Computational analysis on the stability and characteristics of partially premixed butane air open flames in tubular burner

Partially premixed combustion is one of the developing areas of combustion research that has the advantages of both premixed and diffusion mode of combustion. The present work involves a computational study on the stability and characteristics of partially premixed butane-air flames. The effect of operating parameters like fuel-air ratio, primary aeration, and the presence of co-flow and co-swirl on the stability and flame characteristics has been studied. The simulation results show that the height of the flame decreases with an increase in primary aeration and also in the presence of a co-swirl stream. It has also been found that the stability of flames increases with co-swirl air but deteriorates with the presence of the co-flow air. The flame temperature increases with primary aeration and it has been observed that the peak flame temperature shifts away from the burner mouth for lower primary aeration. It has been observed that the flame stability improves with co-swirl air which is attributed to the recirculation zone created due to the swirl motion which acts as a heat source. The poor stability in the presence of co-flow air is attributed to flame stretching and aerodynamic quenching of the stretched flame lets. The lift off velocity and the stable operating range increases with equivalence ratio and also with co-swirl air.

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Identification of Flame Regimes in Partially Premixed Combustion from a Quasi-DNS Dataset

Flow Turbulence and Combustion ◽

10.1007/s10494-020-00228-9 ◽

2020 ◽

Author(s):

Thorsten Zirwes ◽

Feichi Zhang ◽

Peter Habisreuther ◽

Maximilian Hansinger ◽

Henning Bockhorn ◽

...

Keyword(s):

Turbulent Flame ◽

Detailed Chemistry ◽

Partially Premixed Combustion ◽

Processing Step ◽

Different Types ◽

Partially Premixed ◽

Definition Of ◽

And Diffusion ◽

Combustion Regimes ◽

Term Analysis

Abstract Identifying combustion regimes in terms of premixed and non-premixed characteristics is an important task for understanding combustion phenomena and the structure of flames. A quasi-DNS database of the compositionally inhomogeneous partially premixed Sydney/Sandia flame in configuration FJ-5GP-Lr75-57 is used to directly compare different types of flame regime markers from literature. In the simulation of the flame, detailed chemistry and diffusion models are utilized and no turbulence and combustion models are used as the flame front and flow are fully resolved near the nozzle. This allows evaluating the regime markers as a post-processing step without modeling assumptions and directly comparing regime markers based on gradient alignment, drift term analysis and gradient free regime identification. The goal is not to find the correct regime marker, which might be impossible due to the different set of assumptions of every marker and the generally vague definition of the partially premixed regime itself, but to compare their behavior when applied to a resolved turbulent flame with partially premixed characteristics.

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A Hybrid Flamelet Generated Manifold Model for Modeling Partially Premixed Turbulent Combustion Flames

Volume 4B: Combustion, Fuels and Emissions ◽

10.1115/gt2017-65030 ◽

2017 ◽

Cited By ~ 2

Author(s):

Rakesh Yadav ◽

Ashoke De ◽

Sandeep Jain

Keyword(s):

Hybrid Model ◽

Laminar Flame ◽

Mixture Fraction ◽

Turbulent Flame ◽

Hybrid Approach ◽

Smooth Transition ◽

Flamelet Generated Manifold ◽

Partially Premixed ◽

Lift Off ◽

And Diffusion

In this work, a hybrid Flamelet Generated Manifold (FGM) method has been implemented in which both premixed and diffusion based laminar flame manifolds are generated independently and used within one solution framework to capture the multiple combustion regimes inside a combustor. The two manifolds are generated by solving the conservation of species and energy in a transformed space of mixture fraction and progress variable. The mixture averaged properties in a combustor are then calculated using a scalar weighted contribution of premixed and diffusion manifolds. This scalar represents the extent of premixing inside the combustor and its normalized value is obtained from a scalar product of the mean gradients of fuel and oxidizer mass fractions. A volume-weighted smoothing is performed on this normalized scalar to ensure smooth transition between the premixed to diffusion regimes and vice-versa, from one location to another location inside the combustor. This hybrid or multi-regime FGM approach is validated for two turbulent CH4-air partially premixed flames. The first flame chosen in the current work is a lifted turbulent flame, while the second flame is pilot-stabilized flame. First, the computations are performed for premixed- and diffusion-based laminar manifolds and then the results with hybrid models are presented. The results of the hybrid approach are compared for predicting the lift-off height, which is driven by the balance of turbulence and kinetics at any location. It is observed that the hybrid model leads to an improvement in the prediction of the lift-off height prediction. The new hybrid model is a generic representation of the FGM modeling, which enables its use without any a priori need to focus on a specific type of manifold creation for any combustor.

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Mapping the stability of free-jet Biogas flames under partially premixed combustion

Energy ◽

10.1016/j.energy.2020.119749 ◽

2021 ◽

pp. 119749

Author(s):

Muhammed S. Abdallah ◽

Mohy S. Mansour ◽

Nageh K. Allam

Keyword(s):

Premixed Combustion ◽

Free Jet ◽

Partially Premixed Combustion ◽

Partially Premixed ◽

The Stability

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Effects of Flame Temperature on PAHs and Soot Evolution in Partially Premixed and Diffusion Flames of a Diesel Surrogate

Energy & Fuels ◽

10.1021/acs.energyfuels.9b02315 ◽

2019 ◽

Vol 33 (11) ◽

pp. 11821-11829 ◽

Cited By ~ 7

Author(s):

Haifeng Liu ◽

Yanqing Cui ◽

Beiling Chen ◽

Dimitrios C. Kyritsis ◽

Qinglong Tang ◽

...

Keyword(s):

Diffusion Flames ◽

Flame Temperature ◽

Partially Premixed ◽

And Diffusion

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Comparison between Frequency Response of Pulsating Partially Premixed and Diffusion Flame

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.c4545.119420 ◽

2020 ◽

Vol 9 (4) ◽

pp. 178-185

Keyword(s):

Frequency Response ◽

Strouhal Number ◽

Diffusion Flame ◽

Flame Temperature ◽

Dominant Frequency ◽

Ball Valve ◽

Variable Speed ◽

Partially Premixed ◽

Variable Speed Motor ◽

And Diffusion

The objective of the current research is investigation of the pulsating flow effect on the size of partially premixed and diffusion flame, experimentally. The pulsation provided through a rotary ball valve in accordance with a variable speed motor arrangement increased the flame temperature and thus more heat is released. The used S-type thermocouple can measure the flame temperature at strouhal number [St] is 0 and 0.005 for the flow, the flame temperature has been measured at five planes as each plane has five radii. Fast Fourier Transform (FFT) has been used to determine the dominant frequency response of the pulsating flame temperatures. Increasing strouhal number of the mixture (LPG fuel and air) flow increases the turbulence intensity and thus the dominant frequency response of the pulsating flame increases. The dominant frequency at St=0 is larger than the dominant frequency at St= 0.005 for all the planes of the combustion chamber. Increasing strouhal number reduces the size of the pulsating partially premixed and diffusion flame by a maximum of 40 and 35 %, respectively. The pulsation process will optimize design of the burners.

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