Metamorphosis of transition to periodic oscillations in a turbulent reactive flow system

TL;DR

This study experimentally investigates how turbulent reactive flow systems transition to periodic oscillations, revealing five distinct bifurcation types influenced by fuel ratio and secondary parameters, aiding better control of such dynamics.

Contribution

It identifies and characterizes five different transition types to oscillations in turbulent reactive flows, highlighting the influence of secondary parameters on bifurcation nature.

Findings

Five qualitatively distinct transition types identified

Transitions include both continuous and discontinuous bifurcations

Insights into controlling oscillatory behavior in engineering systems

Abstract

The emergence of periodic oscillations is observed in various complex systems in nature and engineering. Thermoacoustic oscillations in systems comprising turbulent reactive flow exemplify such complexity in the engineering context, where the emergence of oscillatory dynamics is often undesirable. In this work, we experimentally study the transition to periodic oscillations within a turbulent flow reactive system, with varying fuel-to-air ratio, represented by equivalence ratio as a bifurcation parameter. Further, we explore the change in the nature of the transition by varying a secondary parameter. In our system, we vary the thermal power input and the location of the flame stabilizer position individually as a secondary parameter. Our findings reveal five qualitatively distinct types of transitions to periodic oscillations. Two types of these transitions exhibit a continuous nature. Another two types of transitions involve multiple shifts in the dynamical states consisting of both continuous and discontinuous bifurcations. The last type of transition is characterized by an abrupt bifurcation to high-amplitude periodic oscillations. Understanding this metamorphosis of the transition - from continuous to discontinuous nature - is critical for advancing our comprehension of the dynamic behavior in turbulent reactive flow systems. The insights gained from this study have the potential to inform the design and control of similar engineering systems where managing oscillatory behavior is crucial.