Investigation on the Aerodynamic Efficiency of Braking Spoiler for High Speed Train Applications

2020 ◽  
pp. 2150009
Author(s):  
M. Vikraman ◽  
J. Bruce Ralphin Rose ◽  
S. Ganesh Natarajan
Keyword(s):  
High Speed ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
High Speed Train ◽  
Passenger Cars ◽  
High Speed Rail ◽  
Braking Performance ◽  
Simulation Tools ◽  
Drag Forces ◽  
Differential Drag

The demand for high speed rail networks is rapidly increasing in developing countries like India. One of the major constraints in the design and implementation of high speed train is the braking efficiency with minimum friction losses. Recently, the aerodynamic braking concept has received good attention and it has been incorporated for high speed bullet trains as a testing phase. The braking performance is extremely important to ensure the passenger safety specifically for the trains moving at more than 120[Formula: see text]km/h. In this paper, an Indian train configuration WAP7 (wide gauge AC electric passenger, Class 7) has been assumed with the locomotive and one passenger car. Aerodynamic braking system design is done by opening a spoiler over the train to amplify the aerodynamic drag at high speeds. The magnitude of braking force depends on the position and orientation of the braking spoiler. It creates differential drag forces at various deflection angles to decelerate the trains instantaneously in proportion to the running speeds. Drag created by the braking spoiler is observed numerically with the help of CFD simulation tools for further validation through wind tunnel experiments. Striking aerodynamic results are obtained with and without braking spoilers on the passenger cars and the spoiler at 40[Formula: see text]–50[Formula: see text] orientation makes greater drag coefficient as compared to the other angles.

scholarly journals CFD Simulation of a Hyperloop Capsule Inside a Low-Pressure Environment Using an Aerodynamic Compressor as Propulsion and Drag Reduction Method

2021 ◽  
Vol 11 (9) ◽  
pp. 3934
Author(s):  
Federico Lluesma-Rodríguez ◽  
Temoatzin González ◽  
Sergio Hoyas
Keyword(s):  
Shock Waves ◽  
Power Consumption ◽  
High Speed ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Flow Behavior ◽  
Critical Conditions ◽  
Vehicle Speed ◽  
Blockage Ratio ◽  
The Cost

One of the most restrictive conditions in ground transportation at high speeds is aerodynamic drag. This is even more problematic when running inside a tunnel, where compressible phenomena such as wave propagation, shock waves, or flow blocking can happen. Considering Evacuated-Tube Trains (ETTs) or hyperloops, these effects appear during the whole route, as they always operate in a closed environment. Then, one of the concerns is the size of the tunnel, as it directly affects the cost of the infrastructure. When the tube size decreases with a constant section of the vehicle, the power consumption increases exponentially, as the Kantrowitz limit is surpassed. This can be mitigated when adding a compressor to the vehicle as a means of propulsion. The turbomachinery increases the pressure of part of the air faced by the vehicle, thus delaying the critical conditions on surrounding flow. With tunnels using a blockage ratio of 0.5 or higher, the reported reduction in the power consumption is 70%. Additionally, the induced pressure in front of the capsule became a negligible effect. The analysis of the flow shows that the compressor can remove the shock waves downstream and thus allows operation above the Kantrowitz limit. Actually, for a vehicle speed of 700 km/h, the case without a compressor reaches critical conditions at a blockage ratio of 0.18, which is a tunnel even smaller than those used for High-Speed Rails (0.23). When aerodynamic propulsion is used, sonic Mach numbers are reached above a blockage ratio of 0.5. A direct effect is that cases with turbomachinery can operate in tunnels with blockage ratios even 2.8 times higher than the non-compressor cases, enabling a considerable reduction in the size of the tunnel without affecting the performance. This work, after conducting bibliographic research, presents the geometry, mesh, and setup. Later, results for the flow without compressor are shown. Finally, it is discussed how the addition of the compressor improves the flow behavior and power consumption of the case.

