Flame Imaging of Gas-Turbine Relight

Read, Robert; Rogerson, Jim; Hochgreb, Simone

doi:10.2514/1.j050105

Cited by 42 publications

(20 citation statements)

References 16 publications

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“…From locations with positive axial velocity, the kernel may get convected downstream, but if the flame grows enough in the radial direction to get inside the recirculation zone, then the flame has a good chance of growing fully. The movement of the flame upstream is key to successful ignition, consistent with previous work with nonpremixed [21] and spray [3] laboratory flames and single-sector gas turbine combustors [24,25].…”

Section: Ignition Visualisationsupporting

confidence: 83%

Simulations and experiments on the ignition probability in turbulent premixed bluff-body flames

Sitte

Bach

Kariuki

et al. 2016

Combustion Theory and Modelling

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The ignition characteristics of a premixed bluff-body burner under lean conditions were investigated experimentally and numerically with a physical model focusing on ignition probability. Visualisation of the flame with a 5 kHz OH* chemiluminescence camera confirmed that successful ignitions were those associated with the movement of the kernel upstream, consistent with previous work on non-premixed systems. Performing many separate ignition trials at the same spark position and flow conditions resulted in a quantification of the ignition probability P ign , which was found to decrease with increasing distance downstream of the bluff body and a decrease in equivalence ratio. Flows corresponding to flames close to the blow-off limit could not be ignited, although such flames were stable if reached from a richer already ignited condition. A detailed comparison with the local Karlovitz number and the mean velocity showed that regions of high P ign are associated with low Ka and negative bulk velocity (i.e. towards the bluff body), although a direct correlation was not possible. A modelling effort that takes convection and localised flame quenching into account by tracking stochastic virtual flame particles, previously validated for non-premixed and spray ignition, was used to estimate the ignition probability. The applicability of this approach to premixed flows was first evaluated by investigating the model's flame propagation mechanism in a uniform turbulence field, which showed that the model reproduces the bending behaviour of the S T -versus-u curve. Then ignition simulations of the bluff-body burner were carried out. The ignition probability map was computed and it was found that the model reproduces all main trends found in the experimental study.

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Section: Ignition Visualisationsupporting

confidence: 83%

Simulations and experiments on the ignition probability in turbulent premixed bluff-body flames

Sitte

Bach

Kariuki

et al. 2016

Combustion Theory and Modelling

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“…Although real geometries of gas turbine combustion chambers are complex and the operating conditions (pressure and temperature) restrictive, some experimental studies have already been performed in a generic test rig or engine combustor (Moesl et al, 2009;Naegeli and Dodge, 1991;Read, 2010;Xiong, 1981). Moreover, large eddy simulation (LES) of spark ignition in gas turbine combustors have also been performed recently (Boileau et al, 2008;Jones and Tyliszczak, 2010).…”

Section: Please Scroll Down For Articlementioning

confidence: 99%

“…led to the same conclusion that no systematic correlations between local flow properties and P Ign exist. Another analysis was thus proposed by coupling local conditions with flame history data from ignition through to stabilization (Ahmed et al, 2007;Mastorakos, 2009;Read et al, 2010;Subramanian et al, 2010). From an experimental point of view, high-speed flame imaging allowed us to complete the previous analysis and give some ignition scenarios.…”

Section: Laser-induced Spark Ignition Of Swirled Flames 393mentioning

confidence: 99%

Laser-Induced Spark Ignition of Premixed Confined Swirled Flames

Cordier

Vandel

Cabot

et al. 2013

Combustion Science and Technology

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Optimization of the ignition location is of crucial importance for many combustion systems and requires advanced knowledge of the ignition process for both fundamental and applied configurations. In this article, a premixed swirl burner was designed to experimentally study the impact of the spark location on successful ignition and to detail the scenario from ignition to flame stabilization. Two swirl numbers were investigated to evaluate their impact on the ignition process. Particular attention was paid to providing accurate data on cold flow velocity field statistics (obtained by stereoscopic particle image velocimetry) as well as on ignition conditions. Ignition probability maps were obtained for a constant level of deposited energy. Contrary to previous studies, no correlation between local turbulent kinetic energy and ignition probability was observed, and a deeper analysis of the temporal evolution of the flame kernel within the combustion chamber is required. Coupling fast flame visualization with the corresponding pressure signal demonstrated that the efficiency of the ignition location was not only controlled by the local flow properties, but also by the early flame kernel development, linked by its typical trajectories within the combustion chamber.

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“…The current diagnostic techniques used for studying ignition behaviour in gas turbine combustors include the use of a high-speed camera to record the ignition sequence and kernel movement path, laser Doppler anemometry to determine the gas phase velocity, particle image velocimetry or phase Doppler analyser to determine the liquid phase velocity, and planar Mie scattering or tomography scattering to determine the fuel spray distribution. Read et al (2010) studied the high altitude relight behaviour of a lean direct injection gas turbine combustor using a high-speed camera and proposed four ignition failure modes within the flame growth and establishment phases: a) rapid disintegration, b) flame exit, c) flame split, and d) lack of flame stabilization at the injector. Mosbach et al (2010) also researched the high altitude relight process of a lean combustor using a high-speed camera and found that stable ignition and flame establishment were closely related to the flow field, fuel spray distribution, and local equivalence ratio distribution.…”

Section: Introductionmentioning

confidence: 99%

Ignition Failure Modes During Ignition Kernel Propagation in Swirl Spray Flame

Mi¹,

Zhang²,

Xin³

et al. 2019

Proceedings of Global Power &Amp; Propulsion Society

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Technological advances for lowering the emissions of rich burn-quick mix-lean burn (RQL) combustors in response to increasingly stringent emissions regulations will be accompanied by more challenging operability issues, especially ignition along the flight envelope for both conventional and alternative aviation fuels. The aim of this paper is to research the ignition failure modes during ignition kernel propagation in swirl spray flames. These experiments were conducted on an optically accessible single fuel nozzle RQL model combustor featuring a fuel-air mixing device and combustor primary and dilution zones established by two rows of primary/dilution jets. The ignition tests were performed at both atmospheric and sub-atmospheric pressures, and the total pressure loss across the liner varied from 1% to 6%. A highspeed camera was utilized to capture images of the kernel and flame propagation during the ignition process. The camera frame speed rate was 6750 Hz with 1/51000 s exposure time and the image resolution of 768×768 pixels covering 80×80 mm 2 field view of the combustor considered critical for the investigation. In the successful ignition case, the initial ignition kernel generated near the igniter was transported and stabilized downstream of the swirler exit, followed by stable combustion covering the entire combustor. In the failed ignition cases, the ignition kernel underwent a series of breakups following its formation. In these failure cases, parts of the sub-kernel were extinguished while the rest moved downstream towards the combustor exit, indicating that the kernel was not transported to the primary zone flame stabilizing portion of the combustor. Three ignition failure modes were determined from the high-speed images: ignition kernel "extinction", ignition kernel "breakup", and ignition kernel "downstream movement". While flameout in gas turbine combustors is mainly caused by aerodynamic quenching and/or fuel starvation, the alternation of ignition failure modes can be correlated with the fuel-air ratio and air mass flow rate.

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Flame Imaging of Gas-Turbine Relight

Cited by 42 publications

References 16 publications

Simulations and experiments on the ignition probability in turbulent premixed bluff-body flames

Simulations and experiments on the ignition probability in turbulent premixed bluff-body flames

Laser-Induced Spark Ignition of Premixed Confined Swirled Flames

Ignition Failure Modes During Ignition Kernel Propagation in Swirl Spray Flame

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