Simple Catenary Research Articles

An exploration of the super-critical speed dynamic behaviours of the pantograph-catenary system

The train operating speed is traditionally limited to lower than 0.7 times the critical speed of the catenary. The material’s strength limits the tensile forces of the tension wires, preventing the further improvement of the train speed. A novel super-critical speed operating strategy of the pantograph catenary system (PCS) is proposed, using the relatively low tensile values of the catenary to make the pantograph run at a speed ratio larger than 1. The analytical results of a string under a moving load show the theoretical possibility of the super-critical speed operating strategy in moving load problems. The finite element method (FEM) is adopted for the model of the catenary. The differences between the simple catenary and the stitched catenary running at the super-critical speed regime are compared. Then, the tensile forces designation of the stitched catenary with different speed ratio values beyond 400 km/h is studied. Finally, the dynamic behaviours of the PCS reaching the super-critical speed regime are discussed, consisting of the continuous acceleration process and the transition process from the high-tension section to the low-tension section. The proposed super-critical speed operating strategy may be promising for the next-generation high-speed PCS.

Verification of SIMPACK-MoorDyn coupling using 15 MW IEA-Wind reference models Activefloat and WindCrete

The modelling of mooring lines and their behaviour is essential for the research and development of Floating Offshore Wind Turbines (FOWTs). Mooring lines’ dynamics impact the platform motions and hence the loads on the turbine’s blades. Therefore, coupling the mooring lines’ dynamics in the aero-hydro-servo-elastic models is a necessity. In this paper we couple Moordyn to SIMPACK which is a multibody system simulation software. Afterwards, we verify the coupling by comparing the results to OpenFAST v2.1. The IEA Wind 15 MW reference wind turbine coupled to Activefloat and WindCrete floaters, introduced in COREWIND project, are used for the verification process. The two floaters have two different mooring configurations; WindCrete is a spar floater with a symmetric delta shape catenary mooring line system, while Activefloat is a semi-submersible with simple catenary mooring configurations. During the verification, both steady and dynamic load cases are used for the responses of two mooring systems. After the verification, the coupling procedure is open access and can be used to model new innovations in FOWTs using SIMPACK benefiting from the tool’s flexibility.

On-line monitoring aided evaluation of power line cable shapes

The paper presents a novel method that by coupling of the measurement data with an advanced 3D, extensible cable model allows for the prediction of power line configuration. The method, which may be considered as an example of the predictive digital twin, is presented in two variants that were validated throughout a comparison of the predictions with an in situ geodetic surveying. It has resulted in an excellent agreement of the computed and the real power cable shapes and confirmed reliability of the proposed approaches. We use on-line measured temperature and inclinations at a certain point on a cable to enhance the non-linear mechanical model (not the simple catenary curve) of the cable sag. The proposed coupling of the real data and a computational model is done twofold, by modification of either selected parameters or equations used to model power cable configuration. In both approaches, our power cable model is combined with a rigid body model of insulator chains. The proposed predictions with quantified uncertainties may support the power line dynamic rating that in turn may significantly increase the capacity of electric transmission systems. The key component of such systems is the processing of the collected data in order to determine the maximum current that can be transmitted safely, without violating the required clearance space. Making use of the advanced 3D, extensible cable model, instead of the catenary curve, insignificantly increases computation time, however it enables taking into account out of plane loading (wind), data overload as well as effective using of measurement uncertainties.

A tabular optimisation technique for steel lazy wave riser

Steel lazy wave riser (SLWR) is derived from the simple catenary riser (SCR) by the installation of buoyancy modules on its section. Infinite SLWR configurations are possible, and this poses difficulties in determining the best configuration. However, it is possible to capture some suitable configurations which satisfy some given design criteria specific to a project. We referred to these as the optimum configurations for the problem. Several advanced optimization tools and techniques for engineering optimization are available. In this paper, we present a 2D tabular optimization method for SLWR, which is an index-based optimization technique. The approach reduces a multidimensional problem to a 2D type providing a significant reduction in the required computational resources. It combines the design variables in pairs and assigns indices to the resulting design points (configurations) for each combination. The optimum design points are then tracked through index matching using techniques such as data sorting and intersection operations. In the application of the technique to SLWR design, we set the number of design variable for the problem to three. This results in three pair of combinations of the design variables. The design variables are the apparent mass ratio, the sag bend elevation, and the arc height. The output variables of interest to be optimized include the SLWR hanging length, the smeared buoyancy section length, the smeared buoyancy thickness, the riser hang-off tension, the stress utilization and fatigue damage around the bends. Selected optimum SLWR configurations from the optimization process are subjected to an irregular wave simulation to demonstrate the suitability of the approach for such optimisation problems.

