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Research

Our research focuses on various aspects of combustion modelling. Traditional research areas are the modelling of turbulent combustion processes, pollutant formation, analysis of flame structure and combustion regimes, ignition and chemical kinetics. New areas are multiphase reactive flows and high temperature synthesis of nanoparticles. Our current research is theoretical and numerical only.

Current projects:

Combustion Modelling

Flash Boiling Processes

Contact Person: Dirk Dietzel
For steering a space craft in the outer space small thrusters are used, where fuel combustion gives the necessary propulsion. The oxygen, essential for any combustion process, is supplied to the combustion chamber in liquid form. Due to the low pressure vacuum conditions within rocket engines, the liquid is rapidly depressurized below its saturation pressure causing high rates of bubble nucleation and evaporation and a fast disintegration of the liquid jet into a disperse spray containing small sized droplets occurs. ... [more]

LES-MMC Modelling

Contact Person: Gregor Neuber
Large Eddy Simulation (LES) is increasingly used to predict complex flow and mixing phenomena. LES resolves the largest flow structures, but small-scale processes like particle formation require closure. We model homogeneous nucleation and condensation of dibutyl phthalate (DBP) droplets in a turbulent jet using LES in combination with a probability density function/Monte Carlo method. ... [more]

Stratified Flames

Contact Person: Carmen Straub
The global demand for clean and low cost sources of energy continues to increase. This demand creates a need for fuel efficient and low pollutant emissions engines. Numerical simulations play an important role in efforts that seek to address these challenges. To enable the use of simulations in combustion, we develop a computational approach to predict combustion processes. ... [more]

Dense Sprays

Contact Person: Bosen Wang
Spray combustion is usually treated in the Euler-Lagrange context where Euler equations are solved for the continuous (carrier) phase and the dispersed phase is modelled by discrete (Lagrange) particles. Some common combustion models for LES, such as flamelet and CMC, rely on the existence of a characteristic variable such as mixture fraction and the strong correlation of the reacting species on this variable. ... [more]

Pulverised Coal Particle

Contact Person: Giovanni Luigi Tufano and Dr. Oliver T. Stein
Coal represents the world's major source of primary energy for generating electrical base load power. Despite the recent encouraging rise of alternative and renewable energy sources the current status is not expected to change significantly over the next few decades. However, pulverised coal combustion (PCC) is inherently polluting in nature and the aim of ... [more]

Coal Combustion

Contact Person: Dr. Oliver T. Stein and Gregor Olenik
Coal is presently one of the most important energy sources and pulverised coal combustion (PCC) is the dominant form of base load electricity production. To gain higher burner efficiencies and reduce pollutant formation detailed investigations of the combustion process are required. Optical measurement techniques are often difficult to apply in coal flames, and therefore numerical methods are essential for the analysis of the coal flame structure and pollutant formation. ... [more]

Large-EddySimulation

Contact Person: Papakorn Siwaborworn and Salvador Navarro-Martinez
State-of-the-art computational fluid dynamics will use Large-Eddy Simulation (LES) to solve the flow and mixing fields where the large, unsteady, energy containing structures (eddies) are computed explicitly and the small, more universal dissipative scales are modelled. LES can provide more accurate predictions of the flow and mixing fields than conventional RANS based methods, in particular for the complex geometries of many engineering applications. ... [more]

Multiple Mapping Conditioning

Contact Person: Matthew Clearly, Konstantina Vogiatzaki and Andrew P. Wandel
Multiple Mapping Conditioning (MMC) provides a generalized framework for the application of mapping functions to turbulent reacting flows. The MMC model solves for the conditional expectations of all scalars conditioned on a set of reference variables. It overcomes some of the closure problems associated with CMC methods and implicitly provides the joint PDF of the conditioning scalars and the conditioned dissipation rates. Deterministic and stochastic implementations of MMC exist. ... [more]

Spray Combustion

Contact Person: Satoshi Ukai
Liquid spray fuel combustion systems have been used for a wide range of applications. However, the numerical simulation of liquid spray combustion still remains a challenging task due to its multi-scale nature associated with turbulence, chemical reactions and particle interactions. The large eddy simulation (LES) method has been developed to reduce the computational load by modeling the unresolved small scale turbulence, and it has been validated in various types of flow. ... [more]

