Role of Flame Dynamics on the Bifurcation Characteristics of a Ducted V-Flame

Vishnu, R.; Sujith, R. I.; Aghalayam, Preeti

doi:10.1080/00102202.2014.979287

Cited by 21 publications

(31 citation statements)

References 18 publications

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“…Here we examine the features of the full dispersion relation (10) numerically. For certainty, we consider as an example a combustor with the parameters of the test rig at IIT Madras (Vishnu et al [25]): the length L is 0.75 m, the cross-section S is 0.0016 m 2 (based on 45 mm inner diameter of the lab scale combustor setup), the temperature T is constant throughout the duct and equal to 297 K when there is no flame. Figure 2: Sketch of the experimental setup (e.g.…”

Section: Understanding the Stability Behavior Of Intrinsic Modesmentioning

confidence: 99%

“…Figure 2: Sketch of the experimental setup (e.g. Vishnu et al [25] and Mukherjee et al [26]). The glass duct, marked by thick line (blue online) shows combustor wall.…”

Section: Understanding the Stability Behavior Of Intrinsic Modesmentioning

confidence: 99%

“…However, discussing figure 9 we have to mention that there are also isolated nearly vertical segments of the neutral curve we opted not to show in the figure. These segments correspond to c i segments located between the large loop on the right and the first small loop on the left of the figure and are also due to acoustic modes coupled with intrinsic modes.Note that according to(25),(26), th i n can be either positive or negative. Of course, only positiveth i n have physical sense.…”

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confidence: 99%

“…Effect of cross-section jump on the stability domain for The plot is based on(25) and shows no cross-section jump ( 21 SS =1…”

mentioning

confidence: 99%

“…mode for certain bands of  , there is a threshold in n above which the mode becomes unstable. The threshold depends on the characteristics of the combustor and flame position, as explicitly given by expression(25). For each intrinsic mode the convoluted neutral curve separating stability and instability domains is made of segments of three types specified by the equations 0 is the discrepancy between the real part of the frequency on the neutral curve and the real part of the frequency in the limit of small n .…”

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Intrinsic flame instabilities in combustors: Analytic description of a 1-D resonator model

Mukherjee

Shrira

2017

Combustion and Flame

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The study is concerned with theoretical examination of thermo-acoustic instabilities in combustors and focuses on recently discovered 'flame intrinsic modes'. These modes differ qualitatively from the acoustic modes in a combustor. Although these flame intrinsic modes were intensely studied, primarily numerically and experimentally, the instability properties and dependence on the characteristics of the combustor remain poorly understood. Here we investigate analytically the properties of intrinsic modes within the framework of a linearized model of a quarter wave resonator with temperature and cross-section jump across the flame, and a linear n   model of heat release. The analysis of dispersion relation for the eigen-modes of the resonator shows that there are always infinite numbers of intrinsic modes present. In the limit of small interaction index n the frequencies of these modes depend neither on the properties of the resonator, nor on the position of the flame. For small n these modes are strongly damped. The intrinsic modes can become unstable only if n exceeds a certain threshold. Remarkably, on the neutral curve the intrinsic modes become completely decoupled from the environment. Their exact dispersion relation links the intrinsic mode eigen-frequency i  with the mode number i m and the time lag  :    21 ii mm        , where m =0, +/-1. The main results of the study follow from the mode decoupling on the neutral curve and include explicit analytic expressions for the exact neutral curve on the n   plane, and the growth/decay rate dependence on the parameters of the combustor in the vicinity the neutral curve. The instability domain in the parameter space was found to have a very complicated shape, with many small islands of instability, which makes it difficult, if not impossible, to map it thoroughly numerically. The analytical results have been verified by numerical examination.

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Section: Understanding the Stability Behavior Of Intrinsic Modesmentioning

confidence: 99%

“…Figure 2: Sketch of the experimental setup (e.g. Vishnu et al [25] and Mukherjee et al [26]). The glass duct, marked by thick line (blue online) shows combustor wall.…”

Section: Understanding the Stability Behavior Of Intrinsic Modesmentioning

confidence: 99%

mentioning

confidence: 99%

“…Effect of cross-section jump on the stability domain for The plot is based on(25) and shows no cross-section jump ( 21 SS =1…”

mentioning

confidence: 99%

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confidence: 99%

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