Attached and lifted flame stabilization in a linear array of swirl injectors

2020 ◽  
Author(s):  
S.E. Jella ◽  
W.Y. Kwong ◽  
A.M. Steinberg ◽  
J-W Park ◽  
T. Lu ◽  
...  
Keyword(s):  
Linear Array ◽  
Flame Stabilization ◽  
Lifted Flame ◽  
Swirl Injectors

scholarly journals Effect of H2O dilution on lifted flame stabilization

2019 ◽  
Vol 2019 (0) ◽  
pp. 0078
Author(s):  
Defne Kiran ◽  
Kosuke Osawa ◽  
Mohamed Shamma ◽  
Yuki Minamoto ◽  
Masayasu Shimura ◽  
...  
Keyword(s):  
Flame Stabilization ◽  
Lifted Flame

Study on lifted flame stabilization under different background pressures

2021 ◽  
pp. 1-19
Author(s):  
Qiushi Qin ◽  
Zhijun Wu ◽  
Alessandro Ferrari
Keyword(s):  
High Speed ◽  
Imaging System ◽  
Experimental Tests ◽  
Combustion Products ◽  
Jet Flow ◽  
Flame Stabilization ◽  
Lifted Flame ◽  
Jet Velocity ◽  
Lift Off ◽  
Pdf Model

Abstract A numerical experimental investigation is presented for a steady methane lifted-flame and a non-reaction jet flow in a co-flow of hot combustion products from lean premixed air/hydrogen combustion. A pressurized vitiated co-flow burner has been employed to study the methane lifted flame and non-reaction jet flow under different background pressures. The lift-off height has been measured with a high-speed camera, and the central jet flow velocity has been measured by means of a Schlieren imaging system. The experimental results show that the lift-off height decreases for an increment in the background pressure and in the co-flow temperature. As far as the experimental tests on the non-reaction jet flow is concerned, the jet velocity becomes extinct faster as the background pressure rises. The evolution of the jet velocity has been proved to be another important factor that affects the lift-off height under different background pressures, in addition to the fuel autoignition delay. The simulation data led with a RANS/PDF model show that an increment in the background pressure makes the temperatures increase and induces a brighter yellow part of lifted flame, which leads to more soot production. This proves that the flame is not completely premixed. On the other hand, the Schlieren images of a non-reaction jet flow highlight that the flame is partially premixed, since the edge of the jet is not well defined, as the jet penetration increases with time.

scholarly journals Technical Applicability of Low-Swirl Fuel Nozzle for a Liquid-Fueled Industrial Gas Turbine Combustor

2012 ◽  
Author(s):  
Masamichi Koyama ◽  
Shigeru Tachibana
Keyword(s):  
Gas Turbine ◽  
Flow Characteristics ◽  
Axial Direction ◽  
Flame Stabilization ◽  
Axial Position ◽  
Axial Distance ◽  
Gas Turbine Combustor ◽  
Lifted Flame ◽  
Fuel Nozzle ◽  
Industrial Gas Turbine

This paper explores the technical applicability of a low-swirl fuel nozzle designed for use with a liquid-fueled industrial gas turbine combustor. Particle image velocimetry was applied to measure nozzle flow fields with an open methane-air premixed flame configuration. Herein we discuss the effects of the chamfer dimensions of the nozzle tip on flow characteristics. The profiles indicate parallel shifts in axial direction that depend on chamfer dimensions. When velocity is normalized by bulk velocity and plotted against axial distance from the virtual origins, the profiles are consistent. This means that chamfer dimensions primarily affect the axial position of the flame, while keeping other flow characteristics, such as global stretch rate, unchanged. Then, the atmospheric combustion test was conducted with kerosene in a single-can combustor. Lifted flame stabilization was confirmed by observing the flames through a window. Lastly, an engine test was performed to assess the technical applicability of the fuel nozzle under real engine conditions. The engine testbed was a 290 kW simple-cycle liquid-fueled gas turbine engine. The configurations of the fuel nozzle were consistent with the ones used in the PIV and the atmospheric combustion test. Wall temperatures close to the fuel nozzle exit were within the acceptable range, even without the cooling air required with conventional combustors. This is an advantage of the lifted flame stabilization technique. NOx emissions were below maximum levels set under current Japanese regulations (<84 ppm@15% O2). In sum, the proposed fuel nozzle design shows promise for use with liquid-fueled industrial gas turbine engines.

