c ompression waves(ICWs),via a study with various open ratios on hoods.The properties of ICWs and MPWs under various open ratios of hoods were analyzed.The results show that as the open ratio increases,the MPW amplitude at the tunnel exit initially decreases before rising.At the open ratio of 2.28%,the slope of the ICW curve is linearly coincident with a supposed straight line in the ALM,which further reduces the MPW amplitude by 26.9%at 20 m and 20.0%at 50 m from the exit,as compared to the unvented hood.Therefore,the proposed method effectively mitigates MPW and quickly determines the upper limit of alleviation for the MPW amplitude at a fixed train-tunnel operation condition.All achievements provide a ne w potential measure for the adaptive design of tunnel hoods.
基金Project(2021zzts0775) supported by the Independent Exploration and Innovation Project for Graduate Students of Central South University,ChinaProject(2021JJ30053) supported by the Hunan Natural Science Foundation,China。
文摘The risk of failure of the control loop can occur when a high-speed maglev train runs on viaduct.Meanwhile,the failure of the levitation magnets which balances the gravity of the maglev train could cause the train collision with track.To study the dynamic response of the train and the viaduct when the levitation magnet control loop failure occurs,a high-speed maglev train-viaduct coupling model,which includes a maglev controller fitted by measured force-gap data and considers the actual structure of train and viaduct,is established.Then the accuracy and effectiveness of the established approach are validated by comparing the computed dynamic responses and frequencies with the measurement results.After that,the dynamic responses of maglev train and viaduct are discussed under normal operation and control loop failures,and the most disadvantageous combination of control loop failures is obtained.The results show that when a single control loop fails,it only has a great influence on the failed electromagnet,and the maglev response of adjacent electromagnets has no obvious change and no collision occurs.But there is a risk of rail collisions when the dual control loop fails.
基金The National High Technology Research and Development Program of China (863Program)(No2005AA505440)
文摘The dynamic interaction between the maglev vehicle and the three-span rigid frame bridge is discussed. With the consideration of magnetic force, the interaction model is developed. Numerical simulations are performed to study the dynamic characteristics of the bridge during vehicle movement along the bridge. The results show that a reasonable value of the linear stiffness ratio of columns to beams is between 2. 0 and 3.0. The dynamic responses of the bridge are aggravated with the decrease in bending rigidity and the increase in vehicle speed and the span ratio of the bridge. It is suggested that a definite way is to control impact coefficients and acceleration in the dynamic design of the bridge. It is unsuitable to adopt the moving load model and the moving mass model in the design. The proposed results can serve in the design of high-speed maglev three-span rigid frame bridges.
基金supported by the National Key Research and Development Program of China(Grant 2016YFB1200602)the National Natural Science Foundation of China (Grants 11672306, 51490673)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant XDB22020101)the National Basic Research Program (973 Program) of China (Grant 2014CB046801)the State Key Laboratory of Hydraulic Engineering Simulation and Safety (Tianjin University)
文摘In this study, the intrinsic mechanism of aerodynamic effects on the motion stability of a high-speed maglev system was investigated. The concept of a critical speed for maglev vehicles considering the aerodynamic effect is proposed. The study was carried out based on a single magnetic suspension system, which is convenient for proposing relevant concepts and obtaining explicit expressions. This study shows that the motion stability of the suspension system is closely related to the vehicle speed when aerodynamic effects are considered. With increases of the vehicle speed, the stability behavior of the system changes. At a certain vehicle speed,the stability of the system reaches a critical state, followed by instability. The speed corresponding to the critical state is the critical speed. Analysis reveals that when the system reaches the critical state, it takes two forms, with two critical speeds, and thus two expressions for the critical speed are obtained. The conditions of the existence of the critical speed were determined, and the effects of the control parameters and the lift coefficient on the critical speed were analyzed by numerical analysis. The results show that the first critical speed appears when the aerodynamic force is upward,and the second critical speed appears when the aerodynamic force is downward. Moreover, both critical speeds decrease with the increase of the lift coefficient.
基金Supported by National Natural Science Foundation of China(604040037 and Fork Ying-Dong Education Foundation(94028)
文摘The problem of time delay speed feedback in the control loop is considered here.Its effects on the linear stability and dynamic behavior of the maglev system are investigated.It is found that a Hopf bifurcation can take place when the time delay exceeds certain values.The stability condition of the maglev system with the time delay is acquired.The direction and stability of the Hopf bifurcation are determined by constructing a center manifold and by applying the normal form method.Finally,numerical simulations are performed to verify the analytical result.
基金Project supported by the National Natural Science Foundation of China(No.51605397)the National Key R&D Program of China(No.2016YFB1200602-15)the Sichuan Provincial Science and Technology Support Program(No.2019YJ0227),China。
文摘With the increasing demand of higher travelling speed,a new streamlined high-speed maglev train has been designed to reach a speed of 600 km/h.To better capture the flow field structures around the maglev train,an improved delayed detached eddy simulation(IDDES)is adopted to model the turbulence.Results show that the new maglev train has good aerodynamic load performance such as small drag coefficient contributing to energy conservation.The main frequencies of aerodynamic forces for each car have a scattered distribution.There are two pairs of counter-rotating large vortices in the non-streamlined part of the train that make the boundary layer thicker.Many high-intensity vortices are distributed in the narrow space between skirt plates or train floor and track.In the gap between the train floor and track(except near the tail car nose),the main frequency of vortex shedding remains constant and its strength increases exponentially in the streamwise direction.In the wake,the counter-rotating vortices gradually expand and reproduce some small vortices that move downward.The vortex has quite random and complex frequencydomain distribution characteristics in the wake.The maximum time-averaged velocity of the slipstream occurs near the nose of the head car,based on which,the track-side safety domain is divided.
