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  2. Research
  3. Scientific Departments
  4. Process Engineering
  5. Multiphase Flow, Heat and Mass Transfer
Mann mit Labor Kittel nimmt Proben aus einer moderen Maschine

In the department "Multiphase Flow, Heat and Mass Transfer" the research activities are concentrated on processes for the production, handling and conditioning of disperse phases (e.g. powders, particles or droplets) in liquid or solid form. In particular, the analysis of the interaction processes at the phase interfaces of particles with their fluid environment, which are characterized by multi-phase impulse, heat and mass transfer processes, is in the foreground.

Essential applications of the investigations in this area are processes with spray and jet flows from the production and handling of metallic and ceramic powders and thermal process technology.

Basic investigations in multiphase flow systems and practice-oriented questions of application in e.g. multiphase cooling processes in the context of heat treatment of metals are treated.

For the scientific objectives of the department "Multiphase Flow", laser-optical measuring methods of fluid and particle technology are developed and applied as tools in combination with numerical simulation calculations and modelling. Based on this, measures for process design and optimization are derived and verified.

Analysis of multiphase flow systems

  • Laser light-section visualization (LLS)
  • Schlieren optics
  • High Speed Videography (HSP)
  • Concentration measurement
  • Measurement of particle size, particle velocity and particle temperature distributions

 

Atomization and spray characterization

  • Analysis of liquid decay
  • Spray characterization
  • Spray cooling, spray coating, spray compaction

 

Powder analyses

  • Particle size and shape
  • Flowability

 

Modelling and simulation of multiphase systems

  • Multiphase flows
  • Fluid atomization and spray propagation
  • Quenching and cooling processes
  • Evaporation, condensation and solidification processes

 

Test facilities for particle-loaded multiphase flows are used for:

  •  Atomization of fluids, melts and solutions, suspensions and emulsions
  • Transport of particles
  • Dispersion, separation and conditioning of particles
  • Laser Doppler and Phase Doppler Anemometry (LDA / PDA)
  • Particle Image Velocimetry (PIV)
  • High Speed Particle Pyrometry (HSP)
  • diffraction spectrometry (BSM)
  • Hot-wire anemometry (CTA)
  • Visualization: Short term videography, schlieren optics systems, laser light section system

Detection of micro processes and structures during the dispersion of fluids, emulsions, suspensions and melts

  • Dispersion and disintegration processes during atomization
  • Emulsification processes of complex rheological fluids
  • Microfluidics and emulsification of fluids and melts in porous structures and membranes
  • Inline quality control of emulsions and cooling lubricants

 

Generation of powders and semi-finished products from mineral, metallic and polymer melts

 

  • Concepts for atomization units for energy-efficient processes and adapted product properties of powders in the micro- and nanometer range
  • Development of thermal and kinetic boundary conditions for the derivation of adapted process control strategies
  • Powder production in spray processes, process technology of spray compacting

 

Process analysis and optimization in thermal process technology

  • Analysis of flow and heat transfer conditions on complex components in gas and liquid quenching processes
  • Development of spatially and temporally controlled heat transfer scenarios
  • Cooling and quenching with spray and jet systems in liquids and gases
  • Derivation of strategies to avoid or compensate for component distortion in the manufacturing process
  • Energy efficiency in thermal process technology

 

Development of numerical models for the description of multiphase flows (M-CFD Multiphase Computational Fluid Dynamics)

  • Models for the description of topology changes in multiphase flows (atomization, drop decay and coalescence, ...)
  • Lattice Boltzmann method for the analysis of multiphase flows
  • Coupling of thermal models and phase field modelling
  • Modelling of the evaporation process (flow boiling)
  • Modelling for spatially and temporally resolved dispersion flows (Sharp Interface Model)
  • Dynamic Flow Sheet Simulation of particulate processes (solid process engineering)
  • OpenFOAM extensions for M-CFD
  • Coupling of CFD and PBM (population balances)
  • Turbulent Combustion Modelling
  • Particles from the gas phase, modelling and simulation
  • Modelling of ultrasonic applications

Projects of Multiphase Flow, Heat and Mass Transfer

VerA distortion compensation in aluminum die casting process chains

The aim of the VerA project is to develop a method of compensating for process-induced residual stresses in aluminum die casting during production. The complete process chain from casting to heat treatment is considered.

