Comparison of Flame Transfer Functions Acquired by Chemiluminescence and Density Fluctuation

2016 ◽  
Author(s):  
Johannes Peterleithner ◽  
Riccardo Basso ◽  
Franz Heitmeir ◽  
Jakob Woisetschläger ◽  
Raimund Schlüßler ◽  
...  
Keyword(s):  
Equivalence Ratio ◽  
Transfer Functions ◽  
Turbulent Flame ◽  
Time Derivative ◽  
Density Fluctuations ◽  
Time Resolved ◽  
Partially Premixed Flames ◽  
Partially Premixed ◽  
Premixed Turbulent Flame ◽  
First Time

The goal of this study was to measure the Flame Transfer Function of a perfectly and a partially premixed turbulent flame by means of Laser Interferometric Vibrometry. For the first time, this technique is used to detect integral heat release fluctuations. The results were compared to classical OH*-chemiluminescence measurements. Effects of equivalence ratio waves and vortex rollup were found within those flames and were then investigated by means of time resolved planar CH*/OH*-chemiluminescence and Frequency modulated Doppler global velocimetry. This work is motivated by the difficulties chemiluminescence encounters when faced with partially premixed flames including equivalence ratio waves and flame stretching. LIV, recording the time derivative of the density fluctuations as line-of-sight data, is not affected by these flame properties.

Time and Space Series Analysis of Spectral Radiation Intensities for a Partially Premixed Turbulent Flame

2003 ◽  
Author(s):  
Yuan Zheng ◽  
Jay P. Gore
Keyword(s):  
Single Point ◽  
Turbulent Flame ◽  
Premixed Flames ◽  
Model Parameters ◽  
Time And Space ◽  
Spectral Radiation ◽  
Series Analysis ◽  
Partially Premixed Flames ◽  
Partially Premixed ◽  
Premixed Turbulent Flame

A recently developed technique called time and space series analysis was used to calculate the mean and fluctuating spectral radiation intensities leaving diametric and chord-like paths in turbulent partially premixed flames. A standard flame (Flame D) from Sandia Workshop on Turbulent Non-premixed Flames was selected to allow an evaluation of the radiation calculations at least at the single point statistics level. Measurements of spectral radiation intensities using a fast infrared array spectrometer provide an evaluation of the computations and also allow estimation of the length and time scales of scalar fluctuations, which appear as model parameters in the time and space series analysis modeling.

scholarly journals Lean partially premixed turbulent flame equivalence ratio measurements using laser-induced breakdown spectroscopy

Fuel ◽  
2019 ◽  
Vol 237 ◽  
pp. 320-334 ◽  
Author(s):  
Tawfik Badawy ◽  
Mahmoud Hamza ◽  
Mohy S. Mansour ◽  
Abdel-Hafez H. Abdel-Hafez ◽  
Hisham Imam ◽  
...  
Keyword(s):  
Equivalence Ratio ◽  
Turbulent Flame ◽  
Laser Induced Breakdown Spectroscopy ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
Partially Premixed ◽  
Premixed Turbulent Flame

Numerical Analysis of Equivalence Ratio Fluctuations in a Partially Premixed Gas Turbine Combustor Using Large Eddy Simulations

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Ping Wang ◽  
Qian Yu ◽  
Prashant Shrotriya ◽  
Mingmin Chen
Keyword(s):  
Reaction Mechanism ◽  
Equivalence Ratio ◽  
Flame Temperature ◽  
Premixed Flames ◽  
Large Eddy Simulations ◽  
Combustion Model ◽  
Inlet Channel ◽  
Large Eddy ◽  
Partially Premixed Flames ◽  
Partially Premixed

In the present work, the fluctuations of equivalence ratio in the PRECCINSTA combustor are investigated via large eddy simulations (LES). Four isothermal flow cases with different combinations of global equivalence ratios (0.7 or 0.83) and grids (1.2 or 1.8 million cells) are simulated to study the mixing process of air with methane, which is injected into the inlet channel through small holes. It is shown that the fluctuations of equivalence ratio are very large, and their ranges are [0.4, 1.3] and [0.3, 1.2] for cases 0.83 and 0.7, respectively. For simulating turbulent partially premixed flames in this burner with the well-known dynamically thickened flame (DTF) combustion model, a suitable multistep reaction mechanism should be chosen aforehand. To do that, laminar premixed flames of 15 different equivalence ratios are calculated using three different methane/air reaction mechanisms: 2S_CH4_BFER, 2sCM2 reduced mechanisms and GRI-Mech 3.0 detailed reaction mechanism. The variations of flame temperature, flame speed and thickness of the laminar flames with the equivalence ratios are compared in detail. It is demonstrated that the applicative equivalence ratio range for the 2S_CH4_BFER mechanism is [0.5, 1.3], which is larger than that of the 2sCM2 mechanism [0.5, 1.2]. Therefore, it is recommended to use the 2S_CH4_BFER scheme to simulate the partially premixed flames in the PRECCINSTA combustion chamber.

