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.

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 Vacuum magnetic levitation transport: definition of optimal characteristics

2016 ◽  
Vol 2 (3) ◽  
pp. 18-35 ◽  
Author(s):  
V M Fomin ◽  
V I Zvegintsev ◽  
D J Nalivaichenko ◽  
Y A Terent’ev
Keyword(s):  
High Speed ◽  
Magnetic Levitation ◽  
Aerodynamic Drag ◽  
Low Cost ◽  
Balance Of Power ◽  
Cost Of Energy ◽  
Wide Circle ◽  
Definition Of ◽  
Working Parameters ◽  
The Cost

Known to a wide circle of specialists of the transport, the concept of "Evacuated Тube Тransport Technology" (ET3) [1] is an energy efficient complex magnetic levitation, vacuum and superconducting technology for high-speed ground transportation. The concept is presented as the most effective solution to problem increase the speed and capacity of the transport system c is acceptable the cost of moving passengers and cargo, and low cost of energy. To determine the optimal ranges of working parameters of the considered transportation system the analysis of the characteristics of the rarefied environment. Based on considerations of balance of power the cost of maintaining the vacuum in the system and to overcome aerodynamic drag throughout the speed range of the vehicle (TC) (500÷6500 km/h) it is shown that the lower bound of the optimal depth of vacuum to the vacuum environment, for the vehicle to relatively low speeds, is 25÷80 PA. For vehicles with speeds close to the maximum I would like to have the pressure of 1 PA or less.

Numerical investigation of the pressure and friction resistance of a high-speed subway train based on an overset mesh method

2020 ◽  
pp. 095440972095129
Author(s):  
Zhen Liu ◽  
Guang Chen ◽  
Dan Zhou ◽  
Zhe Wang ◽  
Zijian Guo
Keyword(s):  
Turbulence Model ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Expansion Wave ◽  
Formation Mechanisms ◽  
Blockage Ratio ◽  
Friction Drag ◽  
Mach Wave ◽  
Friction Resistance ◽  
Mesh Method

The aerodynamic resistance induced by a high-speed metro train entering and operating in a tunnel with a speed of 120 km/h is simulated using a three-dimensional, compressible turbulence model. An overset mesh method is adopted to solve the moving boundary problem, and the flow field around the train is simulated with a k-omega SST turbulence model to obtain accurate stress values at the walls. The selected model is verified with experimental and numerical data from the literature. Then, numerical simulations are performed to analyse the formation mechanisms of the pressure and friction drags. The aerodynamic drag basically stabilizes after the expansion wave passes the train head. The results reveal that the variations in friction resistance are related to the direction of the Mach wave, and this trend differs from that observed for pressure resistance. Mach wave influences the velocity where it passes, and further influences the friction drag. Result shows that friction drag of the train increases when encounter with compression wave propagated from the front or expansion wave propagated from the back, and decreases otherwise. The effects of the blockage ratio on the maximum and average pressure and friction resistance values of each train section are evaluated based on fitting functions. The predicted aerodynamic drag varies with the blockage ratio and for each train section, and the results are summarized and compared with predictions and experimental data from the literature. The variations in tunnel resistance and the overall trend are in good agreement with the previous results. Therefore, the findings presented in this study may provide a reference for the design of high-speed subway tunnels.

Power Consumption Analysis of High-Speed Train’s Brake Discs

2013 ◽  
Vol 765-767 ◽  
pp. 120-124
Author(s):  
Xiao Yu Zhu ◽  
Jian Yong Zuo
Keyword(s):  
Power Consumption ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Brake Disc ◽  
High Speed Train ◽  
Air Inlet ◽  
Resistance Torque ◽  
Brake Discs ◽  
Rotational Parts ◽  
Traction Power

Apart from the aerodynamic drag produced by transitional motion of high-speed train, the rotational parts of the train, especially the ventilated discs mounted on axles, would also cause resistance torques due to air pumping effect, which consume traction power. In this paper the train running process is divided into traction, uniform running and braking three phases, then the power consumed by the brake discs as well as the proportion of which in total traction or braking power during the three periods is calculated based on kinetic energy theorem. The results indicate that, during traction and uniform running period, the power consumption of brake discs shares 2.84% and 12.87% of total traction power, and in brake stage, the proportion is 0.78%. What is more, in the uniform running phase, the proportion of brake discs power consumption caused by resistance torque can reach to 7.68%. If the air inlet of brake disc is blocked during traction and uniform running period to weaken air pumping effect, the useless power consumption can be effectively reduced and the traction efficiency can be improved.