On the correlation between aerodynamic drag and wake flow for a generic high-speed train

2021 ◽  
Vol 215 ◽  
pp. 104698
Author(s):  
Xiao-Bai Li ◽  
Xi-Feng Liang ◽  
Zhe Wang ◽  
Xiao-Hui Xiong ◽  
Guang Chen ◽  
...  
Keyword(s):  
High Speed ◽  
Aerodynamic Drag ◽  
Wake Flow ◽  
High Speed Train

scholarly journals The Effect of Pendolino high-speed rail on the structure of buildings located in the proximity of railway tracks

2016 ◽  
Vol 21 (1) ◽  
pp. 231-238
Author(s):  
K. Grębowski ◽  
Z. Ulman
Keyword(s):  
Dynamic Analysis ◽  
High Speed ◽  
Building Structure ◽  
High Speed Train ◽  
High Speed Rail ◽  
Railway Tracks ◽  
High Speed Trains ◽  
Railway System ◽  
The Subject ◽  
The Impact

Abstract The following research focuses on the dynamic analysis of impact of the high-speed train induced vibrations on the structures located near railway tracks. The office complex chosen as the subject of calculations is located in the northern part of Poland, in Gdańsk, in the proximity of Pendolino, the high speed train route. The high speed trains are the response for the growing needs for a more efficient railway system. However, with a higher speed of the train, the railway induced vibrations might cause more harmful resonance in the structures of the nearby buildings. The damage severity depends on many factors such as the duration of said resonance and the presence of additional loads. The studies and analyses helped to determinate the method of evaluating the impact of railway induced vibrations on any building structure. The dynamic analysis presented in the research is an example of a method which allows an effective calculation of the impact of vibrations via SOFISTIK program.

Probabilistic Analysis of Flying Ballast on High-Speed Rail Lines

2017 ◽  
Author(s):  
Jieyi Deng ◽  
Guoqing Jing ◽  
Xiang Liu
Keyword(s):  
Risk Factors ◽  
High Speed ◽  
Safety Concern ◽  
Rolling Stock ◽  
Probabilistic Assessment ◽  
High Speed Train ◽  
Modeling Framework ◽  
High Speed Rail ◽  
Rail Systems ◽  
Ballasted Track

Safety is a top priority for the development of worldwide high-speed rail systems. Ballast flying is a particular safety concern when a high-speed train is traveling above a certain speed on the ballasted track. Displaced ballast particles from the track may cause damages to rolling stock, as well as the track infrastructure and wayside structures close to the sides of way. The objective of this research is to develop a probabilistic modeling framework to estimate the probability of ballast flight on specific segments or routes, accounting for several principal risk factors. Based on the probabilistic assessment, we propose a methodology to quantify the probability of flying ballast under certain scenarios. The methodology can be further developed, ultimately enabling a normative risk assessment for flying ballast risk management.

Experimental Studies on Aerodynamic Characteristics of Pantograph System According to the Pantograph Cover Configurations for High Speed Train

2011 ◽  
Author(s):  
Yeongbin Lee ◽  
Minho Kwak ◽  
Kyu Hong Kim ◽  
Dong-Ho Lee
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Aerodynamic Force ◽  
Experimental Studies ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Experimental Models ◽  
High Speed Train ◽  
Drag And Lift

In this study, the aerodynamic characteristics of pantograph system according to the pantograph cover configurations for high speed train were investigated by wind tunnel test. Wind tunnel tests were conducted in the velocity range of 20∼70m/s with scaled experimental pantograph models. The experimental models were 1/4 scaled simplified pantograph system which consists of a double upper arm and a single lower arm with a square cylinder shaped panhead. The experimental model of the pantograph cover is also 1/4 scaled and were made as 4 different configurations. It is laid on the ground plate which modeled on the real roof shape of the Korean high speed train. Using a load cell, the aerodynamic force such as a lift and a drag which were acting on pantograph system were measured and the aerodynamic effects according to the various configurations of pantograph covers were investigated. In addition, the total pressure distributions of the wake regions behind the panhead of the pantograph system were measured to investigate the variations of flow pattern. From the experimental test results, we checked that the flow patterns and the aerodynamic characteristics around the pantograph systems are varied as the pantograph cover configurations. In addition, it is also found that pantograph cover induced to decrease the aerodynamic drag and lift forces. Finally, we proposed the aerodynamic improvement of pantograph cover and pantograph system for high speed train.