<b>Development of Simple Catenary System for Operation over 300 km/h</b>

<b>Development of Simple Catenary System for Operation over 300 km/h</b>

Study on Galloping Oscillation of Iced Catenary System under Cross Winds

This paper mainly aims at revealing the nature of the galloping oscillation of iced catenary system under cross winds. The aerodynamic force on the iced catenary system is assumed to be quasi-steady, and then the quasi-steady aerodynamic lift and drag coefficients are completed in FLUENT. By fitting the discrete simulation data, the expression of the vertical aerodynamic force is further obtained. According to the Den Hartog vertical galloping mechanism, the stability of iced catenary is discussed and the initial icing angle corresponding to the critical stability is obtained. On this basis, the dynamic model of the simple iced catenary system under cross winds is established. The partial differential vibration equation of the system is converted into the ordinary differential equation by the Galerkin method and then numerically solved. The condition of the unstable catenary motion in simulation is in agreement with that from theoretical stability analysis. In addition, the effects of structural damping, initial icing angle, and wind velocity on the system responses are investigated.

Finite element analysis of pantograph-catenary dynamic interaction

Numerical simulations of the pantograph-catenary dynamic interaction allow for assessment of the current collection quality provided by this subsystem at the design stage of the pantograph or the catenary system. In this paper, the authors present numerical results of simulations of the dynamic interaction between a pantograph and a catenary. Adopted catenary and pantograph models are consistent with the reference model presented in the EN 50318:2002 document, which describes the validation procedure of the simulation for the dynamic interaction between pantograph and overhead contact line. Authors have used the Finite Element Method to analyze this complex system. Ten catenary spans of simple catenary (one messenger wire and one contact wire) are modelled, each of them is 60m long. The pre-sag of the catenary is 0mm and the model of the catenary includes the stagger which equals ±200mm. The pantograph model consists of lumped masses which are connected each other with spring-damper elements. First, the static initial configuration is obtained (under gravity and tensioning loads), after which the dynamic transient simulation is conducted. Obtained results for the contact force and uplifts at supports are within the reference ranges presented in the EN 50318:2002 document, therefore it can be considered that the adopted model correctly reproduces the dynamic behaviour of the pantograph-catenary dynamic interaction.

400km/h 전차선로에서 사전이도가 집전성능에 미치는 영향에 대한 시뮬레이션 및 시험

A 400km/h simple catenary system was constructed as a test line in Korea. In the design stage of this system, the pre-sag was one of the engineering issues most focused on. It is known that the pre-sag improves the current collection performance in a certain band of high speed. However, the effect of pre-sag at 400km/h has not yet been established. To grasp a better pre-sag in the 400km/h catenary, we transacted the dynamic performance prediction simulation between catenary and pantograph under conditions of 0 and 1/3000 pre-sag. The level of 0 pre-sag was adapted for the 400km/h catenary design after reviewing predictions. We constituted the 1/3000 pre-sag sample section (about 1km) while constructing the 400km/h catenary test-bed (28km) of 0 pre-sag. With a HEMU-430X train, the contact forces were measured in the test-bed including the pre-sag sample section. In this paper, the predicted and measured dynamic performance values (contact forces) for 0 and 1/3000 pre-sag are described and compared. It is conclusively confirmed by analytical and experimental examination that the non pre-sag showed better dynamic (current collection) performance than that of the 1/3000 pre-sag for the 400km/h catenary system.

Analysis on J lay of SCR based on catenary and large deflection beam theory

This paper mainly focuses on J lay of Steel Catenary Riser, and proposes a new model using Sectional Mechanics Model, by iterating and composing catenary method and large deflection method. First the initial deformation and reaction force are evaluated by simple catenary model. For the pipe section with large deformation, asymptotic expansion in singular perturbation techniques pursues the solutions of second-order nonlinear governing equation. Comparison between these three methods shows that the new model displays very close results with high-accuracy large deflection model. This new model is also performed to evaluate the sensitivity of top tension, wet weight, and stiffness on the riser.

