Numerical Investigation of a Lean Premixed Swirl-Stabilized Hydrogen Combustor and Operational Conditions Close to Flashback

2018 ◽  
Author(s):  
D. Mira ◽  
O. Lehmkuhl ◽  
P. Stathopoulos ◽  
T. Tanneberger ◽  
T. G. Reichel ◽  
...  
Keyword(s):  
Flow Field ◽  
Numerical Investigation ◽  
Operating Conditions ◽  
Combustion Model ◽  
Reacting Flow ◽  
Operational Conditions ◽  
Air Jet ◽  
Large Eddy ◽  
Burner Design ◽  
The Eu

The current study presents a numerical investigation of the flow field of a swirl-stabilized burner featuring a non-swirling axial air jet on the central axis of the mixing tube. The system has been designed and optimized to burn hydrogen at the Technische Universität Berlin over the last 6 years in the context of the EU-funded projects GREENEST and AHEAD. As the burner design was based on experimental work, high-fidelity large-eddy simulations (LES) are used to provide deeper understanding on the non-reacting and reacting flow fields to elucidate the occurrence of flashback under certain operating conditions. The experimental measurements suggest that flashback is produced by a velocity deficit at the mixing tube outlet and these conditions are analyzed here using LES. The work includes code validation for non-reacting and reacting conditions by comparison to water tunnel and combustion test rig data, and aims to evaluate the accuracy of LES with a combustion model based on premixed flamelets to predict the reacting flow field under conditions close to flashback.

Experimental and Numerical Investigation of Stator Exit Flow Field of an Automotive Torque Converter

1996 ◽  
Vol 118 (4) ◽  
pp. 835-843 ◽  
Author(s):  
B. V. Marathe ◽  
B. Lakshminarayana ◽  
Y. Dong
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Numerical Investigation ◽  
Three Dimensional ◽  
Axial Flow ◽  
Torque Converter ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Complex Flow ◽  
Rate Of Decay

The objective of this investigation is to understand the nature of the complex flow field inside each element of the torque converter through a systematic experimental and numerical investigation of the flow field. A miniature five-hole probe was used to acquire the data at the exit of the stator at several operating conditions. The flow field is found to be highly three dimensional with substantial flow deviations, and secondary flow at the exit of the stator. The secondary flow structure, caused by the upstream radial variation of the through flow, induces flow overturning near the core. Flow separation near the shell causes flow underturning in this region. The rate of decay of stator wake is found to be slower than that observed in the wakes of axial flow turbine nozzles. The flow predictions by a Navier–Stokes code are in good agreement with the pressure and the flow field measured at the exit of the stator at the design and the off-design conditions.

Numerical Characterisation of a Gas Turbine Model Combustor Applying Scale-Adaptive Simulation

2009 ◽  
Author(s):  
Axel Widenhorn ◽  
Berthold Noll ◽  
Manfred Aigner
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Mixture Fraction ◽  
Thermal Power ◽  
Three Dimensional ◽  
Combustion Model ◽  
Reacting Flow ◽  
Adaptive Simulation ◽  
Power Load ◽  
Turbine Model

In this contribution the three-dimensional reacting turbulent flow field of a swirl-stabilized gas turbine model combustor is analyzed numerically. The investigated partially premixed and lifted CH4/air flame has a thermal power load of Pth = 35kW and a global equivalence ratio of φ = 0.65. To study the reacting flow field the Scale Adaptive Simulation (SAS) turbulence model in combination with the Eddy Dissipation/Finite Rate Chemistry combustion model was applied. The simulations were performed using the commercial CFD software package ANSYS CFX-11.0. The numerically achieved time-averaged values of the velocity components and their appropriate turbulent fluctuations (RMS) are in very good agreement with the experimental values (LDA). The same excellent results were found for other flow quantities like temperature and mixture fraction. Here, the corresponding time-averaged and the appropriate RMS profiles are compared to Raman measurements. Furthermore the instantaneous flow features are discussed. In accordance with the experiment the numerical simulation evidences the existence of a precessing vortex core (PVC). The PVC rotates with a frequency of 1596Hz. Moreover it is shown that in the upper part of the combustion chamber a tornado-like vortical structure is established.

