Influence of the Primary Jets and Fuel Injection on the Aerodynamics of a Prototype Annular Gas Turbine Combustor Sector

2010 ◽  
Author(s):  
Bassam Mohammad ◽  
San-Mou Jeng ◽  
M. Gurhan Andac
Keyword(s):  
Flow Field ◽  
Fuel Injection ◽  
Swirling Flow ◽  
Reacting Flow ◽  
Strong Impact ◽  
Convective Cooling ◽  
Fuel Flow ◽  
Flow Field Characteristics ◽  
Order Of Magnitude ◽  
Primary Jets

Transverse dilution jets are widely used in combustion systems. The current research provides a detailed study of the primary jets of a realistic annular combustion chamber sector. The combustor sector comprises an aerodynamic diffuser, inlet cowl, combustion dome, primary dilution jets, secondary dilution jets and cooling strips to provide convective cooling to the liner. The chamber contracts toward the end to fit the turbine nozzle ring. 2D PIV is employed at an atmospheric pressure drop of 4% (isothermal) to delineate the flow field characteristics. The laser is introduced to the sector through the exit flange. The interaction between the primary jets and the swirling flow as well as the sensitivity of the primary jets to perturbations is discussed. The perturbation study includes: effect of partially blocking the jets, one at a time, the effect of blocking the convective cooling holes, placed underneath the primary jets and shooting perpendicular to it. In addition, the effect of reducing the size of the primary jets as well as off-centering the primary jets is explained. Moreover, PIV is employed to study the flow field with and without fuel injection at four different fuel flow rates. The results show that the flow field is very sensitive to perturbations. The cooling air interacts with the primary jet and influences the flow field although the momentum ratio has a 100:1 order of magnitude. The results also show that the big primary jets dictate the flow field in the primary zone as well as the secondary zone. However, relatively smaller jets mainly influence the primary combustion zone because most of the jet is recirculated back to the CRZ. Also, the jet penetration is reduced with 25% and 11.5% corresponding to a 77% and 62% reduction of the jet’s area respectively. The study indicates the presence of a critical jet diameter beyond which the dilution jets have minimum impact on the secondary region. The jet off-centering shows significant effect on the flow field though it is in the order of 0.4 mm. The fuel injection is also shown to influence the flow field as well as the primary jets angle. High fuel flow rate is shown to have very strong impact on the flow field and thus results in a strong distortion of both the primary and secondary zones. The results provide useful methods to be used in the flow field structure control. Most of the effects shown are attributed to the difference in jet opposition. Hence, the results are applicable to reacting flow.

Influence of the Primary Jets and Fuel Injection on the Aerodynamics of a Prototype Annular Gas Turbine Combustor Sector

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Bassam Mohammad ◽  
San-Mou Jeng ◽  
M. Gurhan Andac
Keyword(s):  
Flow Field ◽  
Fuel Injection ◽  
Swirling Flow ◽  
Reacting Flow ◽  
Strong Impact ◽  
Convective Cooling ◽  
Fuel Flow ◽  
Flow Field Characteristics ◽  
Order Of Magnitude ◽  
Primary Jets

Transverse dilution jets are widely used in combustion systems. The current research provides a detailed study of the primary jets of a realistic annular combustion chamber sector. The combustor sector comprises an aerodynamic diffuser, inlet cowl, combustion dome, primary dilution jets, secondary dilution jets, and cooling strips to provide convective cooling to the liner. The chamber contracts toward the end to fit the turbine nozzle ring. 2D PIV is employed at an atmospheric pressure drop of 4% (isothermal) to delineate the flow field characteristics. The laser is introduced to the sector through the exit flange. The interaction between the primary jets and the swirling flow as well as the sensitivity of the primary jets to perturbations is discussed. The perturbation study includes: effect of partially blocking the jets, one at a time, the effect of blocking the convective cooling holes, placed underneath the primary jets and shooting perpendicular to it. In addition, the effect of reducing the size of the primary jets as well as off-centering the primary jets is explained. Moreover, PIV is employed to study the flow field with and without fuel injection at four different fuel flow rates. The results show that the flow field is very sensitive to perturbations. The cooling air interacts with the primary jet and influences the flow field although the momentum ratio has a 100:1 order of magnitude. The results also show that the big primary jets dictate the flow field in the primary zone as well as the secondary zone. However, relatively smaller jets mainly influence the primary combustion zone because most of the jet is recirculated back to the CRZ. Also, the jet penetration is reduced with 25% and 11.5% corresponding to a 77% and 62% reduction of the jet’s area, respectively. The study indicates the presence of a critical jet diameter beyond which the dilution jets have minimum impact on the secondary region. The jet off-centering shows significant effect on the flow field though it is in the order of 0.4 mm. The fuel injection is also shown to influence the flow field as well as the primary jets angle. High fuel flow rate is shown to have very strong impact on the flow field and thus results in a strong distortion of both the primary and secondary zones. The results provide useful methods to be used in the flow field structure control. Most of the effects shown are attributed to the difference in jet opposition. Hence, the results are applicable to reacting flow.

