Effect of ignition location on the in-process removal of combustion deposits from the output window of a gas turbine laser ignition system

The effect of ignition location on the effectiveness of combustion deposit removal from the reverse side of an optical window in a laser ignition system for use in gas turbines is presented. Such deposits consist of carbon and other by-products which accumulate on the walls of the chamber as a result of incomplete combustion. In laser based ignition systems this accumulation of combustion deposits has the potential to reduce the transmissive properties of the output window required for transmission of the laser radiation into the combustion chamber, adversely affecting the likelihood of successful ignition. In this work, a full empirical study into the in-process removal of combustion deposits from the reverse side of the optical window in a laser ignition system using a Q-switched Nd:YAG laser is presented, with an emphasis on the effect of ignition location on the effectiveness of combustion deposit removal. In addition, the mechanism of deposit removal is discussed.

► Laser ignition system output window cleaning investigated.
► In-process removal of carbon layer from reverse side of output window examined.
► Dependence of effectiveness of in-process removal on ignition location established.
► Ignition location range extended through application of dual pulse technique.