Numerical Investigation on Visualizations of Confined Air Flow in a Slot Jet Inside a Rectangular Channel

2015 ◽  
Vol 813-814 ◽  
pp. 736-741
Author(s):  
M. Muthukannan ◽  
P. Rajesh Kanna ◽  
S. Jeyakumar ◽  
J.Y. Raja Shangaravel ◽  
S. Raghu ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Numerical Investigation ◽  
Rectangular Channel ◽  
Reynolds Numbers ◽  
Vortex Center ◽  
Computational Domain ◽  
Reattachment Length ◽  
Aspect Ratios ◽  
Air Jet

In the present numerical investigation, the flow field of confined slot air jet in a rectangular computational domain is reported. In the present work the flow field parameters like reattachment length, vortex center and horizontal velocity profiles for various Reynolds numbers and for various aspect ratios are presented .The present study reveals that the vortex centers are moving in a downstream direction with increase in Reynolds number. The reattachment length is directly dependent on the Reynolds numbers. In case of vortex dynamics, the vortex size is indirectly dependent on the inlet jet width. In the present investigation, SIMPLE algorithm is used to solve the governing equations. It is concluded that the aspect ratio and the Reynolds number are playing dominant roles in flow field of the present computational domain.

A NOx Prediction Scheme for Lean-Premixed Gas Turbine Combustion Based on Detailed Chemical Kinetics

1996 ◽  
Vol 118 (4) ◽  
pp. 765-772 ◽  
Author(s):  
W. Polifke ◽  
K. Do¨bbeling ◽  
T. Sattelmayer ◽  
D. G. Nicol ◽  
P. C. Malte
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Concentration Field ◽  
Operating Conditions ◽  
Chemical Mechanism ◽  
Reacting Flow ◽  
Oxides Of Nitrogen ◽  
Detailed Chemical Kinetics ◽  
Nox Formation ◽  
Lean Premixed

The lean-premixed technique has proven very efficient in reducing the emissions of oxides of nitrogen (NOx) from gas turbine combustors. The numerical prediction of NOx levels in such combustors with multidimensional CFD codes has only met with limited success so far. This is to some extent due to the complexity of the NOx formation chemistry in lean-premixed combustion, i.e., all three known NOx formation routes (Zeldovich, nitrous, and prompt) can contribute significantly. Furthermore, NOx formation occurs almost exclusively in the flame zone, where radical concentrations significantly above equilibrium values are observed. A relatively large chemical mechanism is therefore required to predict radical concentrations and NOx formation rates under such conditions. These difficulties have prompted the development of a NOx postprocessing scheme, where rate and concentration information necessary to predict NOx formation is taken from one-dimensional combustion models with detailed chemistry and provided—via look-up tables—to the multidimensional CFD code. The look-up tables are prepared beforehand in accordance with the operating conditions and are based on CO concentrations, which are indicative of free radical chemistry. Once the reacting flow field has been computed with the main CFD code, the chemical source terms of the NO transport equation, i.e., local NO formation rates, are determined from the reacting flow field and the tabulated chemical data. Then the main code is turned on again to compute the NO concentration field. This NOx submodel has no adjustable parameters and converges very quickly. Good agreement with experiment has been observed and interesting conclusions concerning superequilibrium O-atom concentrations and fluctuations of temperature could be drawn.

scholarly journals NUMERICAL INVESTIGATION OF A TONE NOISE OF THE FAN WITH CASING TREATMENT

2021 ◽  
pp. 24-38
Author(s):  
Yaroslav Druzhinin ◽  
◽  
Viktor Mileshin ◽  
Anton Rossikhin ◽  
◽  
...  
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Numerical Investigation ◽  
Significant Influence ◽  
Aerodynamic Characteristics ◽  
Operational Conditions ◽  
Casing Treatment ◽  
Harmonic Method ◽  
Surge Line ◽  
Bypass Ratio

