The Measurement and Prediction of Gaseous Hydrocarbon Fuel Auto-Ignition Delay Time at Realistic Gas Turbine Operating Conditions

Abstract

Auto-ignition delay time measurements have been attempted for a variety of gaseous fuels on a flow rig at gas turbine relevant operating conditions. The residence time of the flow rig test section was approximately 175 ms. A chemical kinetic model has been used in Senkin, one of the applications within the Chemkin package, to predict the auto-ignition delay time measured in the experiment. The model assumes that chemistry is the limiting factor in the prediction and makes no account of the fluid dynamic properties of the experiment. Auto-ignition delay time events were successfully recorded for ethylene at approximately 16 bar, 850K and at equivalence ratios between 2.6 and 3.3. Methane, natural gas and ethylene (0.5 < φ < 2.5) failed to auto-ignite within the test section. Model predictions were found to agree with the ethylene measurements, although improved qualification of the experimental boundary conditions is required in order to better understand the dependence of auto-ignition delay on the physical characteristics of the flow rig. The chemical kinetic model used in this study was compared with existing ‘low temperature’ measurements and correlations for methane and natural gas and was found to be in good agreement.

Ignition Delay Time and Laminar Flame Speed Calculations for Natural Gas/Hydrogen Blends at Elevated Pressures

“…The reactivity of methane has been studied extensively at gas turbine conditions, and the flame speed and ignition delay time of this fuel can be considered well known [4,5]. Additionally, several studies have been performed to determine the flame speeds [6,7] and ignition delay times [7,8,9] of different methane-based fuels that simulate natural gas. The reactivity of hydrogen has also been extensively studied [1,10].…”