The motivation of the project is the economical production of large-area, of thin-walled die-cast integral components that meet the lightweight construction requirements of the automotive industry. Currently, cost-intensive measures such as straightening operations are necessary to compensate for distortion. In the process chain under consideration, from casting to heat treatment, locally controlled quenching is used to influence distortion and internal stresses during heat treatment. Quenching is performed by adaptive spray field systems. When adapting the spray field, component-specific data from process monitoring are used so that warpage can be compensated for by optimum local cooling rates.

This project was funded by the German Federation of Industrial Research Associations (AiF).

Processing: IWT departments of Process Engineering and Lightweight Materials

Funding: BMWi-AiF

Duration: 01.04.2022 - 30.09.2024

Contact:
M.Sc. Lisa Husemann
Tel.: +49421 218 51325
E-Mail: husemann@iwt-bremen.de

Dilyan Kamenov
Tel.: +49421 218 51231
E-Mail: d.kamenov(at)iwt.uni-bremen.de

 

Grafik, die verschiedene Phasen eines Fertigungsprozesses zeigt, darunter Druckguss, Abkühlen (Wasser), Stanzen, Lösungsglühen, Abkühlen (Luft), Warmauslagern und Spannungsarmglühen. Jede Phase ist mit einer farbcodierten Temperaturverteilung dargestellt.
Distortion development over the die casting process chain (Project DIMTAL, AiF 15687 N, [Schimanski, K., von Hehl, A. Thin-walled and warpage-free die cast components in automotive engineering - A contradiction? Casting of chassis and body components, VDI Special Day, Magdeburg, 07 February 2013.])
Influence of nozzle field arrangements consisting of jet and full-cone nozzles on the intensive cooling of moving thick plates

In this project, the intensive cooling of hot sheets with water from single nozzles and nozzle arrays was investigated.

For this purpose, experimental investigations with full-jet and spray nozzles were carried out at the University of Magdeburg (Research Unit 1) and numerical modeling and simulations were performed at the Leibniz Institute for Materials Engineering IWT Bremen (Research Unit 2).

The subject of the experimental investigations were single full jet and full cone nozzles as well as nozzle arrays consisting of 9 to 10 full jet nozzles, 2 full cone nozzles, 2 flat jet nozzles and combinations of full and flat jet nozzles. During the cooling process, the temperatures of the cooled sheets on the back side were measured with an infrared camera. An essential result of the experimental investigations is the concrete proof of the influence of technical parameters such as initial temperature, jet velocity, sheet velocity, metal type, etc. on the DNB or Leidenfrost temperature, the heat transfer and the progress of the wetting front.

The numerical simulation is based on a modified Euler-Euler multiphase model. With the developed 3D simulation model, the entire cooling process with all associated boiling phases can be calculated. Based on the simulation results, process states such as the Leidenfrost region, the heat transfer coefficient (HTC), the local heat flux or the temperature gradient at the impinging surface, which cannot be directly detected in experiments, can be analyzed in detail. The model allows the calculation of different nozzle types, nozzle arrangements and three-dimensional nozzle fields as well as the analysis of the cooling of a moving plate (thick sheet).

There is sufficient agreement in the results from experiment and simulation. In particular, experiment and simulation show the same tendencies depending on the change of technical parameters of cooling.

With the results of the project, characteristic values are available which are suitable for the design and optimization of cooling or quenching systems of moving plates. The possibilities of a transfer to industry are given.

The final report of the project can be obtained from the Forschungskuratorium Maschinenbau (FKM) e. V. (postal address: Lyoner Str. 18, 60528 Frankfurt am Main, e-mail: info@fkm-net.de).

Processing: Otto von Guericke University Magdeburg, Institute of Fluid Mechanics and Thermodynamics, Leibniz Institute for Materials Engineering, IWT Bremen.

Duration: 01.05.2018 - 31.10.2021

Funding: BMWi-AiF

The IGF project 20107 BG/1 of the Research Association Forschungskuratorium Maschinenbau e. V. - FKM, Lyoner Straße 18, 60528 Frankfurt am Main was funded by the Federal Ministry of Economic Affairs and Climate Action via the AiF within the framework of the program for the promotion of joint industrial research (IGF) based on a resolution of the German Bundestag.

Contact:
Prof. Dr.-Ing. habil. Udo Fritsching
Tel.: +49421 218 51230
E-Mail: ufri(at)iwt.uni-bremen.de

M.Sc. Nithin Mohan Narayan
Tel.: +49421 218 64509
E-Mail: n.narayan(at)iwt.uni-bremen.de

 

Quenching with polymer solution: Flow field analysis in industrial quenching tanks

The heat treatment of large metal components is typically performed by immersion in a quenching solution. In this process, the steel workpiece’s hardening depends on rapid and homogeneous cooling.