A nonlinear model for deepwater steel lazy-wave riser configuration with ocean current and internal flow

Steel lazy-wave riser (SLWR) has gained a viable solution as a kind of advanced steel catenary riser (SCR) to meet the increasing challenges of simple catenary riser on large hang-off tension and fatigue damage of touchdown point (TDP) in deepwater applications. The configuration and static performance of SLWR are essential during its design stage and varies a lot when subjected to loading from ocean current and internal flow. The governing equations which consist of conventional small deformation beam theory for the portion of pipeline lying on the seabed, coupled with a large deformation beam theory for the suspended section are established. The proposed model with appropriate boundary conditions can simulate the nonlinear mechanical behavior of SLWR with the effect of pipe–soil interaction, ocean current and internal flow. The finite difference method is adopted to obtain the numerical results, and comprehensive parametric analysis is carried out to investigate the influences of ocean current and internal flow on the riser’s static performance. The proposed model can be an important reference for the design and analysis of deepwater SLWR.

Numerical solutions for nonlinear large deformation behaviour of deepwater steel lazy-wave riser

To meet the increasing challenges of simple steel catenary riser on large hang-off tension and fatigue damage of the touchdown point (TDP) in deepwater or ultra deepwater applications, the steel lazy-wave risers (SLWR) have gained a viable solution. This paper is focused on the static equilibrium of SLWR which is of great importance to the basic configuration design of the riser. A more accurate model based on nonlinear large deformation beam theory is proposed to simulate the suspended part of SLWR, having evident advantage over previously applied small deformation beam or catenary theory which ignores the riser's bending stiffness and is hard to simulate the rapid change of the inclination angle. The model also deals with the pipe–soil interaction for simulating the TDP. The finite difference method is applied to obtain the numerical solutions. The results are comparatively in agreement with OrcaFlex. As an application, parametric analysis of the SLWR is carried out to investigate the influences of arc length of buoyancy section, arc length of upper section and soil stiffness on the static performance. The proposed model can be a basic reference for the dynamic analysis of the deepwater SLWR.

전차선로 전기적 특성 평가 시스템 구현

Currently in Korea, the simple catenary type overhead contact line system is being applied to both conventional lines and high speed lines of electric railway, and circulation current flowing into the catenary system frequently bring undesirable consequences. Namely, the connector wire has many problems according to a flow of excessive circulation current and arc current on catenary when an electric train runs at high speed. This paper presents the development and application of a real-time data acquisition system designed to measure the electrical characteristics of an overhead catenary system in electric railways. The developed system is capable of storing data of a 25 kV power source in a live wire state through a telemetry environment. The field test results show that the proposed technique and the developed system can be practically applied to measure characteristics of current of an overhead catenary system.

Investigation on dynamic performance and parameter optimization design of pantograph and catenary system

The dynamic performance of the simple catenary and the pantograph was simulated. The model of the catenary was established with the finite element method (FEM), and the pantograph was also simplified as a lumped mass model. Furthermore, based on the contact element between pantograph and catenary and the time integration method, the dynamic simulation of pantograph and catenary system was performed and the results of dynamic performance was obtained. According to the simulation results, it shows that the pantograph can run at a speed of 250 km/h and the contact loss is detected for the speed larger than 250 km/h. Subsequently the influence of the design parameters on the contact force was discussed and the optimization of the parameters was performed, the results show that the parameters, including the stiffness and damping of the pan-head and frame, the static lifted force and the tension of the contact wire, have a heavy influence on the dynamic performance of pantograph and catenary system. At last, a comparison of the contact force with the test datum is carried out, and it is showed that the agreement between the simulation results and the test datum is generally good.

Development of Simple Catenary Equipment Using PHC Contact Wire for Shinkansen

Public awareness of global warming and recycling has created a demand to respect environmental conservation and reduce the environmental burden posed by railways. To this end, it is necessary to extend the replacement frequency of the contact wire in the overhead contact line system and apply a copper alloy to improve its recycling efficiency. We therefore selected a new type of equipment (known as PHC simple catenary equipment) through research into the overhead contact line system, performance calculations from simulation, and running tests at our institute. In the final stage of development, we installed the PHC simple catenary equipment on a commercial line to confirm its performance.

Features of Contact Wire Wear and Measures for Local Wear on Simple Catenary with Copper-Steel Contact Wire

A simple catenary with copper-steel contact wire is one of overhead contact lines equipped high-speed lines as Shinkansen. Local wear of the contact wires were visible at the simple catenary with copper-steel contact wire of commercial lines. In addition, the result of the investigation on this line revealed that the wear occurred at overlaps of the overhead contact line and a part of station. The authors therefore proposed a measure for local wear at the overlaps, and verified the effects on a commercial line. Furthermore, we clarified the cause of wear by monitoring the sliding surfaces of the contact wires at the stations.