The Role of Flame–flow Interactions on Lean Premixed Lifted Flame Stabilization in a Low Swirl Flow

2021 ◽  
pp. 1-25
Author(s):  
Mohammad Shahsavari ◽  
Mohammad Farshchi ◽  
Mohammad Hossein Arabnejad ◽  
Bing Wang
Keyword(s):  
Swirl Flow ◽  
Flame Stabilization ◽  
Lifted Flame ◽  
Lean Premixed ◽  
Flow Interactions

RANS and LES Modeling of a Linear-Array Swirl Burner Using a Flamelet-Progress Variable Approach

2018 ◽  
Author(s):  
Sandeep Jella ◽  
Gilles Bourque ◽  
Jeffrey Bergthorson ◽  
Wing Yin Kwong ◽  
Adam Steinberg
Keyword(s):  
Velocity Field ◽  
Linear Array ◽  
Flame Stabilization ◽  
Stereoscopic Particle Image Velocimetry ◽  
Transitional Flow ◽  
Scalar Dissipation ◽  
Flame Surface ◽  
Recirculation Bubble ◽  
Progress Variable ◽  
Variable Approach

Multiple, interacting flames in DLE systems can increase flame surface area and promote mixing of hot-products into the reactants — leading to an efficient usage of combustion volume and improved injector performance. An optically-accessible, confined, linear array of five swirl nozzles was recently built [1] to investigate flame dynamics and validate computational strategies. The present work focuses on modeling a dataset representative of lean gas turbine conditions, using a flamelet approach. A preheated (500K), premixed fuel-air mixture (ϕ = 0.55, Tflame = 1732K) at atmospheric pressure was injected through the swirlers at 40 m/s into a rectangular chamber. High-speed laser measurements of the flow (3 component velocity field from 10 kHz stereoscopic particle image velocimetry (S-PIV)) and flame (planar laser induced fluorescence of the hydroxyl radical (OH-PLIF)) were used for model validation. The objectives of this work: (1) Evaluate a flamelet-progress variable method based on flamelet-generated manifolds (FGM) and examine its sensitivity to models for micro (scalar dissipation) and large scale mixing (anisotropic RANS vs LES) and (2) Obtain insight into the velocity field and flame stabilization in an interacting system. Computations indicate that high-swirl nozzles produce bluff-body flames anchored to shear-layer vortices due to an arrested flow expansion. The anisotropic RANS turbulence model under-predicts the recirculation zone strength but predicts flow development and Reynolds stress profiles fairly well. While LES is more accurate overall, both models over-predict flow fluctuations in the transitional flow at the end of the recirculation bubble where flow becomes axially positive. The flamelet approach predicts the flame-shape and length correctly but over-predicts the reaction rate in-between swirlers. The effect of including a reactive SDR model is to significantly increase flame-flow interaction (higher scalar variance) but does not appear to influence the overall shape or location of the flame.

Observations on the leading edge in lifted flame stabilization

1999 ◽  
Vol 119 (1-2) ◽  
pp. 199-202 ◽  
Author(s):  
K.A. Watson ◽  
K.M. Lyons ◽  
J.M. Donbar ◽  
C.D. Carter
Keyword(s):  
Leading Edge ◽  
Flame Stabilization ◽  
Lifted Flame

Experimental and Numerical Analysis of Gas Premix Turbulent Flames Stabilized in a Swirl Burner With Central Bluff Body

