Chair of Fluid Dynamics

The team develops and tests methods for the simulation and optimization of reactive flows and flames in installations such as heavy-duty gas turbines, nanoparticle synthesis reactors, piston engines or biomass- and pulverised coal furnaces. Our methods allow for shortened development times to further reduce costs. Our research helps to develop cost-effective, flexible and safe systems which emit fewer pollutants.

The complex processes in synthesis reactors and combustors require a detailed numerical characterisation of reaction and transport processes. Their simulation provides insights into areas, which are inaccessible to experiments, enables the investigation and comprehension of isolated subprocesses, and their interactions, and helps to bridge the gap between lab and industrial scale. For this purpose we develop and implement numerical models and methods which are necessary to describe and simulate turbulent combustion of multiphase flows as well as reaction kinetics.

Our work is financed by the state of North Rhine-Westphalia, the German Research Foundation (DFG), the Federal Ministry of Economics and Technology (BMWi), the Alliance for industrial research (AiF), national and international supercomputing centres as well as multiple private companies.

At the University of Duisburg-Essen, our group is closely linked with other groups at CeNIDE (Center for Nano-Integration Duisburg-Essen), CER.UDE (Center for Energy Research) and CCSS (Center for Computational Sciences and Simulation). As a menber of the IVG, we provide detailed simulation results and utilize data from the experiments of the other groups, which are essential for us.

The study at the chair imparts competences in the fields of flow simulation, in the description of reacting flows and in turbulence modeling.

23.08.2019 Jürgen Warnatz Award 2019

Our former doctoral student and postdoc, Dr. Martin Rieth, receives the Jürgen Warnatz Award 2019 from the German Section of the Combustion Institute for outstanding achievements in the field of combustion research. We are very proud of this achievement - congratulations, Martin!

14.08.2019 Fluid Mechanics 1 Exam - Room Allocation

You can now find the valid list of attendees with room allocation for the exam „Fluid mechanics 1“ dated on the 20th of August 2019 under Teaching.

20.11.2018 Publication accepted in Flow, Turbulence and Combustion

A uniform Gaussian filter has been applied explicitly to the LES conservation equations to simulate a piloted non-premixed methane-air flame (Sandia Flame D). Overall, consistent results have been achieved at a cost that is moderate with implicit or explicit filtering.

07.10.2018 New publication in Shock Waves

In this work, the influence of non-ideal effects on the ignition-delay time and the ignition mechanism of a stoichiometric H2/O2 mixture in a shock tube was investigated. A time-varying state was observed behind the reflected shock, which led to a forced ignition in the case under study. Shock Waves (2018) 1-11

17.09.2018 New publication in Physics of Fluids

The physical mechanisms responsible for flame curvature evolution of a methane-air premixed flame attached to a bluff-body burner have been investigated. The contributions to the mean curvature generation due to the fluid flow motion and to a combination of flow and flame propagation induced strain rates have been analyzed in detail and dominant contributions in different zones of the flame have been identified. Phys. Fluids 30:9 (2018) 095101

10.09.2018 Publication accepted in Combustion and Flame

In this work, a hybrid method is presented that efficiently combines the method of the transported probability density function with the assumed probability density function method. The much more detailed and accurate transported probability density function is used only where it is actually needed, so that the simulation gets by with less computation time without sacrificing accuracy. In the work, the process is tested on a piloted partially premixed flame and its performance is demonstrated.

24.07.2018 New publication in Proceedings of the Combustion Institute

In the present study we compare experimentally obtained temperature and semi-quantified SiO-concentration profiles in low- pressure (3 kPa), lean ( φ <0.6), inert-gas diluted H2 /O2 /Ar burner-stabilized flat flames doped with 200– 4000 ppm hexamethyldisiloxane (HMDSO) or tetramethylsilane (TMS) with results from new developed kinetics modeling. Modeling initial cluster formation is important in this study to unravel the observed ‘double-peak’-structure of the SiO concentration profiles assumed to originate from resublimed SiO from early-formed SiO2 nanoparticles in the rising temperature gradient during initial particle nucleation, and which may be altered by the availability of oxygen in the precursor species.

16.07.2018 Publication accepted in Proceedings of the Combustion Institute

This work aims at examining scalar and enstrophy interfaces in a turbulent premixed flame stabilized behind a bluff-body and comparing the flame displacement speed and the local entrainment velocity. The present investigation sheds some light on the nature of flame stabilization. 

