60043 - High-Temperature Ignition Kinetics of Gas Turbine Lubricating Oils 

Lubricant ignition is a highly undesirable event in any mechanical system. Gas turbines in particular require lubrication in high-temperature environments, increasing the possibility of lubricant auto-ignition. Understanding this event and how to prevent it requires a fundamental understanding of the ignition kinetics of these lubricants. However, minimal work has been conducted to investigate the auto-ignition properties of gas turbine lubricants. To this end, using a recently established spray injection scheme in a shock tube, a gas turbine lubricant (Mobil DTE 732) spray has been subjected to high-temperature post-reflected-shock conditions. The ignition process of the lubricant spray is then monitored using a CH* chemiluminescence optical diagnostic at the sidewall location of the shock tube. A combination of an extended shock-tube driver and driver gas tailoring were utilized to observe ignition for a wide range of temperatures and ignition delay times (τ_ign) at near atmospheric pressures. A clear, two-stage-ignition process was observed for all tests, and both first and second stage ignition delay times are compared and discussed. Additionally, a comparison between the second-stage τ_ign results and τ_ign literature data for kerosene was performed. Chemical kinetic modeling was also performed using a lubricant surrogate suggested in the literature to test the surrogate’s applicability and elucidate a discussion of compounds and reactions most important to lubricant ignition.