Effect of Dome Geometry on Swirling Flow Field Characteristics of a Counter-Rotating Radial-Radial Swirler

2013 ◽  
Author(s):  
Yi-Huan Kao ◽  
Samir B. Tambe ◽  
San-Mou Jeng
Keyword(s):  
Flow Field ◽  
Flow Structure ◽  
Recirculation Zone ◽  
Swirling Flow ◽  
Aerodynamic Characteristics ◽  
Sudden Expansion ◽  
Reacting Flow ◽  
Clockwise Rotation ◽  
Expansion Angle ◽  
Flow Field Characteristics

An experimental study has been conducted to study the effect of the dome geometry on the aerodynamic characteristics of a non-reacting flow field. The flow was generated by a counter-rotating radial-radial swirler consisting of an inner, primary swirler generating counter-clockwise rotation and an outer, secondary swirler generating clockwise rotation. The dome geometry was modified by introducing dome expansion angles of 60° and 45° with respect to the swirler centerline, in addition to the baseline case of sudden expansion (90°). The flow downstream of the swirler is confined by a 50.8mm × 50.8mm × 304.8mm (2″ × 2″ × 12″) plexiglass chamber. A two-component laser doppler velocimetry (LDV) system was used to measure the velocities in the flow field. The dome geometry is seen to have a clear impact on mean swirling flow structure near the swirler exit rather than the downstream flow field. For the configurations with 60° and 45° expansion, no corner recirculation zone is observed and the swirling flow structure is asymmetric due to the non-axisymmetric dome geometry. The cross-section area of central recirculation zone is larger for dome geometry with 60° expansion angle, as compared to the 90° and 45° cases. The configurations with 60° and 45° expansion have higher magnitudes of negative velocity inside the core of central recirculation zone, as compared to the configuration with 90° expansion angle.

Numerical Investigation of the Flow Field and Mixing in a Swirl-Stabilized Burner With a Non-Swirling Axial Jet

2015 ◽  
Author(s):  
Tom Tanneberger ◽  
Thoralf G. Reichel ◽  
Oliver Krüger ◽  
Steffen Terhaar ◽  
Christian Oliver Paschereit
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Swirling Flow ◽  
High Reactivity ◽  
Water Tunnel ◽  
Reacting Flow ◽  
Mean Flow ◽  
Lean Premixed Combustion ◽  
Mixing Quality ◽  
Flow Field Characteristics

In the present study numerical results of simulations, using RANS and LES, of the non-reacting flow in a swirl-stabilized burner are presented. The burner was developed for lean premixed combustion with high fuel flexibility at low emissions. An important challenge for a fuel-flexible, low emission combustor is the prevention of flashback for fuels of high reactivity, such as hydrogen, without compromising on lean blow out safety and mixing quality. Flashback safety can be increased by a sufficiently high and uniform axial velocity at the end of the mixing tube. In the investigated combustor the velocity deficit in the center of the mixing tube, which results from the swirl, is prevented by a non-swirling axial jet. In a parametric study the effect of different amounts of axial injection on the flow field is investigated. The results are validated with experimental data, gained from PIV measurements in a vertical water tunnel. It is shown that the mean flow field can be well captured by steady-state RANS simulations using a realizable k-ε turbulence model. The most suitable geometry is identified and, subsequently, transient LES simulations are conducted. The dynamic flow field characteristics are investigated. It was found that in spite of the high swirl, the flow field is quite stable and no dominating frequency is detected. The flow field of the swirling flow in the combustion chamber can be captured well using LES. Furthermore, the mixing quality is compared to the experiments, which are performed in a water tunnel. In contrast to the RANS simulation, the LES can qualitatively capture the spatial unmixedness observed from experimental data. All simulations were conducted using water as fluid.