02.07.2018 New publication in Chemical Engineering Transactions

This paper compares the ignition and combustion of biomass with the combustion of coal in a compact and well defined three-dimensional computational setup by means of direct numerical simulation. The operating conditions for coal and biomass are selected to be close to each other to allow for a focused study of the differences in volatile ignition between coal and biomass, which will help future improvement of combustion models targeted to biomass or co-firing combustion systems.Chem Eng Trans. 65 (2018) 37-42

20.06.2018 Publication accepted in Combustion and Flame

Background-oriented schlieren (BOS) imaging was combined with computed tomography to reconstruct the refractive index field within a flame directly in 3D. The technique was first applied to a highly turbulent swirl flame phantom (exactly known field generated by large-eddy simulation) to perform an extensive parameter study. An unsteady Bunsen flame was experimentally targeted and the refractive index field for the instantaneous and time averaged BOS measurements was reconstructed. The results were compared with computed tomography of chemilumiescence (CTC) reconstructions of the flame shape that were based on flame chemiluminescence images, and Bunsen flame simulations.

 

15.06.2018 New publication in Fuel

This research aims at gaining new knowledge for understanding the Moderate and Intense Low oxygen Dilution (MILD) combustion using the Chemical Explosive Mode Analysis (CEMA). This study uses high fidelity large eddy simulations of a Jet-in-Hot-Coflow burner in MILD combustion regime, at different oxygen concentration levels in the hot co-flow, with detailed chemistry to resolve important details of the fuel oxidation reactions. Fuel 232

05.06.2018 Publication accepted in International Journal of Chemical Kinetics

Based on the quantum-chemical calculations for the thermodynamic data of 22 stable silicon-organic species, a complete set of 24 Si- and C-atom-centered, single-bonded and non-radical group-additivity values (GAV) for enthalpy of formation, standard entropy, and heat capacity at temperatures from 200 to 4000 K is derived through unweighted multivariate linear regression.

30.05.2018 Publication accepted in Proceedings of The Combustion Institute

In this paper, we provide an a-priori and a-posteriori analysis of a steady flamelet/progress variable (FPV) approach for pulverized coal flames using direct numerical simulation data. The results validate the FPV approach in a complex configuration and can help to improve combustion modeling for pulverized coal furnaces.

24.05.2018 Computational time granted on Cray XC40 at HLRS

We have been awarded with a grant of 48 million core-hours to conduct massively parallel Direct Numerical Simulations of pulsating turbulent flames on Cray XC40 at the HLRS Supercomputing Centre. Project GCS-JFLA Coordinated by Eray Inanc and Prof. Andreas Kempf.

15.05.2018 Paper accepted and selected as „Editor’s Pick“ by Physics of Fluids

The statistics of reactive scalar gradient and associated strain rates have been investigated in a bluff body stabilized premixed flame configuration using a high-fidelity simulation database. The findings of this analysis are of pivotal importance for the development of accurate combustion models.

04.05.2018 "Publication" in Panini scrapbook

The photo of the lab work of our former colleague Dr. Weise was published as a two-part sticker: C. Weise, Schwarzes Gold, Panini, Picture 111-112, 2018 (Impact Factor = 0).

16.03.2018 New publication in Flow, Turbulence and Combustion

This research aims at gaining some physical insight into the problem of scalar mixing, following the time evolution of propagating iso-surfaces. A rigorous kinematic analysis of non-material line, surface and volume elements, related to propagating iso-scalar surfaces, is presented; this formalism is valid for both constant and variable density flows.Flow, Turbulence and Combustion, 1-32

08.02.2018 Martin Rieth has successfully passed his doctoral examination

Martin has successfully passed his examination on "Large Eddy and Direct Numerical Simulation of Single and Multiphase Flows Relying on Lagrangian Particle Methods". Congratulations!

