Effect of heat source on transient energy growth analysis of a thermoacoustic system. (1st January 2015)

• Record Type: Journal Article
• Authors: Li, X.Y.; Zhao, Dan; Li, S.H.; Ji, C.Z.
• Is Part Of: Energy conversion and management. Volume 89(2015)
• Page Start: 309
• Page End: 317
• Publication Date: 2015-01-01
• Subjects: Thermoacoustic oscillation -- Transient energy growth -- Combustion instability -- Premixed flame -- Non-normality -- Heat-to-sound conversion; Direct energy conversion -- Periodicals; Energy storage -- Periodicals; Energy transfer -- Periodicals; Énergie -- Conversion directe -- Périodiques; Direct energy conversion; Periodicals; 621.3105
• DOI: 10.1016/j.enconman.2014.09.075
• Languages: English
• ISSNs: 0196-8904

Abstract

Highlights: Transient growth analysis of a thermoacoustic system is conducted. A thermoacoustic model of a premixed flame is developed. Four key parameters are identified and studied. The flame-acoustics interaction can lead to transient energy growth. The flame is discretized into distributed monopole-like sound sources. Abstract: Transient growth of disturbances in a non-normal combustion system could trigger thermoacoustic instability. In this work, the effect of heat source on triggering thermoacoustic instability in a system with Dirichlet or Neumann boundary conditions is investigated. For this a thermoacoustic model of a premixed laminar flame is developed. It is formulated in state-space by expanding flow disturbances via Galerkin series and coupling with a flame model, thus providing a platform on which to gain insight on the system stability behaviors. Transient energy growth analysis is then performed by discretizing the flame model into distributed monopole-like sound sources. It is shown that the thermoacoustic system is non-normal and associated with transient energy growth. Parametric studies are then conducted to study the effects of (1) the flame-acoustics interaction index I, (2) the eigenmode number N, (3) the mean temperature ratio T between pre- and after-combustion regions on the system stability behavior and non-normality. It is found that the maximum transient energy growth G max is increased with increased I . Furthermore, the thermoacoustic system with more eigenmodes is found to be associated with a larger G max .