scholarly journals Non-premixed swirl-type tubular flames burning liquid fuels

2018 ◽  
Vol 846 ◽  
pp. 210-239
Author(s):  
Vinicius M. Sauer ◽  
Fernando F. Fachini ◽  
Derek Dunn-Rankin
Keyword(s):  
Flow Field ◽  
Swirling Flow ◽  
Flame Structure ◽  
Flow Analysis ◽  
Liquid Fuels ◽  
Reacting Flow ◽  
Surface Mass ◽  
Surface Mass Transfer ◽  
Incompressible Viscous Flow ◽  
Porous Walls

Tubular flames represent a canonical combustion configuration that can simplify reacting flow analysis and also be employed in practical power generation systems. In this paper, a theoretical model for non-premixed tubular flames, with delivery of liquid fuel through porous walls into a swirling flow field, is presented. Perturbation theory is used to analyse this new tubular flame configuration, which is the non-premixed equivalent to a premixed swirl-type tubular burner – following the original classification of premixed tubular systems into swirl and counterflow types. The incompressible viscous flow field is modelled with an axisymmetric similarity solution. Axial decay of the initial swirl velocity and surface mass transfer from the porous walls are considered through the superposition of laminar swirling flow on a Berman flow with uniform mass injection in a straight pipe. The flame structure is obtained assuming infinitely fast conversion of reactants into products and unity Lewis numbers, allowing the application of the Shvab–Zel’dovich coupling function approach.

Significant of Isothermal Flow Studies for High Swirling Flow in Unconfined Burner

2015 ◽  
Vol 789-790 ◽  
pp. 477-483
Author(s):  
A.R. Norwazan ◽  
M.N. Mohd Jaafar
Keyword(s):  
Flow Field ◽  
Combustion Chamber ◽  
Turbulent Flows ◽  
Recirculation Zone ◽  
Swirling Flow ◽  
Numerical Study ◽  
Tangential Velocity ◽  
Radial Distance ◽  
Navier Stokes ◽  
Reacting Flow

This paper is presents numerical simulation of isothermal swirling turbulent flows in a combustion chamber of an unconfined burner. Isothermal flows of with three different swirl numbers, SN of axial swirler are considered to demonstrate the effect of flow axial velocity and tangential velocity to define the center recirculation zone. The swirler is used in the burner that significantly influences the flow pattern inside the combustion chamber. The inlet velocity, U0 is 30 m/s entering into the burner through the axial swirler that represents a high Reynolds number, Re to evaluate the differences of SN. The significance of center recirculation zone investigation affected by differences Re also has been carried out in order to define a good mixing of air and fuel. A numerical study of non-reacting flow into the burner region is performed using ANSYS Fluent. The Reynolds–Averaged Navier–Stokes (RANS) realizable k-ε turbulence approach method was applied with the eddy dissipation model. An attention is focused in the flow field behind the axial swirler downstream that determined by transverse flow field at different radial distance. The results of axial and tangential velocity were normalized with the U0. The velocity profiles’ behaviour are obviously changes after existing the swirler up to x/D = 0.3 plane. However, their flow patterns are similar for all SN after x/D = 0.3 plane towards the outlet of a burner.

