Numerical modelling of multi-phase aspects in fire-driven flows

Overview

The primary objective of Fire Safety Science and Engineering is to mitigate the adverse effects of fires. The development of reliable numerical tools allows to understand (and sometimes uncover) complex fire dynamics features, fostering therefore the development of science-driven design and firefighting strategies.

The research centered around multi-phase aspects focuses on a set of problems where the gas phase is interacting with the condensed phase, i.e., liquid or solid.

 

Multiphase flows

A particular interest is given to the following problems:

  • Liquid pool fires;
  • Water sprays and their interaction with flames, smoke and solid surfaces; and
  • Solid soot particles (formation, oxidation, transport and thermal radiation).  

 

Key elements of the modelling strategy

 

1) A fundamental understanding of the physics

A particular focus is put on:

  • Liquid heat-up and evaporation (in liquid pools and water sprays);
  • Heat transfer between a liquid and a solid surface;
  • The mechanisms of soot formation and oxidation;
  • Thermal radiation from soot.

 

2) A step-wise approach

In such approach, several aspects of the physics are decoupled in order to identify potential weaknesses in state-of-the-art modelling prior to proposing novel models. Here are several examples:

  • In the application of liquid pool fires, liquid heat-up and evaporation are first addressed in non-reacting conditions (i.e., no flaming) before considering the coupling with the flame (gas phase).
  • In the application of water sprays, the canonical configuration of a single droplet is studied prior (or in addition) to a full spray.
  • Soot modelling is first assessed in laminar flames prior to turbulent flames where there is Turbulence Chemistry Interaction (TCI) and Turbulence Radiation Interaction (TRI) (collaboration with Prof. Bart Merci).

 

3)  A strong collaboration with experimentalists. The purpose is to (1) design, in close collaboration with experimentalists, experiments that are tailor-made for the modelling strategy described above and (2) have access to high-quality and well-documented experimental data.

 

4)  Accuracy Vs Computational time.  Fire-driven flows are very complex because of the strong interaction amongst several aspects of the physics (e.g., heat transfer, combustion) and chemistry and the large domains over which a fire develops. One of the objectives of the proposed modelling is not to (systematically) resort to ‘brute force’ (i.e., heavy computational resources) but to develop models that are suitable for ‘practical fire dynamics simulations’.   

Contact

Prof. Tarek Beji

Collaboration within the FSSE group

Research projects

Research projects Multi-phase aspects in fire