Particlesynthesis

Agglomeration Of Nanoparticles

Contact Person: Gizem Inci and Milena Smiljanic
The agglomeration of nanoparticles is of growing importance in industrial production processes of nanomaterials, in which the structure of the agglomerates defines essential product characteristics. Therefore monitoring and control of agglomerates and their structure is of major importance and subject of many research studies. Simulation and modelling of agglomerate formation in real flows is a typical multi-scale problem with respect to the relative size of nanoparticles and the larger scales of the flow, and most studies focus either on individual collisions of particles neglecting the larger scales or resolve the large scale flow motion and model agglomeration by semi-empirical closures. ... [more]

Flame Synthesis of Nanoparticles

Contact Person: Son Vo
Large eddy simulation (LES) has become a useful approach for modelling turbulent reacting flows in which large scales are resolved and small scales are modeled. The main challenge for the modelling of turbulent reacting flows using LES is the closure of the filtered reaction rate. This is due to the non-linear denpendence on the local, instantaneous species composition and temperature. ... [more]

Modelling of Particle Synthesis

Contact Person: Niko Seubert
The better understanding of condensation and growth of nano-scale droplets from fluids may be of major importance for the control of phenomena such as anthropogenic aerosols. A well known example of man made aerosol pollution are the condensation trails of airplane engines. Experiments may not reveal the full nature of condensation and nucleation processes due to the wide range of scales involved and numerical simulations are needed to support our efforts in understanding all physical processes that affect nano-droplet formation. ... [more]

Past projects:

Chemical Kinetics

Contact Person: Fabie Cerru
The inclusion of chemical kinetics into calculation methods for turbulent flows typically requires simplified chemistry and systematically reduced mechanisms. This project analyses the oxidation and reduction paths of sulphur with potential applications in high temperature mixing layers associated with plumes from aircraft. ... [more]

Combustion in IC Engines

Contact Person: Francesco Bottone, Anthony Jefferies and Kian Mehravaran
Novel diesel combustion concepts breaking the traditional NOx vs. PM trade-off of classic diffusion controlled combustion require better understanding of the complex turbulence-chemistry interactions that strongly influence the formation and destruction of pollutants. The work within this project extends the existing CFD methodology for engine simulation to accurately account for (i) mixing of fuel and oxidizer, especially due to large-scale motion, (ii) turbulence-chemistry interactions and (iii) cycle-to-cycle variations that cannot be predicted by current state-of-the-art three-dimensional Reynolds-averaged simulations (RAS). ... [more]

Conditional Moment Closure Modelling

Contact Person: Prof. Andreas Kronenburg
The development of the conditional moment closure method and its application to turbulent reacting flows is a central theme of the Turbulent Combustion Modelling Group. Current research focuses on double conditioning, second moment closures and conditionally filtered moments. ... [mehr]

Extinction and Ignition

Contact Person: Markus Kostka
Singly conditioned moments do not satisfactorily describe combustion processes in the presence of extinction and re-ignition. A new theoretical model (an extension of the singly conditional moment closure method) is being developed to account for large temperature fluctuations due to local extinction. Possible applications are the computation of ignition processes in IC engines or the flame stabilization mechanisms in gas turbines. ... [more]

SAS Processes

Contact Person: Jung Jin Choi
Supercritical antisolvent (SAS) processes have become a promising method for the production of micro- and nano-sized particles. The relatively easy control of particle size and morphology allows the production of particles with desired properties and makes the SAS process attractive for various industrial applications that can be found in the pharmaceutical/nutriceutical industries, in polymer particle engineering and solid propellant manufacturing. ... [more]

Subgrid-scale Modelling

Contact Person: Andreas Papoutsakis
Large-Eddy Simulation solves for spatially filtered quantities and all scales smaller than the spatial filters need be modelled. This project aims at the development of better models for sub-grid scale dissipation, variance and their conditional expectations. Models are derived with the aid of Direct Numerical Simulation that necessitate the use of High Performance Computing facilities. ... [more]

Workshops:

In close collaboration with national and international research groups ITV organises the workshop series “Measurement and Simulation of Coal and Biomass Conversion” (CBC). Further information on the workshop can be found here.