Abstract

This work details a study of laser ignition in a low pressure combustion test rig, representative of an
industrial gas turbine (SGT-400, Siemens Industrial Turbomachinery Ltd.) and for the first time
investigates the effect of air mass flow rate on combustion characteristics at air/fuel ratios at the lean
burn limit.Boththeleanburnlimitandtimetakentolightareessentialindeterminingthesuitabilityof
a specified air/fuel ratio, especially in multi-chamber ignition applications. Through extension of the lean
burn limit and reduction of the time taken to light, the operating window for ignition with regards to the
air/fuel ratio can be increased, leading to greater reliability and repeatability of ignition. Ignition of a
natural gas and air mixture at atmospheric pressure was conducted using both a standard high energy
igniter and a laser ignition system utilizing a Q-switched Nd:YAG laser source operating at 1064 nm
wavelength. A detailed comparison of the lean burn limit and time taken to light for standard ignition
and laser ignition is presented.