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CFD modelling

A powerful and affordable tool


​Computational Fluid Dynamics (CFD) is a powerful and affordable tool to enable a deep understanding of and the design of various industrial flow processes such as combustion in boiler furnaces, chemical reactors and other mixing processes. With CFD, we acquire detailed information of local process conditions, and we can speed up process and product development. Modelling helps to find solutions for the growing demands for new and more efficient processes with low emissions.

CFD was utilised to support Fortum Power Solutions’ design of:

  • A new air staging principle for bubbling fluidised bed boilers ensuring low emissions and good boiler performance.
  • a new low-NOx gas burner for lean gas combustion, optimising its performance.


Multiphase CFD was used to analyse and understand the flow dynamics in the flotation equipment of Outotec (Finland) Oy.

Long experience of modelling complicated flow processes

We have over 30 years experience of the application and development of CFD modelling tools for combustion and industrial multiphase flows. We have combined in an innovative way various modelling approaches with CFD, e.g. FEM for fluid-structure interaction, multiblock modelling, cellular automata, large reaction mechanisms, a unique and fast method for time-averaged simulation of fluidised bed hydrodynamics.

Our current research include the utilisation of CFD to e.g.

  • Boiler furnace retrofits to meet IED emission limits and allow safe and flexible (load, fuel mixtures) operation with high performance
  • Study fast pyrolysis reactors for bio oil production
  • Analyse flotation equipments
  • Thermal hydraulics related to the safety of nuclear reactors 

Approaches to solve customer’s tasks

We use the CFD programs ANSYS Fluent and OpenFOAM. We have a close cooperation with several companies and universities, notably with boiler manufacturers, power companies and the process industry. In many cases the client benefits most when we bring together VTT’s process know-how, experimental work at VTT’s pilots and measurements from client’s equipment and the utilization of various modelling methods.

Our know-how and wide experience of modelling and simulating demanding physico-chemical processes is also utilized in other flow processes. VTT is on its way to extending the application of CFD modelling to e.g. the brazing and welding of metals. 

​CFD modelling yields lean gas burner


Customer: Fortum Power Solutions

Challenge: Develop a new low NOx gas burner for lean gas combustion

Solution: VTT used Computational Fluid Dynamics (CFD) modelling to support the design of the burner, optimising its performance

Key benefits:

  • Creation of a more efficient burner design
  • Burner operated reliably, just as simulations predicted