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 (τign) 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 τign results and τign 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.

High-Temperature Ignition Kinetics of Gas Turbine Lubricating Oils

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

Turbo Expo 2021

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