Aqueous polymer solutions offer distinct advantages over traditional oil or water quenching, including improved ecological impact and adjustable quenching performance. However, their use can lead to explosive rewetting, which destabilizes the component batch and can damage the quenching tank. Accordingly, the aim of the project is to evaluate the flow in industrial tanks to determine whether they provide a homogeneous flow inside them. The analysis combines experimental velocity measurements with a numerical model. Recommendations for the fluidic design of such plants can then be derived and the flow influence on the process can be understood.

Cooperation: Leibniz-IWT VT/WT, Universität Bremen
Funding: BMWK-AiF/IGF-Vorhaben Nr. 22025 N

 

 

Contact: 
M.Sc. Matheus Rover Barbieri 
Tel.: +49 421 218 64530 
E-Mail: m.barbieri@iwt.uni-bremen.de

Quantification of the mixing zone and Intensification of the mixing process of two nanoparticle producing flames for the design of hetero contacts

Double-flame spray pyrolysis (DFSP) enables the production of nanoparticles with customised properties for industrial applications. The aim of this sub-project in SPP 2289 is to quantify the mixing zone of the two spray flames and to achieve an intensification of the mixing zone.

To this end, the process of nanoparticle formation in the spray flame and the sintering process in OpenFOAM will be modelled. The complexity and extremely short time and length scales of the process are challenging to allow for a deeper analysis and understanding of the process. Particular attention is paid to the flow regimes present in the mixing zone. A geometric parameter variation is used to change the mixing zone in order to analyse it in detail. The results show a clear influence of the geometric configuration on the mixing zone.

Cooperation: Universität Bremen
Funding: DFG (SPP 2289)

 

 

Contact:
M.Sc. Tobias Tabeling
Tel.: +49 421 218 51212
E-Mail: t.tabeling@iwt.uni-bremen.de

Fully-coupled simulation of the coolant/lubricant fluid dynamics and the cutting process in vibration-assisted drilling

Vibration-assisted drilling, with its additional axial movement, is investigated with minimum quantity lubrication (MQL). The combination of both technologies improves the drilling process, but also increases the number of process and control variables to be coordinated.

In 2024, the previously developed coupled vibration-assisted drilling model was further developed and used to investigate the wetting of the machining zone and the gas flow dependent chip transport.

Cooperation: Leibniz-IWT VT/FT
Funding: DFG (SPP 2231 FluSimPro)

 

 

Contact:
Teresa Tonn
Tel.: +49 421 218 51235
E-Mail: t.tonn@iwt.uni-bremen.de

TEMPUS – High-temperature gas atomization of metallic materials

The objective of the project is to reduce gas consumption in the atomization of metal melts by utilizing gas temperatures around 800 °C in order to reduce consumption costs and the CO2 footprint.

To this end, the atomization technology previously used for metal melts will be extended to atomize with gas at up to 1000 °C to investigate the influence of high gas temperatures on the process, operational safety, gas consumption, transferability to different alloys and powder quality with regard to application in additive manufacturing. The AiF project is supported by producers and users of metallic powders as well as manufacturers of metal powder plants, heat exchangers and technical gases.

 

 

Funding: AiF-Forschungsvereinigung Wärmebehandlung und Werkstofftechnik (22851 N)

 

 

Contact:
M.Sc. Aline Weicht 
Tel.: +49 421 218 51223 
E-Mail: a.weicht@iwt.uni-bremen.de

SPP 1980 subproject: analysis and control of atomization and mixing areas in spray flames

Flame spray pyrolysis (FSP) is a powerful technique for the synthesis of nanoparticles in the gas phase and is based on precursor atomization, droplet evaporation, combustion, particle nucleation and particle growth.

The complexity and short time and length scales of the process are challenging to allow a deep understanding of the process. The aim of the project is to deepen the fundamentals of the spray formation and dynamics that determine reaction condition using sophisticated laser diagnostics.

 

 

Funding: DFG (SPP 1980)

Integral coupled simulation of the fluid dynamics of the cooling lubricant and the cutting process during vibration-assisted drilling – ViBohr

This project aims to develop an in-depth understanding of the dynamics, resulting effects, and interactions of minimal quantity lubrication (MQL) in vibration-assisted drilling by numerically modelling the interactions between flow dynamics and chip formation.

 

Cooperation: Leibniz-IWT FT/VT
Funding: DFG (SPP 2231)

Kontakt:
M.Sc. Lukas Schumski 
Tel.: +49 421 218 51152 
E-Mail: schumski@iwt-bremen.de