[Back]

G. Liedl, D. Schuöcker et al.:
"Laser induced ignition of gasoline direct injection engines";
Talk: GCL/HPL, Prague (invited); 08-30-2004 - 09-03-2004; in: "Proceedings SPIE", SPIE, 5777 (2004), ISBN: 0-8194-5760-4; 955 - 960.

A q-switched Nd:YAG laser as well as an excimer laser with an
unstable resonator have been used for ignition of combustion
processes. Following first experiments with a combustion bomb a
gasoline direct injection engine has been modified for laser
ignition by installation of a focusing element and a beam entrance
window. It was possible with the q-switched Nd:YAG laser which
delivers short pulses with a duration of less than 6 ns to ignite
the engine for several 100 hours without problems. Compared to
conventional spark ignition, laser ignition allows a more flexible
choice of the ignition location inside the combustion chamber with
the possibility to ignite even inside the fuel spray. Measurements
of fuel consumption and emissions prove that laser ignition has
important advantages compared to conventional spark ignition
systems. Experiments with the direct injection engine have been
carried out at the fundamental wavelength of the Nd:YAG laser as
well as with a frequency doubled system. No differences in the
minimal pulse energy needed for ignition could be found, since the
minimal pulse energy for ignition is mainly determined by the
ablation thresholds of combustion deposits at the surface of the
window to the combustion chamber. Such combustion deposits reduce
the transparency of the window where the laser beam enters the
combustion chamber and a "self-cleaning" mechanism of the window
by ablation is essential for successful operation. Experiments
show that above a certain threshold intensity of the laser beam at
the window even highly polluted surfaces could be cleaned with the
first laser pulse which is important for operation in real-world
engines. Theoretically calculated energy values for laser ignition
are much lower since such mechanisms are usually not considered.
Power and space requirements on possible future developments of
laser ignition systems are discussed briefly. Several concepts for
laser ignition, like diode-pumped solid state lasers (DPSS) with
and without fiber coupling are presented and chances on
realization are discussed.

http://aleph.ub.tuwien.ac.at/F?base=tuw01&func=find-c&ccl_term=AC04968822

http://publik.tuwien.ac.at/files/pub-mb_2880.pdf