scholarly journals Evaluation of partially premixed turbulent flame stability from mixture fraction statistics in a slot burner

2018 ◽  
pp. 1-17 ◽  
Author(s):  
Stephan Kruse ◽  
Mohy S. Mansour ◽  
Ayman M. Elbaz ◽  
Emilien Varea ◽  
Gerd Grünefeld ◽  
...  
Keyword(s):  
Mixture Fraction ◽  
Turbulent Flame ◽  
Flame Stability ◽  
Partially Premixed ◽  
Premixed Turbulent Flame

Analysis of Measured Flame Transfer Functions With Locally Resolved Density Fluctuation and OH-Chemiluminescence Data

2015 ◽  
Author(s):  
Johannes Peterleithner ◽  
Nicolai V. Stadlmair ◽  
Jakob Woisetschläger ◽  
Thomas Sattelmayer
Keyword(s):  
Heat Release ◽  
Density Fluctuation ◽  
Equivalence Ratio ◽  
Transfer Functions ◽  
Rotational Symmetry ◽  
Periodic Oscillation ◽  
Density Fluctuations ◽  
Combustion Noise ◽  
Line Of Sight ◽  
Laser Vibrometer

The goal of the study presented in this paper is to analyze flame transfer functions with a new approach based on the combination of-line-of sight OH*-chemiluminescence and density fluctuation data. The OH*-chemiluminescence is acquired with a photomultiplier and an intensified camera, the density fluctuations are measured with a Laser vibrometer on a two axis traverse. In flames with forcing the acoustic fluctuations can be extracted from the data by discrimination of all contributions from combustion noise, because it is not correlated with the excitation device. Assuming rotational symmetry of the fluctuations originating from excitation, planar phase-resolved and pseudo-local OH*-chemiluminescence and density fluctuation data is obtained from the measured line-of-sight integrated signals. In the study this technique is applied to a swirl burner configuration with FTFs from known multi-microphone measurements (MMM). In the first step, the externally premixed mode without equivalence ratio fluctuations is studied and in the second step the fuel is injected in the swirler in order to generate equivalence ratio waves. At selected frequencies the planar fields of the OH*-chemiluminescence and density fluctuations are compared to the FTFs in order to improve the understanding regarding the specific amplitude and phase values. In addition to heat release the vibrometer data reveals the periodic oscillation of the conical annular jet of the cold reactants in the combustor filled with hot products. On the global scale the amplitudes and phases of heat release expected from the MMM are satisfactorily reproduced by both methods for the premixed cases, whereas OH*-chemiluminescence data cannot be used as indicator for heat release if equivalence ratio fluctuations are present, because the amplitude of the FTF is significantly over-predicted due to the sensitivity of OH* on the local fuel-air mixture.

Analysis of Measured Flame Transfer Functions With Locally Resolved Density Fluctuation and OH-Chemiluminescence Data

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Johannes Peterleithner ◽  
Nicolai V. Stadlmair ◽  
Jakob Woisetschläger ◽  
Thomas Sattelmayer
Keyword(s):  
Heat Release ◽  
Density Fluctuation ◽  
Equivalence Ratio ◽  
Transfer Functions ◽  
Periodic Oscillation ◽  
Global Scale ◽  
Laser Vibrometry ◽  
Annular Jet ◽  
Partially Premixed ◽  
Hot Products

The goal of this study is to analyze flame transfer functions (FTFs) locally by quantifying the heat release rate with OH*-chemiluminescence and density fluctuation measurements using laser vibrometry. In this study, both techniques are applied to a swirl burner configuration with known FTFs acquired by multimicrophone-method (MMM) measurements for perfectly premixed and partially premixed cases. The planar fields of the quantities are compared to the FTFs in order to improve the understanding regarding the specific amplitude and phase values. On the global scale values of heat release expected from the MMM are satisfactorily reproduced by both methods for the premixed cases, whereas OH*-chemiluminescence data cannot be used as indicator for heat release in the partially premixed case, where equivalence ratio fluctuations are present. Vibrometry is not affected by fluctuations of equivalence ratio but additionally reveals the periodic oscillation of the conical annular jet of the cold reactants in the combustor filled with hot products.

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