Stabilization of air coflowed ammonia jet flame at elevated ambient temperatures

Abstract

Ammonia is a promising carbon-free fuel, while, understanding of ammonia jet flame is still in lack. In this work, a novel facility was applied and air coflowed ammonia jet flames were achieved in an elevated ambient temperature range, 723–923K. Stabilization regimes and limits were investigated. Stable lifted flame with a classical triple structure was observed, and critical aerodynamic parameters were measured at three specific regimes, liftoff, reattachment and blowoff. Attached flame can only be retained under laminar conditions with flow Reynolds number <150. A linear correlation between velocities of fuel jet and coflow under critical conditions was uncovered, which is different from the literature research on methane flames. Effects of partially premixing and N2 dilution were considered. Partially premixing was found harmful to stabilization at 823K, while this influence becomes unclear at 923K. Differently, a linearly adverse effect was observed under both N2-diluted jet and coflow conditions at different temperatures.