Characterisation of the Instantaneous Velocity and Mixture Field Issuing From a Lean Premixed Module (LPM)

2003 ◽  
Author(s):  
J. F. Carrotte ◽  
C. Batchelor-Wylam
Keyword(s):  
Velocity Field ◽  
Flow Field ◽  
Swirling Flow ◽  
Spectral Characteristics ◽  
Gaseous Fuel ◽  
Constant Current ◽  
Reacting Flow ◽  
Lean Premixed ◽  
Velocity Spectra ◽  
The Individual

Measurements have been made on the non-reacting flow field issuing from a Lean Premixed module (LPM) that incorporates a radial swirler, mixing duct section and nozzle. The geometry contains many features that are thought typical of LPM systems in which gaseous fuel is introduced into a swirling flow at a discrete number of locations. Hot wire anemometry measurements have been used to define the velocity field issuing from the module whilst additional experiments have utilised heated air to simulate gaseous fuel. In this way temperature measurements, using Constant Current Anemometry, have been used to infer the fuel-air mixture field issuing from the module. The velocity data indicates a highly turbulent flow field and the basic spectral characteristics of this velocity field are defined. In addition, within certain regions a strong periodic flow component is observed and is indicative of the instabilities typically associated with swirling flows. The spectral characteristics of the mixture field are also presented and the method by which the mixture and velocity spectra should be compared is outlined. Using this method the measurements indicate the basic spectral characteristics are virtually identical and, furthermore, a periodic fluctuation in the mixture field is also observed. For these types of LPM systems fluctuations in the mixture and velocity fields are therefore strongly correlated. In addition it is shown that the flow fields are dominated by the relatively large time and length scales associated with the main velocity field rather than, say, the much smaller velocity and mixing scales associated with the individual fuel jets.

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.

The Effect of Velocity in High Swirling Flow in Unconfined Burner

2014 ◽  
Vol 69 (6) ◽  
Author(s):  
Norwazan A. R ◽  
Mohammad Nazri Mohd. Jaafar
Keyword(s):  
Flow Field ◽  
Turbulent Flows ◽  
Recirculation Zone ◽  
Swirling Flow ◽  
Numerical Study ◽  
Tangential Velocity ◽  
Reacting Flow ◽  
Ansys Fluent ◽  
Inlet Velocity ◽  
Burner Exit

This paper presents a numerical simulation of swirling turbulent flows in combustion chamber of unconfined burner. Isothermal flows with three different swirl numbers using axial swirler are used to demonstrate the effect of flow in axial velocity and tangential velocity on the center recirculation zone. The significance of center recirculation zone is to ensure a good mixing of air and fuel in order to get a better combustion. The inlet velocity, U0 is 30 m/s entering into the burner through the axial swirler that is represents a high Reynolds number. A numerical study of non-reacting flow in the burner region is performed using ANSYS Fluent. The Reynolds–Averaged Navier–Stokes (RANS) standard k-ε turbulence approach method was applied with the eddy dissipation model. The paper focuses the flow field behind the axial swirler downstream that determined by transverse flow field at different on radial distances. The results of axial and tangential velocity were normalized with the inlet velocity. The velocity profiles are different after undergoing the different swirler up to the burner exit. However, the results of velocity profile showed that the high SN gives a better swirling flow patterns. 

Velocity and Momentum Decay Characteristics of a Submerged Viscoplastic Jet

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Flow Field ◽  
Yield Stress ◽  
Initial Velocity ◽  
Momentum Conservation ◽  
Wide Range ◽  
Velocity Decay ◽  
Flow Field Characteristics ◽  
Order Of Magnitude ◽  
Field Information ◽  
Penetration Depths

Velocity and momentum decay characteristics of a submerged viscoplastic non-Newtonian jet are studied within the steady laminar flow regime. The governing mass and momentum conservation equations along with the Bingham rheological model are solved numerically using a finite-difference scheme. A parametric study is performed to reveal the influence of the initial velocity profile, flow inertia, and yield stress presence on the flow field characteristics. Two initial velocity profiles are considered, a top-hat and fully developed pipe jets. The centerline velocity decay is found to be more rapid for the pipe jet than the top-hat one when the fluid is Newtonian while the opposite trend is observed for yield stress Bingham fluids. The decay in the momentum flux of the pipe jet is always less than that of the top-hat jet. Momentum and velocity based jet depths of penetration are introduced and used to analyze the obtained flow field information for a wide range of Reynolds and yield numbers. Depths of penetration are found to linearly increase with the Reynolds number and substantially decrease with the yield number. The presence of yield stress significantly reduces the momentum and velocity penetration depths of submerged top-hat and pipe jets. Penetration depths of yield stress fluids are shown to be more than an order of magnitude smaller than the ones corresponding to Newtonian fluids.

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