Investigation on Aerodynamic Drag Reduction of Commercial Truck Based on External Styling of Cab

2013 ◽  
Vol 307 ◽  
pp. 186-191 ◽  
Author(s):  
Peng Guo ◽  
Xing Jun Hu ◽  
Yun Yun Zhu ◽  
Qiang Fu ◽  
Xin Yu Wang ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Wind Tunnel ◽  
Drag Reduction ◽  
Energy Saving ◽  
High Speed ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Impact Mechanism ◽  
Aerodynamic Drag Reduction ◽  
The Impact

Aerodynamic drag reduction of commercial truck at high speed is one of the important ways to reduce its energy consumption. CFD simulation and wind tunnel tests are performed on a kind of commercial truck, to study the influence of the cab shape and different kinds of guide cowls on aerodynamic drag, and the impact mechanism was also analyzed. It shows that the cab shape will make great contributions to the aerodynamic drag while the truck travelling, and through improving the shape of cab, guiding the air flow passed, it can effectively reduce the aerodynamic drag and achieve energy saving.

Influence of a high-speed train passing through a tunnel on pantograph aerodynamics and pantograph–catenary interaction

2016 ◽  
Vol 231 (2) ◽  
pp. 198-210 ◽  
Author(s):  
Ruiping Li ◽  
Weihua Zhang ◽  
Zhou Ning ◽  
Binbin Liu ◽  
Dong Zou ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Contact Forces ◽  
Blockage Ratio ◽  
High Speed Train ◽  
Aerodynamic Forces ◽  
Current Collection ◽  
Uplift Forces

Aerodynamics of trains running inside tunnels change more significantly in comparison with open air scenarios. It has been confirmed that the lateral vibration as well as the aerodynamic drag of the trains is increased and the micro-pressure wave is produced at the tunnel exit when the trains are passing through tunnels. The aim of this article is to explore the impact of a high-speed train passing through a tunnel on the pantograph aerodynamics and the dynamic behavior of the pantograph–catenary interaction. The aerodynamic forces acting on the pantograph are investigated thoroughly by extensive numerical simulations as well as systematic field tests. To investigate the effects of the aerodynamic forces of pantograph on the quality of current collection, the numerical simulations of the pantograph–catenary dynamic interaction are conducted with our proposed model, taking into consideration the action of the aerodynamic uplift forces obtained by the numerical simulations on the pantograph. Then, a series of numerical simulations are also carried out to analyze the effects of the train speed and the blockage ratio on the aerodynamic uplift forces of the pantograph, on the contact forces, as well as on the displacement of the contact wire, while the train is passing through a tunnel. The results reveal that compared with the open air scenarios, the aerodynamic drag and uplift forces of the pantograph, the mean value of the contact force and the displacement level of the registration arm can considerably increase as the train runs inside a tunnel. Moreover, the statistical values of the contact forces and the displacement level of the contact wire become larger while the train is passing through the tunnel at different speeds. On the other hand, the quality of current collection decreases with the increasing of the blockage ratio.

Numerical Investigation of Aerodynamic Drag on Vacuum Tube High Speed Train

2013 ◽  
Author(s):  
Sreeja Bibin ◽  
Sujay Kumar Mukherjea
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Aerodynamic Drag ◽  
Vacuum Pressure ◽  
Navier Stokes ◽  
Optimum Shape ◽  
Blockage Ratio ◽  
High Speed Train ◽  
Vacuum Tube ◽  
Turbulent Modeling

