Investigation of the Reacting Flow Field of a Lean Burn Injector With Varying Degree of Swirl at Elevated Pressure Condition

2017 ◽  
Author(s):  
Christoph Hassa ◽  
Ulrich Meier ◽  
Johannes Heinze ◽  
Eggert Magens ◽  
Michael Schroll ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Flow Field ◽  
Soot Formation ◽  
Combustion Process ◽  
Experimental Studies ◽  
Elevated Pressure ◽  
Mie Scattering ◽  
Reacting Flow ◽  
Soot Emission ◽  
Lean Burn

Two RR Lean Direct Injection (LDI) injector versions with different amounts of pilot swirl were investigated. Experiments, performed at elevated pressure and temperature, corresponding to engine conditions at idle include Mie scattering. LII and absorption measurements are used for soot concentration within the primary zone. The soot emission at the outlet is measured by an SMPS instrument. These experimental studies are complemented with PIV measurements. The acquired data allows evaluation of the combustion process from the liquid phase, followed by evaporation, reaction and finally soot production with high spatial resolution. The change of swirl produced rather moderate changes in the flow field, nevertheless qualitative changes in the fuel placement were observed. Starting from there, differences in heat release and soot formation can be explained, which lead to larger changes of soot emission. These observations show that a good knowledge of the interaction of gas and liquid phase is necessary to predict the occurrence of behavioral changes in the operating regime.

Characterization of Lean Burn Module Air Blast Pilot Injector With Laser Techniques

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
U. Meier ◽  
S. Freitag ◽  
J. Heinze ◽  
L. Lange ◽  
E. Magens ◽  
...  
Keyword(s):  
Flow Field ◽  
Soot Formation ◽  
Test Methods ◽  
Oh Radicals ◽  
Main Stage ◽  
Fuel Injector ◽  
Lean Burn ◽  
Fuel Ratio ◽  
Optical Test ◽  
Planar Laser

For lean burn combustor development in low emission aero-engines, the pilot stage of the fuel injector plays a key role with respect to stability, operability, NOx emissions, and smoke production. Therefore it is of considerable interest to characterize the pilot module in terms of pilot zone mixing, fuel placement, flow field, and interaction with the main stage. This contribution focuses on the investigation of soot formation during pilot-only operation. Optical test methods were applied in an optically accessible single sector rig at engine idle conditions. Using planar laser-induced incandescence (LII), the distribution of soot and its dependence on air/fuel ratio, as well as geometric injector parameters, was studied. The data shows that below a certain air/fuel ratio, an increase of soot production occurs. This is in agreement with smoke number measurements in a standard single sector flame tube rig without optical access. Reaction zones were identified using chemiluminescence of OH radicals. In addition, the injector flow field was investigated with PIV. A hypothesis regarding the mechanism of pilot smoke formation was made based on these findings. This along with further investigations will form the basis for developing strategies for smoke improvement at elevated pilot-only conditions.

Experimental Investigation of a RQL Burner With Jet in Cross Flow Fuel Injection: Characterization of the Reacting Flow Field at Realistic Operating Conditions

2019 ◽  
Author(s):  
T. Soworka ◽  
T. Behrendt ◽  
C. Hassa ◽  
J. Heinze ◽  
E. Magens ◽  
...  
Keyword(s):  
Flow Field ◽  
Fuel Injection ◽  
Measurement Techniques ◽  
Cross Flow ◽  
Mie Scattering ◽  
Operating Conditions ◽  
Reacting Flow ◽  
Axial Location ◽  
Primary Zone ◽  
Jet In Cross Flow

Abstract Future rich-burn/quick-quench/lean-burn (RQL) burners for aero engines face the challenge to further reduce the emission of soot. Alternative ways of fuel injection are therefore in the focus of modern RQL combustion systems. This contribution aims to investigate experimentally the influence of fuel injection on the reacting flow field, with the emphasis on soot production in the primary zone. For the test, a Rolls-Royce prototype burner was used in two different configurations which differ only in the axial location of jet in cross flow fuel injection and thereby provoke different ways of fuel atomization. In the upstream configuration the burner features characteristics of a pre-filming airblast atomizer. Whereas with the fuel tip in downstream position solely Jet-in-Cross-Flow fuel atomisation is expected. The burner was tested at realistic aero engine combustor conditions (p30 = 9.28 bar, T30 = 603 K, AFR = 7.6). Several optical measurement techniques were used to characterise the reacting flow field. Their difficult application in a rich burn environment is described briefly. The structure of the reacting flow field is illustrated by Particle-Image-Velocimetry (PIV). Planar Mie scattering and Planar Laser-Induced Fluorescence (PLIF) are used to characterise the placement of liquid and gaseous fuel respectively. The location and structure of heat release zones are captured in terms of OH* and CO2* chemiluminescence. Finally Laser-Induced-Incandescence (LII) is used to obtain three dimensional soot distributions in the primary zone. On this basis 20% less soot was measured for the upstream configuration at the axial location of maximal soot concentration. This remarkable difference could be attributed to the different placement of liquid fuel and the resulting better mixing.