2020 ◽  
Author(s):  
Fernando Biagioli ◽  
Alessandro Innocenti ◽  
Steffen Terhaar ◽  
Teresa Marchione
Keyword(s):  
Numerical Analysis ◽  
Burning Rate ◽  
Axial Velocity ◽  
Bluff Body ◽  
Reverse Flow ◽  
Flame Stabilization ◽  
Turbulent Flames ◽  
Swirl Burner ◽  
Lifted Flame ◽  
Flame Behaviour

Abstract Lean premixed gas turbulent flames stabilized in the flow generated by an industrial swirl burner with a central bluff body are experimentally found to behave bi-stable. This bi-stable behaviour, which can be triggered via a small change in some of the controlling parameters, for example the bulk equivalence ratio, consists in a rather sudden transition of the flame from completely lifted to well attached to the bluff body. This has impact on combustion dynamics, emissions and pressure losses. While several experimental investigations exist on this topic, numerical analysis is limited. The present work is therefore also of numerical nature, with a two-fold scope: a) simulation and validation with experiments of the bi-stable flame behaviour via Computational Fluid Dynamics (CFD) in the form of Large Eddy Simulation (LES) and b) analysis of CFD results to shed light on the flame stabilization properties. LES results, in case of the lifted flame, show that the vortex core is sharply precessing at a given frequency. Phase averaging these results at the frequency of precession clearly indicates a counter-intuitive and unexpected presence of reverse flow going all the way through the flame apex and the bluff body tip. The counter-intuitive presence of a lifted flame is explained here in terms of the phase averaged data which show that the flame apex is not placed at the centre of the spinning reverse flow region. It is instead slightly shifted radially outward where the axial velocity recovers to low positive values of the order of the turbulent burning rate. A simple one-dimensional flame stabilization model is applied to explain this peculiar flame behaviour. This model provides first an estimation of the flame radius of curvature in terms of axial velocity and turbulence quantities. This radius is therefore used to determine the total flux of reactants into the flame, given by an axial convection and a radial diffusion contributions. Subsequently the possibility of the flame positioned at the centre of the vortex is excluded based on the balance between this flux and the turbulent burning rate. A clear explanation of the mechanism leading to the sudden flame jump has instead not been identified and only some hypotheses are provided.

Three-dimensional direct numerical simulation of a turbulent lifted hydrogen jet flame in heated coflow: flame stabilization and structure

2009 ◽  
Vol 640 ◽  
pp. 453-481 ◽  
Author(s):  
C. S. YOO ◽  
R. SANKARAN ◽  
J. H. CHEN
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Heat Release ◽  
Three Dimensional ◽  
Flame Stabilization ◽  
Flux Analysis ◽  
Jet Flame ◽  
Lifted Flame ◽  
Auto Ignition ◽  
Lagrangian Tracking

Direct numerical simulation (DNS) of the near field of a three-dimensional spatially developing turbulent lifted hydrogen jet flame in heated coflow is performed with a detailed mechanism to determine the stabilization mechanism and the flame structure. The DNS was performed at a jet Reynolds number of 11,000 with over 940 million grid points. The results show that auto-ignition in a fuel-lean mixture at the flame base is the main source of stabilization of the lifted jet flame. A chemical flux analysis shows the occurrence of near-isothermal chemical chain branching preceding thermal runaway upstream of the stabilization point, indicative of hydrogen auto-ignition in the second limit. The Damköhler number and key intermediate-species behaviour near the leading edge of the lifted flame also verify that auto-ignition occurs at the flame base. At the lifted-flame base, it is found that heat release occurs predominantly through ignition in which the gradients of reactants are opposed. Downstream of the flame base, both rich-premixed and non-premixed flames develop and coexist with auto-ignition. In addition to auto-ignition, Lagrangian tracking of the flame base reveals the passage of large-scale flow structures and their correlation with the fluctuations of the flame base. In particular, the relative position of the flame base and the coherent flow structure induces a cyclic motion of the flame base in the transverse and axial directions about a mean lift-off height. This is confirmed by Lagrangian tracking of key scalars, heat release rate and velocity at the stabilization point.

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