The turbulent lifted Dutch natural gas jet diffusion flame in cold co-flowing air is widely used in gas turbine operation and subject of the current investigation. In striving to clean and sustainable combustion, adding hydrogen to the Dutch natural gas (DNG) fuel and CO2 in the coflow is promising. Objective of this investigation is to study the effect of hydrogen fuel-addition and CO2 coflow-dilution on the stability of a turbulent lifted DNG jet diffusion flame in cold co-flowing air. OH* chemiluminescence and particle image velocimetry (PIV) are applied simultaneously at a low sampling frequency of 50 Hz to determine time-averaged statistics of the lift-off height and stabilization point location of the flame. PIV measurements at a sampling frequency of 2.5 kHz are performed to determine the transient behaviour of the stabilization point, the flow conditions at the stabilization point and the burning velocity. Hydrogen fuel-addition leads to increased flame stability. With more hydrogen in the fuel, the lift-off height reduces and the stabilization point location shifts upstream and radially inward. The burning velocity at the stabilization point increases with increasing hydrogen fuel-concentration. A significant difference is observed in the burning velocity conditioned on upstream or downstream stabilization point motion. Hydrogen enables the flame to stabilize in a region of the flow that is characterized by high gas velocity and high vorticity. CO2 dilution of the coflow leads to decreased flame stability. With increasing CO2 coflow-dilution, the lift-off height increases and the stabilization point position shifts downstream and radially outward. The burning velocity at the stabilization point increases with increasing CO2 coflow-dilution and the flame stabilizes in a flow region with significant lower vorticity.
Additionally, this report provides useful statistics of the investigated quantities and presents a description for the transient behaviour of the stabilization point.