Numerical investigation of influence of a slot-type casing treatment on acoustic and aerodynamic characteristics of the fan of ultra-high bypass ratio turbofan is presented. The investigation was performed using NUMECA FINE/Turbo solver. NLH harmonic method was used to simulate the effect of casing treatment on unsteady flow field in the turbomachine. Two operational conditions were investigated – “sideline” and “approach”. The attention for the first operational condition was paid for aerodynamic characteristics. Significant influence of casing treatment on them was found especially near the surge line. At the “approach” operational conditions the attention was paid for the proper calculation of tone noise. It was shown that the installation of casing treatment leads to decrease of power of tone noise radiated through the inlet. However the power of the tone noise, radiated through the nozzle, and also the overall power of tone noise increase.

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 Study of the Wall Thermal Condition Effect in a Lean-Premixed Downscaled Can Combustor Using Large-Eddy Simulation

2016 ◽  
Author(s):  
D. Mira ◽  
M. Vázquez ◽  
G. Houzeaux ◽  
S. Gövert ◽  
J. W. B. Kok ◽  
...  
Keyword(s):  
Turbulent Combustion ◽  
Mixture Fraction ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Laminar Flames ◽  
Combustion Model ◽  
Test Case ◽  
Eddy Simulation ◽  
Condition Effect ◽  
Large Eddy

The primary purpose of this study is to evaluate the ability of LES, with a turbulent combustion model based on steady flamelets, to predict the flame stabilization mechanisms in an industrial can combustor at full load conditions. The test case corresponds to the downscaled Siemens can combustor tested in the high pressure rig at the DLR. The effects of the wall temperature on the prediction capabilities of the codes is investigated by imposing several heat transfer conditions at the pilot and chamber walls. The codes used for this work are Alya and OpenFOAM, which are well established CFD codes in the fluid mechanics community. Prior to the simulation, results for 1-D laminar flames at the operating conditions of the combustor are compared with the detailed solutions. Subsequently, results from both codes at the mid-plane are compared against the experimental data available. Acceptable results are obtained for the axial velocity, while discrepancies are more evident for the mixture fraction and the temperature, particularly with Alya. However, both codes showed that the heat losses influence the size and length of the pilot and main flame.

Turning Mid Turbine Frame Behavior for Different HP Turbine Outflow Conditions

2011 ◽  
Author(s):  
Berardo Paradiso ◽  
Cornelia Santner ◽  
Josef Hubinka ◽  
Emil Go¨ttlich ◽  
Martin Hoeger
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Pressure Ratio ◽  
Measurement Techniques ◽  
Operating Conditions ◽  
Time Resolved ◽  
Flow Angle ◽  
The Mean ◽  
Eu Project ◽  
The Eu

The design of turbine frames with turning vanes, known as turning mid-turbine frames (TMTF), becomes of great importance for high by-pass ratio engines with counter-rotating turbines. To achieve a more efficient low-pressure turbine the overall diffusion and radial offset should be increased. One goal of the EU project DREAM is to analyse the flow through a TMTF and a downstream arranged counter rotating LP rotor. The investigation of these complex interrelationships has been performed in the unique two-spool continuously operating transonic test turbine facility at Graz University of Technology. The test setup consists of an unshrouded HP stage, the TMTF and a shrouded LP rotor. The shafts of both turbines are mechanically independent, so the test rig allows a realistic two shaft turbine operation. The TMTF flow field is highly complex. It is a turbulent and unsteady flow dominated by strong secondary flows and vortex-interactions. The upstream transonic high pressure turbine stage produces a complex inflow with high levels of turbulence, stationary and rotating wakes and vortical structures. Therefore the application of advanced measurement techniques is necessary. To describe the HP-TMTF interaction time-resolved pressure measurements have applied within the project. The TMTF was instrumented with 10 fast response pressure transducers; static pressure tap recordings on the strut and on the TMTF end-walls have been also applied. Five hole probe, total pressure and total temperature rakes have been additionally acquired in the planes just in front of the struts and downstream to evaluate the performance of the TMTF. The results of these conventional techniques are presented in this work and they represent the necessary starting point for the evaluation and the description of the flow field. The idea is to start the study analysing the mean quantities and the overall performance of the two stages for different conditions and to leave the analysis of the time-resolved results for further investigation. Detailed investigations will start from the data presented in this paper; indeed, the use of unsteady measurement techniques is time consuming and cannot be performed for such a large amount of flow conditions, radial planes and HP vane - TMTF relative positions. Three operating conditions for different clocking positions have been considered. The variation of the operating conditions has been achieved by varying the HP shaft velocity and pressure ratio, with a consequence change of pressure ratio in the LP rotor. For this analysis the LP shaft velocity was kept constant. The TMTF performance variations will be analysed in terms of total pressure loss coefficient and exit flow angle; the mean interaction between the structures coming from the HP stage and the struts will represent the interpretation key to explain these variations. This work is part of the EU project DREAM (ValiDation of Radical Engine Architecture SysteMs, contract No. ACP7-GA-2008-211861).

