Thermoacoustic Instability in a Rijke Tube with a Distributed Heat Source

Abstract

A Rijke tube with a distributed heat source is investigated. Driven by the widely existing thermoacoustic instability in lean premixed gas turbine combustors, this work aims to explore the physicochemical underpinning and assist in the elucidation and analysis of this problem. The heat release model consists of a row of distributed heat sources with individual heat release rates. The integrated heat release rate is then coupled with the acoustic perturbation for thermoacoustic analysis. A continuation approach is employed to conduct the bifurcation analysis and capture the nonlinear behaviour inherent in the system. Unlike the conventional approach by the Galerkin method, the acoustic equations are originally discretized using the Method of Lines (MOL) to build up a dynamic system. The model is first validated and shown to yield good predictions with available experimental data. Influences of multiple heat sources, time delay, and heat release distribution are then studied to reveal the extensive nonlinear characteristics involved in the case of a distributed heat source. It is found that distributed heat source plays an important role in determining the stability of a thermoacoustic system.

Bifurcation to Limit Cycle Oscillations in Laminar Thermoacoustic Systems

“…An important advantage of the horizontal Rijke tube system is that it provides us independent controls over various system parameters, i.e., the heater power and mass flow rate of air, which was not possible in Rijke's original system with a vertical duct. Many researchers have investigated the bifurcation characteristics of a horizontal Rijke tube through experiments [29,34,60,68] and numerical simulations [47,66,94,104] for the variation of different control parameters. These parameters include the heater power, mass flow rate of air, location of the heater in the duct, noise intensity, etc.…”

“…Many numerical [2,21,25,38,39,43,47,48,59,66,68,71,76,94,95,104, 105] and experimental [3,11,16,29,33,34,44,50,52,62,67,68,72,73,77,80] studies have been performed over the years to investigate the bifurcation characteristics of thermoacoustic systems. The nonlinear behavior of thermoacoustic systems can be examined using two different methodologies, which include the describing function approach and the dynamical systems approach.…”

A Brief Review of Acoustic Excitation Toward Jet Flame Characteristics

“…Study on combustion instability are important due to under certain circumstances, it can become extremely detrimental that will eventually affect the combustion system process [1][2][3][4][5]. It exists in a wide range of applications such as the rocket propulsion engines, industrial burner, industrial processing, ramjets, afterburners and gas turbine [6][7][8][9][10].…”