This work involves numerical simulations based on finite volume method to study the effects of different factors on the aerodynamic drag on a vacuum tube train running at subsonic and transonic speeds in a partially vacuum tunnel. Investigation includes the study of the effects of the shapes of head, tail, vacuum pressure and also blockage ratio of the tunnel on aerodynamic drag on a high speed train. The simulation is performed by using fluent software. Two dimensional, axisymmetric, compressible Navier-Stokes equations were solved by using k-ε turbulent modeling. Five different blockage ratios at five different speeds of the train have been considered. The simulated results show that, the blockage ratio and different working vacuum pressure significantly affects the aerodynamic drag of the train in a tunnel. Investigations with respect to different shapes of the head as well as that of the tail indicate the optimum shape for minimum drag.

scholarly journals Traffic Speed Rule Violation Detection System

2021 ◽  
pp. 536-541
Author(s):  
Ms. Rajaswi Borkar ◽  
Ms. Saloni Kadu ◽  
Ms. Saloni Kolpekwar ◽  
Mr. Dhanraj Parate ◽  
Mr. Saranju Bule ◽  
...  
Keyword(s):  
Police Officers ◽  
High Speed ◽  
Detection System ◽  
Cost Effective ◽  
Road Accident ◽  
Speed Limit ◽  
Vehicle Speed ◽  
Traditional Methods ◽  
Violation Detection ◽  
The Cost

Research has shown that the highest rates of road accident are caused by high-speed vehicles. In an attempt to mitigate this problem, the authority has specified speed limits on the roads in order to regulate the speed of vehicles. To successfully enforce the speed limit law, a mechanism for monitoring a vehicle speed is required. There are numerous measures in use for detecting and monitoring the speed limit violators. Some of these methods include the use of speed cameras, radar, loop detector, police officers, and many more. These traditional methods are not effective due to their setbacks, which ranges from the cost of acquiring equipment, increase labor and manpower, and inadequacy of monitoring. As such, a simple, cost effective and easily deployed speed detection technique that can overcome the shortcomings of the traditional methods imperative. In this paper, we proposed an automatic speed violation detection. The proposed system is cost effective and user centered.

ANALISA PERBANDINGAN DALAM RANGKA PEMILIHAN BEBERAPA IP UPSTREAM PROVIDER DI PT. INDOSAT

2018 ◽  
Vol 4 (1) ◽  
pp. 57
Author(s):  
Yuli Anwar ◽  
Dahlar .
Keyword(s):  
Business Strategy ◽  
High Speed ◽  
Human Life ◽  
Sustainable Growth ◽  
The Internet ◽  
Network Service Provider ◽  
High Speed Data ◽  
Telecommunications Services ◽  
The Cost ◽  
Internet Network

Abstract. One of the advances in information technology that now has changed the outlook and human life, business process and business strategy of an institution is the internet. The internet is a very large networks that connected to computers and serves throughout the world in one centralized network. With the internet we can access data and information anytime and anywhere.    As one provider of high-speed data communications services and the pioneer of the internet network service provider in Indonesia that provides integrated services, as well as one of the pioneer development of internet services that provide extensive services in the building and apply it throughout Indonesia. Indosat ready to seize opportunities for sustainable growth of business spectrum are still sprawling Indonesia.    Therefore, Indosat continues to focus on the development of increased efforts to provide the best service for customers of Indosat. Indosat will continue to develop and expand network coverage and a larger investment that the company will achieve excellence in the field of integrated telecommunications services.    Ranking by region of the IP Providers can be seen by grouping IP Providers, and management over IP Providers prefer to choose providers based on where it orginates as an example for the region of the U.S if it will be preferred providers that come from U.S. providers.With the commencement of the internet network optimization start early in 2008 with the selection of the appropriate IP Upstream Provider criteria, it is up to date according to data obtained from Indosat, seen any significant changes to the cost of purchasing capacity of the IP Upstream.    Based on the data obtained that until Q3 or September 2008, the number of IP Upstream Providers that previously there were 20 to 10 IP Upstream Provider, IP Transit Price total decrease of 11% to the price of IP Transit Price / Mbps there is a decrease of 78%, while from the capacity bandwith an increase of 301% capacity from 2008.

Sign in / Sign up

Export Citation Format

Share Document