Moving element analysis of discretely supported high-speed rail systems

2017 ◽  
Vol 232 (3) ◽  
pp. 783-797 ◽  
Author(s):  
Jian Dai ◽  
Kok Keng Ang ◽  
Minh Thi Tran ◽  
Van Hai Luong ◽  
Dongqi Jiang
Keyword(s):  
High Speed ◽  
Railway Track ◽  
High Speed Train ◽  
Element Analysis ◽  
High Speed Rail ◽  
Mass System ◽  
Rail System ◽  
Rail Systems ◽  
Track System ◽  
The Difference

In this paper, a computational scheme in conjunction with the moving element method has been proposed to investigate the dynamic response of a high-speed rail system in which the discrete sleepers on the subgrade support the railway track. The track foundation is modeled as a beam supported by uniformly spaced discrete spring-damper units. The high-speed train is modeled as a moving sprung-mass system that travels over the track. The effect of the stiffness of the discrete supports, train speed, and railhead roughness on the dynamic behavior of the train–track system has been investigated. As a comparison, the response of a continuously supported high-speed rail system that uses a foundation stiffness equivalent to that of a discretely supported track has been obtained. The difference in results between the “equivalent” continuously supported and the discretely supported high-speed rails has been compared and discussed. In general, the study found that a high-speed train that travels over a discretely supported track produces more severe vibrations than that travels over a continuously supported track of equivalent foundation stiffness.

scholarly journals A Numerical Study of the Screening Effectiveness of Open Trenches for High-Speed Train-Induced Vibration

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Chih-hung Chiang ◽  
Pei-hsun Tsai
Keyword(s):  
Poisson’S Ratio ◽  
High Speed ◽  
Numerical Study ◽  
Cutoff Frequency ◽  
Poisson's Ratio ◽  
High Speed Train ◽  
High Speed Rail ◽  
Train Speed ◽  
Open Trench ◽  
Screening Effectiveness

This study used the 2D boundary element method in time domain to examine the screening effectiveness of open trenches on reducing vibration generated by a high-speed train. The parameters included configurations of the trench, train speed, the distance between the source and the trench, and the Poisson’s ratio of the soil. A reducing displacement level (in dB scale) was defined and used to evaluate the screening effectiveness of a wave barrier. The maximal reducing displacement level reached 25 dB when an open trench was used as a wave barrier. The depth of an open trench is a main influential parameter of screening effectiveness. The cutoff frequency of the displacement spectrum increases with decreasing trench depth. The maximal screening effectiveness occurs when the depth is 0.3-0.4 Rayleigh wavelength. Using an open trench as a wave barrier can reduce 10–25 dB of vibration amplitude at frequencies between 30 and 70 Hz. A considerable increase in screening effectiveness of the open trench was observed from 30 to 70 Hz, which matches the main frequencies of vibration induced by Taiwan High Speed Rail. The influence of trench width on screening effectiveness is nonsignificant except for frequencies from 30 to 40 Hz. Poisson’s ratio has various effects on the reduction of vibration at frequencies higher than 30 Hz.

Who Rides the High Speed Rail in the United States: The Acela Express Case Study

2010 ◽  
Author(s):  
Zhenhua Chen
Keyword(s):  
High Speed ◽  
The United States ◽  
External Factors ◽  
Least Square ◽  
High Speed Train ◽  
High Speed Rail ◽  
Rail Network ◽  
Policy Suggestions ◽  
Internal And External Factors

In this study, we focus on the Acela Express, and try to find out how selected internal and external factors affect the Acela Express’s ridership. A two-stage least square regression model is introduced in order to eliminate the endogeneity problem caused by price and ridership. Also the Cochrane-Orcutt Procedure is adopted to solve autocorrelation. The result shows that ticket price and train on-time performances, which are used to being thought as important factors affect ridership become insignificant, while other factors like employment of business and professional in the Northeast Corridor areas have higher influence on high speed train ridership. The broader objective of this research is to provide policy suggestions for building of an efficient high-speed rail network that can both be profitable and solve practical problems that the contemporary transportation system faces.

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