Intermittency, Secondary Bifurcation and Mixed-Mode Oscillations in a Swirl-Stabilized Annular Combustor: Experiments and Modeling
Abstract
We experimentally study thermoacoustic transitions in an annular combustor consisting of sixteen premixed, swirl-stabilized turbulent flames. We show the changes in the characteristics of bifurcations leading to the state of longitudinal thermoacoustic instability (TAI) when equivalence ratio and bulk velocity are systematically varied. Depending upon the bulk velocity, we observe different states of combustor operation when the equivalence ratio is varied. These states include combustion noise, intermittency, low-amplitude TAI, mixed-mode oscillations (MMO), and high-amplitude TAI. We closely examine the special case of MMO that is encountered during the transition from low-amplitude TAI to high-amplitude TAI. We also discuss the global and local flame dynamics observed during the state of MMO. We find that during epochs of low-amplitude oscillations of MMO, all the flames are partially synchronized, while during epochs of high-amplitude oscillations, all the flames are perfectly synchronized. Finally, we replicate the criticalities of bifurcation of the annular combustor in a phenomenological model containing sixth-order nonlinearities.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 29, 2021
- Source ID
- 10.1115/1.4049407
Entities
People
- Amitesh Roy
- Asalatha Nair
- R I Sujith
- Reeja K. V.
- Samarjeet Singh
- Swetaprovo Chaudhuri
Organizations
- Indian Institute of Technology Madras
- Office of Naval Research Global
- University of Toronto