Mitigating thermoacoustic instabilities in a Rijke tube burner using iron nanopowder additives

Abstract

This study introduces a novel passive control method for mitigating thermoacoustic instabilities by adding iron nanopowder to the flame within a Rijke tube. A comprehensive experimental setup was designed to investigate how varying nanopowder concentrations influence self-excited oscillations at different Rijke tube lengths. Results show that even small amounts of iron nanopowder can suppress certain high-frequency instability modes or induce nonlinear behavior, such as mode switching from higher to lower modes. At higher concentrations, thermoacoustic instabilities can be almost entirely eliminated. Detailed analysis reveals that iron nanopowder mitigates thermoacoustic instabilities by extending the flame length, which reduces the heat release rate gain to the system, and by enhancing particle-induced acoustic damping.