29.11.2017 New publication in Fuel

The non-premixed steady flamelet model is extended by two simple, robust and effective heat loss modelling approaches. The heat release damping (HRD) approach decreases the chemical source term in the energy equation by a constant factor, while the artificial radiation (AR) approach introduces an augmented temperature dependent radiative source term. The models are tested in a simulation of the 0.78 MWth IFRF (International Flame Research Foundation) pilot scale, non-premixed, natural gas/oxygen flame. The heat loss modelling yields a significant improvement in every quantity over the classical adiabatic flamelet model.Fuel 216 (2018)

26.10.2017 New publication in Combustion Science and Technology

The influence of the global Lewis number, Le, on the statistical behavior of the 'effective' normal and tangential strain rates have been analyzed based on three-dimensional DNS data of freely propagating statistically planar turbulent premixed flames with Le = 0.34, 0.60, 0.80, 1.00 and 1.20.  It has been found that turbulent flames with small values of Lewis number exhibit flame thinning and high values of the flame surface area and these tendency strengthens with decreasing Lewis number.Combustion Science and Technology (2017)

January 2018: We sadly mourn for Olaf Hasemann, who died after a serious illness on December 23rd, 2018

29.11.2017: Publication accepted in Fuel: P. Wollny,  B. Rogg, A. M. Kempf (2017), Modelling Heat Loss Effects in High Temperature Oxy-Fuel Flames with an Efficient and Robut Non-Premixed Flamelet Approach

26.10.2017: Publication accepted in Combustion Science and Technology: Dopazo, Cifuentes, Alwazzan, Chakraborty (2017), Influence of the Lewis number on effective strain rates in weakly turbulent premixed combustion

25.10.2017: Andreas Rittler has successfully passed his doctoral examination. Thesis "Large eddy simulation of nanoparticle synthesis from spray flames". Congratulations Andreas!

27.09.2017: Publication accepted in Fuel: M. Rieth, A.M. Kempf, A. Kronenburg, O.T. Stein (2017), Carrier-phase DNS of pulverized coal particle ignition and volatile burning in a turbulent mixing layer

23.08.2017: Nejra Sikalo has successfully passed his doctoral examination. Congratulations Nejra!

22.08.2017: Peter Janas has successfully passed his doctoral examination. Congratulations Peter!

17.08.2017: Publication accepted in Applied Optics: Mohri, K., Görs, S., Schöler, J., Rittler, A., Dreier, T., Schulz, C., Kempf, A. M. (2017), Instantaneous 3D- imaging of highly turbulent flames using Computed Tomography of Chemiluminescence (CTC)

25.07.2017: Minh Thuong Nguyen has successfully passed his doctoral examination. Congratulations Thuong!

02.06.2017: New bachelor and master projects are available. For more information, see Bachelor- & Master Projects.

28.04.2017: We have been awarded with a grant of 82 million core-hours to conduct massively parallel Direct Numerical Simulations and Large Eddy Simulations of turbulent premixed jet flames on SuperMUC at the Leibniz Supercomputing Centre. Project ID pr53fa. Coordinated by Dr.-Ing. Luis Cifuentes and Prof. Dr.-Ing. Andreas Kempf.

05.04.2017: Publication accepted in Physics of Fluids: „Vorticity budgets in premixed combusting turbulent flows at different Lewis numbers“ by Dopazo, Cifuentes, Chakraborty.

16.02.2017: New job vacancy as research associate on "Development and application of 3D tomographic techniques in engineering". For more information, see Open positions.

10.02.2017: Publication accepted for Combustion and Flame: „Flame resolved simulation of a turbulent premixed bluff-body burner experiment. Part II: A-priori and a-posteriori investigation of sub-grid scale wrinkling closures in the context of artificially thickened flame modeling“ by Proch, Domingo, Vervisch, Kempf

07.02.2017: Publication accepted for Combustion and Flame: „Flame resolved simulation of a turbulent premixed bluff-body burner experiment. Part I: Analysis of the reaction zone dynamics with tabulated chemistry“ by Proch, Domingo, Vervisch, Kempf

16.01.2017: Distinguished Paper Award for Martin Rieth: The manuscript "Flamelet LES modeling of coal combustion with detailed devolatilization by directly coupled CPD" by Rieth, Clements, Rabaçal, Proch, Stein and Kempf has been selected as the Distinguished Paper in the Solid Fuel Combustion colloquium for the 36th International Symposium on Combustion. Congratulations on this achievement!

 

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Visualization of instantaneous results from the 1.6 billion cell DNS of the Cambridge stratified burner. Left: Iso-q-criterion coloured by the axial velocity component. Right: Contour plot of equivalence ratio in the burner mid section, superimposed is an iso-surface for a progress variable value of C=0.5.tnisses, überlagert ist die Isofläche für einen Wert der dimensionslosen Fortschritts-Variable von C=0.5.