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Physics Summative - MAGLEV trains
Transcript of Physics Summative - MAGLEV trains
By Jordan Widmaier
and Eric Littlewood
The Beginning: the Iron Railway
Derived from German and English mine cart technology originally using wooden rails
Principle of friction reduction by using a uniform, smooth, rigid surface
Rails provided direction = no steering needed.
Cost-effective steel production and development of the steam engine were the foundations for the modern day railway
The Modern Railway: R&D
Faster trains = more aerodynamic bodies
Introduction of aerodynamic shaping: 193
Coal-fired steam engine to diesel electric/electric engine
Electricity's power transfer advantage: max torque at min power
Superior rail, track & wheel technology development
Development of the bullet train
Max recorded speed 290km/h
Physical Limitations: Wheel/Rail Friction
We are approaching the developmental end of the conventional train
Mechanical friction between wheels and rails inhibit further considerable speed gain
Track with less resistance required for further speed increase
Solution: Magnetic Levitation
By "levitating" train body using repulsive/attractive electromagnetic fields, trains no longer physically touch track
Only resistance to train motion = air resistance
Therefore max theoretical speed of train is terminal velocity on Earth, where air resistance is the limiting factor
Magnetic Levitation: The Basics
MAGLEV Technology: The Future
Repulsive and attractive magnetic fields
One superconductor and one electromagnetic field provide field
both an attractive
to repel train up to 10cm from guideway
Alternating positive and negative electromagnetic fields on sides of guideway alternately attract and repel train body to accelerate train.
Have attained speeds in excess of 500km/h in commercial testing and in excess of 1000km/h in vacuum tube test tracks.
Require "take-off/landing gear" until levitation speed reached
Based on principle that as certain materials
approach 0 K
electrical resistance is nonexistent
, allowing electrons to flow freely through the lattice structure of the conductor. This therefore allows indefinite current flow without energy loss.
the temperature, usually approaching 0 K, where a material will transition to its superconducting state.
YBa2Cu3O7 ( Yttrium Barium Copper Oxide or YBCO) most common superconductors for HTS; reaching critical or transition temperature at 92 K.
the properties of a material approaching its transition temperature that cause it to expel any surrounding magnetic field due to the loss of electrical resistance.
Magnetic flux trapping:
the result of cooling a superconductor in the presence of a magnetic field, causing it to mirror the polarity of those magnetic fields in its superconductive state while still expelling the field (Meissner effect).
1. High temperature superconductor (HTS):
calibrated to direction of electromagnetic horizontal field, liquid nitrogen cooled
1. Horizontal levitation set:
produces magnetic field for horizontal attraction and repulsion
2. Horizontal guidance set:
along walls of guideway; produces magnetic field for horizontal propulsion
MAGLEV magnet systems
1. High temperature superconductors (HTS):
superconductors functioning at or above 77 K (temperature of liquid nitrogen)
2. Low temperature superconductors (LTS):
superconductors functioning below 4.2 K (temperature of liquid helium)
Types of superconductors
Jet and propeller accelerated train/plane hybrids
Japanese vs Chinese MAGLEV "arms race"
Chinese claim theoretical 3500km/h in vacuum tube
All function with YBCO superconductor technology
All currently in experimental phase
• Good video http://www.magnet.fsu.edu/education/tutorials/slideshows/maglev/index.html
Electromagnets are used over the traditional magnets because of the useful property that they can be turned on and off by controlling a power source.
How they work
Most basic electromagnets are made by wrapping a copper wire around a permeable material, such as iron, very tight and then an electrical current is fed through the copper wire. The flow of electrons through the copper wire closely resembles that of a normal magnet and thus, creates an magnetic field.
The tighter the coil is wrapped around the solenoid, the stronger the electromagnet becomes.
Just like any other magnet, electromagnets have poles. This means that one end of the magnet will either attract or repel the other ends of another magnet.
In magnetic levitation they use this property of repelling and attracting to construct the frictionless movement.
Attractive force system
The cause of levitation in EMS happens on the underside of the guideway. Levitation magnets are attracted to one another causing the train to be lifted upwards, at the same time gravity is acting down on the train. In order to stabilize the shuttle, a feedback loop is created to momentarily change the current to each electromagnet and stabilize the train for a smoother ride at 1.75cm above the guideway
In order to fully create a frictionless ride, guidance magnets are used on the side of the train to prevent horizontal movement.
Prevent friction that can cause a slower speed, unwanted noise, and at high speeds lots of damage to the track and train.
Used to help "guide" the train around gradual turns throughout the ride.
Shanghai Maglev Train
This is the first commercial maglev in the world and cost 1.2 billion to make. It currently reaches max speeds of 431km/h
How Guideways Work
A guideway is one long series of magnetized coils that span the distance that the train will be traveling, just like a traditional train track
Propulsion occurs once levitation has stabilized.
Power is supplied to the system that then turns on a series of electromagnets in the guideway. This electromagnetic system is designed that
when powered on, the magnets in the train begin to be attracted to oposite ends and repelled by like ends to move the train down the guideway.
Because they can harness both forces of the magnets, very high speeds can be obtain in a very short amount of time. not to mention there is no friction because the whole system levitates.