Session: 04-44 Combustion dynamics - modeling II
Paper Number: 127399
127399 - Instability Amplitude Suppression in a Double Orifice Flow Through External Periodic Forcing
Various afterburners, ramjets and combustors exhibits vortex shedding lock-in with acoustic mode of the duct. In present study, we experimentally analyse the effect of external forcing on flow through a square duct containing two circular orifices. As the mean flow is increased, the system transitions from a noisy state to periodic oscillations (lock-in) through quasiperiodic regime. Periodic forcing of the system close to its instability frequency leads to amplitude suppression via synchronous quenching and 1:1 lock-in. The phase lock-in happens via phase drifting and phase slipping. We also observe asynchronous quenching on forcing the system far from the instability frequency. However, the phase lock-in asynchronous quenching happens via phase drifting and phase trapping.These approaches serve as effective active control strategies for instability control. Synchronization maps are presented and the dynamics of transition is explored using return maps. Finally, we present reduced order models of these phenomena using an oscillator model, which clearly capture transition from various lock-in regimes which includes saddle node bifurcation near natural frequency and torous death far from the natural frequency. Apart from that model and an alternative approach is used that transforms the continuous domain into a discrete map and syncronization map are plotted. Both models are compared with experimental results.
Presenting Author: Vineeth Nair Indian Institute of Technology Bombay
Presenting Author Biography: Prof Vineeth Nair is Associate Professor at Department of aerospace at Indian Institute of technology, Bombay from India.
Authors:
Ashutosh Singh Indian Institute of Technology BombayIsha Mukherjee Indian Institute of Technology Bombay
Vineeth Nair Indian Institute of Technology Bombay
Instability Amplitude Suppression in a Double Orifice Flow Through External Periodic Forcing
Paper Type
Technical Paper Publication