Amplitude death in coupled thermoacoustic oscillators via asymmetric open-loop forcing

We experimentally apply asymmetric open-loop forcing to a pair of thermoacoustic oscillators interacting via dissipative and time-delayed coupling, with the aim of promoting amplitude death (AD) and partial amplitude death (PAD). Two baseline states are considered: (i) in-phase synchronization at a common limit-cycle frequency and (ii) desynchronization at two incommensurate frequencies. As the forcing strengthens at non-resonant frequencies, partial forced synchronization (PFS) first emerges in the driven oscillator, then in the undriven one, and ultimately in both oscillators. Each PFS onset is governed by a competition between the natural and forced modes, including a collapse of partial mutual synchronization in the desynchronized state as PFS takes over. Forcing at frequencies far from the natural frequency yields full AD in both the synchronized and desynchronized states, and expands the PAD regime in the unforced oscillator via asynchronous quenching. A low-order model of two asymmetrically forced coupled Van der Pol oscillators accurately captures these dynamics. Our findings demonstrate that asymmetric open-loop forcing can promote AD and PAD in a coupled thermoacoustic system, suggesting a practical strategy for active control of can-annular combustors.