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JournalISSN: 1756-8277

International Journal of Spray and Combustion Dynamics 

SAGE Publishing
About: International Journal of Spray and Combustion Dynamics is an academic journal published by SAGE Publishing. The journal publishes majorly in the area(s): Combustion & Combustor. It has an ISSN identifier of 1756-8277. It is also open access. Over the lifetime, 248 publications have been published receiving 2934 citations. The journal is also known as: Spray and combustion dynamics & IJSCD.


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Journal ArticleDOI
TL;DR: In this article, a series of determinism tests were used to show that these aperiodic fluctuations are in fact chaotic of moderately high dimensions (d0 ≈ 8-10) and these chaotic fluctuations then transition to high amplitude combustion instability when the operating conditions are varied towards leaner equivalence ratios.
Abstract: Combustion noise has been traditionally thought of as stochastic fluctuations present in the background of the dynamics in combustors amongst the flow, heat release and the chamber acoustics. Through a series of determinism tests, we show that these aperiodic fluctuations are in fact chaotic of moderately high dimensions (d0 ≈ 8-10). These chaotic fluctuations then transition to high amplitude combustion instability when the operating conditions are varied towards leaner equivalence ratios. Precursors to such a transition from chaos to dynamics dominated by periodic oscillations are of interest to designers and operators of combustors in estimating the boundaries of operability. We introduce a test for chaos, known as 0-1 test for chaos in the literature, as a measure of the proximity of the combustor to an impending instability. The measure is robust and shows a smooth transition for variation in flow conditions towards instability enabling thresholds to be set for operational boundaries.

118 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of the mean flow on thermoacoustic instabilities were investigated in a simple quasi-1D configuration of a 1D premixed flame in a duct connected to a nozzle.
Abstract: This paper presents an analytical/numerical study of the effects of the mean flow on thermoacoustic instabilities. Simple quasi-1D configurations such as a 1D premixed flame in a duct connected to a nozzle are considered in order to investigate to what extent the frequency of oscillation and growth rate are modified when the Mach number is not zero. It is demonstrated that the zero Mach number assumption for the mean flow can lead to significant errors, especially when the mean flow is not isentropic, a condition which is always met in combustion applications. The analysis confirms that terms involving the mean velocity may contribute to the disturbance energy equation as much as the flame forcing ('Rayleigh') term. Besides, the net effect of the non zero Mach number terms on the stability of the modes strongly depends on both the boundary conditions and the flame response. For moderate Mach number values of order 0.05, the errors made by assuming that the mean flow is at rest are large enough to change the stability of the frequencies of interest in an academic combustor.

105 citations

Journal ArticleDOI
TL;DR: In this article, five stages of flow physics have been identified as being important, these being (a) generation of entropy waves by unsteady heat release rate; (b) advection of entropy wave through the combustor; (c) acceleration of entropy noise through either a nozzle or blade row, to generate entropy noise; (d) passage of entropy noises through a succession of turbine blade rows to appear at the turbine exit; and (e) re...
Abstract: Combustion noise comprises two components: direct combustion noise and indirect combustion noise. The latter is the lesser studied, with entropy noise believed to be its main component. Entropy noise is generated via a sequence involving diverse flow physics. It has enjoyed a resurgence of interest over recent years, because of its increasing importance to aero-engine exhaust noise and a recognition that it can affect gas turbine combustion instabilities. Entropy noise occurs when unsteady heat release rate generates temperature fluctuations (entropy waves), and these subsequently undergo acceleration. Five stages of flow physics have been identified as being important, these being (a) generation of entropy waves by unsteady heat release rate; (b) advection of entropy waves through the combustor; (c) acceleration of entropy waves through either a nozzle or blade row, to generate entropy noise; (d) passage of entropy noise through a succession of turbine blade rows to appear at the turbine exit; and (e) re...

103 citations

Journal ArticleDOI
TL;DR: In this article, a bifurcation analysis of the dynamical behavior of a horizontal Rijke tube model is performed, including the amplitude of the unstable limit cycles, and the linear and nonlinear stability boundaries are obtained for the simultaneous variation of two parameters of the system.
Abstract: A bifurcation analysis of the dynamical behavior of a horizontal Rijke tube model is performed in this paper. The method of numerical continuation is used to obtain the bifurcation plots, including the amplitude of the unstable limit cycles. Bifurcation plots for the variation of nondimensional heater power, damping coefficient and the heater location are obtained for different values of time lag in the system. Subcritical bifurcation was observed for variation of parameters and regions of global stability, global instability and bistability are characterized. Linear and nonlinear stability boundaries are obtained for the simultaneous variation of two parameters of the system. The validity of the small time lag assumption in the calculation of linear stability boundary has been shown to fail at typical values of time lag of system. Accurate calculation of the linear stability boundary in systems with explicit time delay models, must therefore, not assume a small time lag assumption. Interesting dynamical ...

97 citations

Journal ArticleDOI
TL;DR: In this paper, a multiple-input, single-output (MISO) model structure for the flame is developed, where the integration with low-order or finite-element based models for stability analysis is straightforward.
Abstract: For the analysis of thermoacoustic instabilities it is most important to determine the dynamic flame response to acoustic disturbances. Premixed flames are often modelled as single-input single-output system, where the “output” (the overall rate of heat release) responds to a single “input” variable (often the velocity at the exit of the burner nozzle). However, for practical premixed flames, where perturbations of pressure or velocity at the fuel injector will modulate the fuel equivalence ratio, the heat release rate will respond to fluctuations of equivalence ratio as well as nozzle mass flow rate. In this case, a multiple-input, single-output (MISO) model structure for the flame is appropriate. Such a model structure is developed in the present paper. Staged fuel injection as well as fuel line impedances can be taken into account, the integration with low-order or finite-element based models for stability analysis is straightforward. In order to determine unit impulse and frequency response functions ...

59 citations

Performance
Metrics
No. of papers from the Journal in previous years
YearPapers
202314
202223
20219
20209
20199
201823