scholarly journals Assessment of impinged flame structure in high-pressure direct diesel injection

2019 ◽  
Vol 21 (2) ◽  
pp. 391-405 ◽  
Author(s):  
Zhihao Zhao ◽  
Xiucheng Zhu ◽  
Jeffrey Naber ◽  
Seong-Young Lee
Keyword(s):  
Soot Formation ◽  
Near Field ◽  
Flame Structure ◽  
Combustion Process ◽  
Injection Pressure ◽  
Flux Measurement ◽  
Air Entrainment ◽  
Mie Scattering ◽  
Local Flow ◽  
Spray Impingement

Spray impingement often occurs during cold-start in direct-injection diesel engines, affecting the subsequent combustion process by altering the local flow condition. This work has investigated the impinged flame structure by examining local expansion distance and planar curvature of the boundary in details. The experiments were carried out in a constant volume combustion chamber. The injection pressure and ambient density were varied from 120 to 180 MPa and 14.8 to 30.0 kg/m3 under non-vaporizing conditions, respectively. For reacting conditions, the injection pressure and ambient density were fixed at 150 MPa and 22.8 kg/m3 but with different ambient temperatures from 800 to 1000 K. Unlike orthogonal spray impingement, the profile of expansion distance along the radial direction at the 60° impinging angle is non-uniform but the profile is comparable between the non-vaporizing and reacting conditions under the same injection pressure and ambient density. With the help of Intensity-aXial-Time method, the most intensive soot luminosity region and Mie scattering intensity region are identified and the region has been found to be along the impinged spray axial direction. Outmost boundary of an impinged flame is found to have wrinkles attributed to air entrainment. The temporal level of flame wrinkles is higher in reacting conditions than in non-vaporizing conditions. The scatter distribution of the boundary curvature and near-field soot formation illustrates an inverted “S” shape correlation with time. High flame luminosity is found to be formed in concave regions while less soot is formed in convex regions. This inverted S-shape is a new finding of the state relationship at the solid–liquid–gas impinged flame propagation. Finally, heat flux measurement through the plate is examined.

scholarly journals Experimental Investigation on NO Pollutant Formation in High-Pressure Swirl-Stabilized Kerosene/Air Flames Using NO-, OH- and Kerosene-PLIF and PIV Laser Diagnostics

2020 ◽  
Author(s):  
E. Salaün ◽  
F. Frindt ◽  
G. Cabot ◽  
B. Renou ◽  
S. Richard ◽  
...  
Keyword(s):  
Laser Diagnostics ◽  
Flame Structure ◽  
Combustion Process ◽  
Experimental Studies ◽  
Elevated Pressure ◽  
Injection System ◽  
Inlet Temperature ◽  
No Production ◽  
Air Inlet ◽  
No Formation

Abstract A Lean Premixed injection system (LP) was experimentally investigated at elevated pressure and air inlet temperature, corresponding to engine conditions, i.e. with high swirl number and elevated fresh gases velocities. OH-PLIF, NO-PLIF and kerosene-PLIF laser diagnostics were used to study the flame structure and the NO formation within the primary zone. These experimental studies were complemented with PIV measurements. The acquired data allows the evaluation of the coupling of aerodynamics with the flame structure. Starting from there, the combustion process governing the formation of NO pollutant into the flame was analyzed with high spatial resolution. The Zeldovich pathway has been found to control the NO formation in the inner recirculation zone while the nitrous oxide pathway is found to be important especially in the regions in which the residence time of burnt gases is small. Effect of pressure and FAR also produced significant changes in the NO production. It does appear, however that no universal behavior can be found for the pressure dependence of NO.

