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.

06.09.2019 Publication accepted in Chemical Enginnering Science

A collaborative work as a combination of the simulation, experiment, and theoretical quantum chemical calculation resulted in a paper accepted in chemical engineering science journal. In this study,a chemical reaction mechanism is developed for the oxidation of Tetramethylsilane (TMS) as a precursor in a lean low-pressure (p ≈ 30 mbar) H2/O2/Ar flame using species mole fractions, obtained from molecular-beam mass spectrometry (MBMS) measurements in a matrix-supported flat flame doped with 600 ppm TMS as a starting point.

Chem. Eng. Sci. 115209 (2019)

23.08.2019 New publication on the SpraySyn burner

Collaboration between several IVG members resulted in a paper recently published in the Review of Scientific Instruments journal. The SpraySyn burner is presented which is studied within the priority program SPP1980. The burner is a piloted spray burner used for nano particle synthesis. Experimental and numerical results are presented which serve the characterisation of the flame.

Rev. Sci. Instrum 90, 085108 (2019)

 

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.

11.04.2019 Publication accepted in Fuel

Transient auto-igniting jet flame with a domain lenght of over 40 nozzle-diameters is simulated using sophisticated combustion models.

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

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

Events at IVG

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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.