scholarly journals Numerical investigation of a novel burner to combust anode exhaust gases of SOFC stacks

2017 ◽  
Vol 19 (3) ◽  
pp. 20-26 ◽  
Author(s):  
Paulina Pianko-Oprych ◽  
Zdzisław Jaworski
Keyword(s):  
Numerical Investigation ◽  
Combustion Process ◽  
Operating Conditions ◽  
Exhaust Gases ◽  
Technical Requirements ◽  
Combustion Modelling ◽  
Burner Design ◽  
Novel Concept ◽  
Numerical Optimisation ◽  
Sofc Stacks

Abstract The aim of the present study was a numerical investigation of the efficiency of the combustion process of a novel concept burner under different operating conditions. The design of the burner was a part of the development process of a complete SOFC based system and a challenging combination of technical requirements to be fulfilled. A Computational Fluid Dynamics model of a non-premixed burner was used to simulate combustion of exhaust gases from the anode region of Solid Oxide Fuel Cell stacks. The species concentrations of the exhaust gases were compared with experimental data and a satisfactory agreement of the conversion of hydrocarbons was obtained. This validates the numerical methodology and also proves applicability of the developed approach that quantitatively characterized the interaction between the exhaust gases and burner geometry for proper combustion modelling. Thus, the proposed CFD approach can be safely used for further numerical optimisation of the burner design.

Reynolds Analog in Combustor Modeling

2007 ◽  
Author(s):  
Lei-Yong Jiang ◽  
Ian Campbell
Keyword(s):  
Schmidt Number ◽  
Scalar Fields ◽  
Reacting Flows ◽  
Operating Conditions ◽  
Combustion Model ◽  
Reacting Flow ◽  
Turbulent Reacting Flows ◽  
Reynolds Analogy ◽  
Experimental Database ◽  
Advanced Combustion

Accurate temperature prediction is vital for the development of advanced combustion systems. The Reynolds analogy concept has been almost exclusively used in current turbulent reacting flow RANS simulations. In this paper, this hypothesis applied to a diffusion flame model combustor is discussed and assessed. Some of the numerical results obtained from a flamelet combustion model with the turbulence Prandtl/Schmidt number from 0.25 to 0.85 are presented, and compared with a benchmark experimental database. It is found that the turbulence Prandtl/Schmidt number has significant effect on the predicted temperature and species fields inside the combustor, as well as the temperature profile at the combustor wall. In contrast, its effect on the velocity field is insignificant in the range assessed. With the optimized turbulence Prandtl/Schmidt number, both velocity and scalar fields can be reasonably and quantitatively predicted. For the present configuration and operating conditions, the optimal Prandtl/Schmidt number is 0.5, lower than the commonly accepted values, ∼0.70. This study suggests that for accurate prediction of scalar transfers in turbulent reacting flows, the Reynolds analogy concept should be improved and new approaches should be developed.

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