Characterisation of Lean Burn Module Air Blast Pilot Injector With Laser Techniques

2013 ◽  
Author(s):  
U. Meier ◽  
S. Freitag ◽  
J. Heinze ◽  
L. Lange ◽  
E. Magens ◽  
...  
Keyword(s):  
Flow Field ◽  
Soot Formation ◽  
Test Methods ◽  
Oh Radicals ◽  
Main Stage ◽  
Fuel Injector ◽  
Lean Burn ◽  
Fuel Ratio ◽  
Optical Test ◽  
Planar Laser

For lean burn combustor development in low emission aero-engines, the pilot stage of the fuel injector plays a key role with respect to stability, operability, NOx emissions, and smoke production. Therefore it is of considerable interest to characterize the pilot module in terms of pilot zone mixing, fuel placement, flow field and interaction with the main stage. This contribution focusses on the investigation of soot formation during pilot-only operation. Optical test methods were applied in an optically accessible single sector rig at engine idle conditions. Using planar laser-induced incandescence (LII), the distribution of soot and its dependence on air/fuel ratio, as well as geometric injector parameters, was studied. The data shows that below a certain air/fuel ratio, an increase of soot production occurs. This is in agreement with smoke number measurements in a standard single sector flame tube rig without optical access. Reaction zones were identified using chemiluminescence of OH radicals. In addition, the injector flow field was investigated with PIV. A hypothesis regarding the mechanism of pilot smoke formation was made based on these findings. This along with further investigations will form the basis for developing strategies for smoke improvement at elevated pilot only conditions.

CFD prediction of the reacting flow field inside a subscale scramjetcombustor

1988 ◽  
Author(s):  
T. CHITSOMBOON ◽  
G. NORTHAM ◽  
R. ROGERS ◽  
G. DISKIN
Keyword(s):  
Flow Field ◽  
Reacting Flow

EXPERIMENTAL STUDIES ON THE CORROSION OCCURRENCE DURING BIOMASS COMBUSTION PROCESS

2012 ◽  
Vol 11 (9) ◽  
pp. 1555-1560 ◽  
Author(s):  
Ionel Pisa ◽  
Gheorghe Lazaroiu ◽  
Corina Radulescu ◽  
Lucian Mihaescu
Keyword(s):  
Combustion Process ◽  
Experimental Studies ◽  
Biomass Combustion

scholarly journals Influence of a Standing Wave Flow-Field on the Dynamics of a Spray Diffusion Flame

Fluids ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 27
Author(s):  
J. Barry Greenberg ◽  
David Katoshevski
Keyword(s):  
Liquid Phase ◽  
Flow Field ◽  
Standing Wave ◽  
Diffusion Flame ◽  
Stokes Number ◽  
Flame Height ◽  
Wave Flow ◽  
Two Dimensional ◽  
Governing Equations ◽  
First Time

A theoretical investigation of the influence of a standing wave flow-field on the dynamics of a laminar two-dimensional spray diffusion flame is presented for the first time. The mathematical analysis permits mild slip between the droplets and their host surroundings. For the liquid phase, the use of a small Stokes number as the perturbation parameater enables a solution of the governing equations to be developed. Influence of the standing wave flow-field on droplet grouping is described by a specially constructed modification of the vaporization Damkohler number. Instantaneous flame front shapes are found via a solution for the usual Schwab–Zeldovitch parameter. Numerical results obtained from the analytical solution uncover the strong bearing that droplet grouping, induced by the standing wave flow-field, can have on flame height, shape, and type (over- or under-ventilated) and on the existence of multiple flame fronts.

scholarly journals Simulation of Thermal Effects on the Flow Field in a Pilot-Scale Kiln

2021 ◽  
Author(s):  
I. A. Sofia Larsson ◽  
Anna-Lena Ljung ◽  
B. Daniel Marjavaara
Keyword(s):  
Flow Field ◽  
Coal Combustion ◽  
Thermal Effects ◽  
Iron Ore ◽  
Combustion Process ◽  
Pilot Scale ◽  
Mixing Properties ◽  
Process Gas ◽  
Mixing Rates ◽  
Computational Fluid Dynamics Cfd

AbstractThe flow field and coal combustion process in a pilot-scale iron ore pelletizing kiln is simulated using a computational fluid dynamics (CFD) model. The objective of the work is to investigate how the thermal effects from the flame affect the flow field. As expected, the combustion process with the resulting temperature rise and volume expansion leads to an increase of the velocity in the kiln. Apart from that, the overall flow field looks similar regardless of whether combustion is present or not. The flow field though affects the combustion process by controlling the mixing rates of fuel and air, governing the flame propagation. This shows the importance of correctly predicting the flow field in this type of kiln, with a large amount of process gas circulating, in order to optimize the combustion process. The results also justify the use of down-scaled, geometrically similar, water models to investigate kiln aerodynamics in general and mixing properties in particular. Even if the heat release from the flame is neglected, valuable conclusions regarding the flow field can still be drawn.

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