2011-laser ignition for internal combustion engines

8/12/2019 2011-Laser Ignition for Internal Combustion Engines

1/13

Laser Ignition for

Internal Combustion Engines

Nick DeMarco

PHYS 43Modern Physics

Dr. Younes Ataiiyan

Semester Project

SRJC

Dean Clewis


2/13

So, what is a ?

Generally, most of us

think of lasers likethis, which isnt

entirely wrong


3/13

What is a Laser?

A laseris a device that emits electromagnetic radiation through a process of optical

amplification based on the stimulated emission of photons. The term laser is an acronym for 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 differentlocations across the beam. Typically it is expressed through the output being a narrowbeam which is diffraction-limited, also known as a "pencil beam." Laser beams can befocused 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.

Electric field distribution around

the focus of a Gaussian laser

beam with perfect spatial and

temporal coherence.

A laser beam with high

spatial coherence, but poor

temporal coherence

A laser beam with poor

spatial coherence, but high

temporal coherence.


4/13

Lasers are monochromatic, meaning they are very orderly forms of light that have only one

wavelength and one direction.

It all starts with the electrons. By sending energy to a system we can achieve what is known

aspopulation inversion. This means that there are more electrons in the excited states than

those in the lower energy states. As one electron releases energy (a photon), the other

electrons strangely seem to communicate with each other and also begin releasing photons.

This chain reaction of releasing photons is called stimulated emission. The problem now is

that these photons are released in random directions. In order to make sure this energy is allforced in the same direction, mirrors are strategically laced within a laser to direct the

photons. The photons are directed by bouncing back and forth between the mirrors, hitting

each other and causing more stimulated emission.

So, by having:

- Population Inversion- Stimulated Emission

- Strategic Planting of Mirrors

We get:

- Monochromatic , Directional, and Coherent light.

How does a Laser work?


5/13

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


6/13

Standard Spark Plug Ignition in an

Internal Combustion Engine Current internal combustion gasoline engines use spark plugs to ignite the air/fuel

mixture in each cylinder (located at the top of the combustion chamber).


7/13

Laser Ignition System for an Internal

Combustion Engine

Laser ignition will replace the spark plug seen in current gasoline engines.


8/13


9/13

How Laser Ignition Works The laser ignition system has a laser transmitter with a fiber-optic cable powered by the cars

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.

Below is a diagram of the laser arrangement:


10/13

Why Laser Ignition? Regulations on NOx emissions are pushing us toward leaner air/fuel ratios

(higher ratio of air to fuel).

These leaner air/fuel ratios are harder to ignite and require higher ignitionenergies. Spark plugs can ignite leaner fuel mixtures, but only byincreasing spark energy. Unfortunately, these high voltages erode sparkplug electrodes so fast, the solution is not economical. By contrast, lasers,which ignite the air-fuel mixture with concentrated optical energy, have noelectrodes and are not affected.

Natural gas is more difficult to ignite than gasoline dueto the strong carbon to hydrogen bond energy.

Lasers are monochromatic, so it will be much easier to ignite naturalgases and direct the laser beam to an optimal ignition location.

Because of the requirement for an increase in ignition energy, spark plug lifewill decrease for natural gas engines.

Laser spark plug ignition system will require less power than traditionalspark plugs, therefore outlasting spark plugs.

Ignition sites for spark plugs are at a fixed location at the top of the combustionchamber that only allows for ignition of the air/fuel mixture closest to them.

Lasers can be focused and split into multiple beams to give multipleignition points, which means it can give a far better chance of ignition.


11/13

Why Laser Ignition? (continued) Lasers promise less pollution and greater fuel efficiency, but making small, powerful lasers

has, until now, proven hard. To ignite combustion, a laser must focus light toapproximately 100 gigawatts per square centimeter with short pulses of more than 10millijoules each.

Japanese researchers working for Toyota have created a prototype laser that brings laserignition much closer to reality. The laser is a small (9mm diameter, 11mm length) highpowered laser made out of ceramics that produces bursts of pulses less than a

nanosecond in duration.

The laser also produces more stable combustion so you need to put less fuel into thecylinder, therefore increasing efficiency.

Optical wire and laser setup is much smaller than the current spark plug model, allowing

for different design opportunities.

Lasers can reflect back from inside the cylinders relaying information such as fuel type andlevel of ignition creating optimum performance.

Laser use will reduce erosion.


12/13

Future Research Needs and

Shortcomings

Cost Concept proven, but no commercial system yet available.

Stability of optical window

Beam Delivery/Laser induced optical damage

Particle Deposits

Intelligent control

Laser Distribution

Multiple pulse ignition

Multiple point ignition

Single Point Ignition: Timing optimization (phasing) vs Thermal Efficiency

NOx tradeoffs

Knock margin

Multipoint Ignition: Higher flame speed may provide additional knock margin

as well as a higher burn rate.

Multipulse Ignition: May provide improved ignition, leaner combustion, and lower emissions.

May provide a way to circumvent beam delivery issue.


13/13

Acknowledgements http://www.laserist.org/Laserist/showbasics_laser.html

http://www.dtic.mil/cgi-

bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA427076

http://www.maik.rssi.ru/full/lasphys/05/7/lasphys7_05p947full.pdf

http://www.carbontrust.co.uk/SiteCollectionDocuments/Grant%20Funded

%20Projects/075,%20076,%20077%20projects/076-

207%20University%20of%20Liverpool%20final%20PDF%20locked.pdf

http://www.laserist.org/Laserist/showbasics_laser.html

http://affleap.com/laser-ignition-system-to-replace-spark-plugs/