25-08-2014, 09:55 AM
LASER IGNITION SYSTEM IN IC ENGIN
LASER.pptx (Size: 1.54 MB / Downloads: 16)
INTRODUCTION
An alternative solution to standard spark plug is the use of pulsed laser, focused to create plasma, representing the laser ignition.
Laser ignition, or laser-induced ignition, is the process of starting combustion by the stimulus of a laser light source.
Spark creation due to the local deposition of energy
Ignition itself based on a positive balance between the deposited energy and the losses
What is a Laser?
A laser is a device that emits electromagnetic radiation through a process of optical amplification based on the stimulated emission of photons.
The term ‘laser’ is Light Amplification by Stimulated Emission of Radiation
The emitted laser is unique in its high degree of spatial and temporal coherence.
Spatial Coherence means a fixed phase relationship between the electric fields at different locations across the beam. Typically it is expressed through the output being a narrow beam which is diffraction-limited, also known as a "pencil beam." Laser beams can be focused to very tiny spots, achieving a very high irradiance.
Temporal coherence means a strong correlation between the electric fields at one location, but different times.
Types of Lasers
Gas
A Helium-Neon (HeNe) used mostly for holograms such as laser printing.
Chemical
Lasers that obtain their energy through chemical reactions. Used mostly for weaponry.
Dye
Uses organic dye as the lasting medium, usually in the form of a liquid solution. Used in medicine, astronomy, manufacturing, and more.
Solid-state
Uses a gain medium that is a solid (rather than a liquid medium as in dye or gas lasers). Used for weaponry
Semiconductor
Also known as laser diodes, a semiconductor laser is one where the active medium is a semiconductor similar to that found in a light-emitting diode.
Applications include telecommunication and medicine
How Laser Ignition Works
The laser ignition system has a laser transmitter with a fiber-optic cable powered by the car’s battery. It shoots the laser beam to a focusing lens that would consume a much smaller space than current spark plugs. The lenses focus the beams into an intense pinpoint of light, and when the fuel is injected into the engine, the laser is fired and produces enough energy (heat) to ignite the fuel.
Advantages of Laser Ignition
Arbitrary positioning of the ignition plasma
Absence of quenching effects
Absence of erosion effects
Precise ignition timing
Simpler regulation of the ignition energy
Easy possibility of multipoint ignition
Disadvantages
high system costs
concept proven, but no commercial system available yet.
CONCLUSION
Plasma propagates towards the incoming laser beam
Plasma had the maximum emission peak 30 ns after the laser was fired and laser plasma UV-emission persisted for about 80 ns
Minimum laser pulse energy for ignition is decreases with increasing initial pressure
The time of pressure rise in case of laser ignition is shorter than the spark ignition