Dynamic Response of Risers Conveying Fluid

Riser conveying fluid is one category in a wide research area known as moving continua dynamic that was the subject to many research studies in the past 50 yr. The structure investigated in this paper is assumed to be a flexible pipe having a geometry of a simple catenary with a buoyancy force at the top. The riser is modeled as a beamlike continuous system subjected to wave, current, and wind forces. The derivation of the partial differential equation of motion included the following aspects: nonlinearities due to geometry, i.e., large displacements as well as wave drag force, fluid internal and external pressure, and internal fluid velocity and acceleration. The wave forces are approximated via Morison’s equation, where the drag force is proportional to the square of the relative velocity between the riser and the waves. All forces are calculated at the instantaneous position of the riser, causing the equation to be highly nonlinear. The nonlinear partial differential equation of motion is then solved numerically. Finite difference approximation code that was imbedded in ACSL software is used. The equation of motion is solved to evaluate the riser’s response to different environmental conditions and other physical parameters such as internal pressure and fluid velocity and acceleration. [S0892-7219(00)00203-X]

Newark City Subway Overhead Contact System Conversion Project

The New Jersey Transit Corporation (NJ TRANSIT) has contracted with Kinkisharyo to build new, modern light rail transit cars (LRTCs) to replace the aging fleet of President’s Conference Committee (PCC) cars operating on the Newark City Subway. The new LRTCs will draw a significantly higher electrical current than the PCCs. Maximum peak current demand of the LRTCs considered by NJ TRANSIT may exceed 1,200 A, and the existing PCCs draw maximum peak current of about 500 A. To accommodate the higher power demand of the new LRTCs, the existing overhead distribution system was evaluated. Computer simulations of the overhead distribution system indicated that the existing system is not adequate to support the future LRTC operation and that the system needs to be either upgraded or replaced. Two options were evaluated that were capable of delivering sufficient power to the new LRTCs. They were ( a) upgrading the system based on existing feeder/contact wire configuration with larger contact wire and ( b) replacing the existing system with a new two-wire simple catenary system. Finally, investigations were conducted to determine the extent and type of overhead distribution modifications required to accommodate operating the PCCs with pole collectors and LRTCs with pantographs. Design considerations included selecting catenary hardware capable of accommodating the PCC pole-collector operation and easily adapting to pantograph operation to minimize disruption of passenger service.

Study on Current Collection Characteristics and Improvement Methods of High-tension Overhead Catenary Systems.

Under the speed-up on electric railways, overhead catenary systems on narrow-gauge lines have been improved with an increase of messenger wire tension. However, contact loss ratio of pantograph is comparatively high under the heavy simple catenary or feeder messenger wire type overhead catenary. These catenary has higher tension of messenger wire. In order to investigate into the causes and to work out effective improvement methods, laboratory and field tests have been carried out. From the results thereof, it is confirmed that contact force fluctuation comes under the influence of wave reflection factor at hanger, and a hanger which has spring mechanism is found effective to improve it. It is expected that rubber damping hanger or friction damping hanger contributes to reducing the contact loss of pantograph and the wear of contact wire.

Simplified Organ Retention Functions for Physiologically Based Recycling Biokinetic Models

Recent ICRP Publications on biokinetic models show a movement from simple schematic models to more complex, physiologically-based models. Such models require considerably greater computing resources to implement than their predecessors, effectively making them inaccessible to many users. Fortunately, retention in most of the compartments of these large recycling models can be adequately approximated by the sum of a few exponential functions compatible with the simple catenary models used almost exclusively in ICRP Publication 30. An eigenvalue method is used to solve the plutonium model of ICRP Publication 67 for intakes by inhalation, ingestion, and injection. The organ retention expressions so obtained are reduced by least squares minimization to functions consisting of the sum of a few exponential terms only. These simplified functions give committed doses accurate to within 5% and activities to within 10%. A similar treatment is used to obtain simplified expressions for daily excretion rates of plutonium.

Development of Overhead Catenary System for Projected Shinkansen.

For Projected Shinkansen, it is necessary to develop an economical overhead catenary system allowing stable train operation at high-speed and meeting the transport demands. In order to develop a new overhead catenary system for this purpose, we designed a high tension simple catenary system with CS contact wire (Copper contact wire with Steel-core), and constructed this system on Tohoku Shinkansen line for operation test. During 4 years, we measured contact loss of pantograph, uplift and stress of contact wire, its maintainability including the wear of contact wire, and others. The test results so far obtained prove that its performance is as high as that of high-tension heavy compound catenary system.