基金the National Natural Science Foundation of China(Nos.51975524 and 51405443)the National Key Research and Development Program(No.2019YFB2005201)。
文摘This paper presents a novel two-dimensional maglev servo proportional cartridge valve(2 D maglev valve),where a contactless maglev coupling is introduced between electro-mechanical converter and valve body to realize functions of force transmission,spool position feedback and linear-rotary motion conversion.Such configuration can effectively reduce cost of both valve manufacturing and electro-mechanical converter,while still maintain features of 2 D valve such as null pilot leakage,high power-to-weight ratio and excellent anti-pollution capacity.Firstly,the characteristic equation of the valve is derived using linear theory,and the stability criterion is established for parameter determination.The influences of crucial structural parameters such as initial height of overlapping area,width of high-pressure and low-pressure holes,acting radius of magnetic force,pitch angle of maglev coupling,length of sensitive chamber and system pressure on the dynamic response are investigated based on AMESim numerical simulation.The prototype valve is then designed and manufactured and a special test rig is built.The no-load flow characteristic,load flow characteristic,leakage characteristic,amplitude and phase frequency characteristics and step response under different system pressures are measured.The experimental results are in a good agreement with the simulated analysis.As an over-damped system,the prototype valve has excellent working stability,which can reach a no-load flow rate of 105.9 L/min with hysteresis of 3.51%,amplitude bandwidth of 28.7 Hz and phase bandwidth of 42.8 Hz under 21 MPa.The research indicates that the 2 D maglev valve can be a potential solution of flow rate control valve for flight control surface system of civil aircraft with high pressure and large flow rate application.
基金This work was supported by Advanced Rail Transportation Special Plan in National Key Research and Development Project(Grants 2016YFB1200601-B13 and 2016YFB1200602-09)Youth Innovation Promotion Association CAS(2019020).
文摘With rapid development of urban rail transit,maglev trains,benefiting from its comfortable,energy-saving and environmentally friendly merits,have gradually entered people's horizons.In this paper,aiming at improving the aerodynamic performance of an urban maglev train,the aerodynamic optimization design has been performed.An improved two-point infill criterion has been adopted to construct the cross-validated Kriging model.Meanwhile,the multi-objective genetic algorithm and complex three-dimensional geometric parametrization method have been used,to optimize the streamlined head of the train.Several optimal shapes have been obtained.Results reveal that the optimization strategy used in this paper is sufficiently accurate and time-efficient for the optimization of the urban maglev train,and can be applied in practical engineering.Compared to the prototype of the train,optimal shape benefits from higher lift of the leading car and smaller drag of the whole train.Sensitivity analysis reveals that the length and height of the streamlined head have a great influence on the aerodynamic performance of the train,and strong nonlinear relationships exist between these design variables and aerodynamic performance.The conclusions drawn in this study offer the chance to derive critical reference values for the optimization of the aerodynamic characteristics of urban maglev trains.
基金Project(60404003)supported by the National Natural Science Foundation of China
文摘In order to explore the precise dynamic response of the maglev train and verify the validity of proposed controller,a maglev guideway-electromagnet-air spring-cabin coupled model is developed in the first step.Based on the coupled model,the stresses of the modules are analyzed,and it is pointed out that the inherent nonlinearity,the inner coupling,misalignments between the sensors and actuators,and external disturbances are the main issues that should be considered for the maglev engineering.Furthermore,a feedback linearization controller based on the mathematical model of a maglev module is derived,in which the nonlinearity,coupling and misalignments are taken into account.Then,to attenuate the effect of external disturbances,a disturbance observer is proposed and the dynamics of the estimation error is analyzed using the input-to-state stability theory.It shows that the error is negligible under a low-frequency disturbance.However,at the high-frequency range,the error is unacceptable and the disturbances can not be compensated in time,which lead to over designed fluctuations of levitation gap,even a clash between the upper surface of electromagnet and lower surface of guideway.To solve this problem,a novel nonlinear acceleration feedback is put forward to enhancing the attenuation ability of fast varying disturbances.Finally,numerical comparisons show that the proposed controller outperforms the traditional feedback linearization controller and maintains good robustness under disturbances.
基金Project (No. 2005AA505440) supported by the Hi-Tech Researchand Development Program (863) of China
文摘The dynamic interaction between maglev vehicle and three-span continuous guideway is discussed. With the consideration of control system, the dynamic interaction model has been developed. Numerical simulation has been performed to study dynamic characteristics of the guideway. The results show that bending rigidity, vehicle speed, span ratio and primary frequency all have important influences on the dynamic characteristics of the guideway and there is no distinct trend towards resonance vibration when fl/（v/l） equals 1.0. The definite way is to control impact coefficient and acceleration of the guideway. The conclusions can serve the design of high-speed maglev three-span continuous guideway.
