Preparatory Experiments for Studying Smoke Dynamics

The first laboratory experiments of the fire simulation group at JSC have started with a preparatory setup. Supported by ZEA-1 and IEK-6 at Forschungszentrum Jülich, the experiments aim to study the spread of heat and smoke in a reduced scale geometry. Similar scale reduction (1:20) is often used in fire safety science to evaluate smoke exhaust systems and to dispense with costly real-scale experiments. As ventilation in complex buildings is crucial for smoke and fire dynamics, it also plays a central role in the experiment. The setup permits a large number of parameters and therefore the experimental implementation is based on orthogonal parameter space sampling.

As the expected flow will be turbulent, single point measurements of the flow properties are not sufficient. The PIV (particle image velocimetry) technique applied allows the flow to be measured in a plane. The basic principle is to seed the measurement volume with tracer particles and then illuminate the diagnostic area with a laser. A camera setup records the positions of the illuminated particles. This information is used to compute the particle displacements and therefore the gas flow that advects the tracer particles.

The preparatory setup currently in operation is used to characterize the energy source, an electrically heated block of copper, and to evaluate the diagnostics in a simple setup: a glass cube with the energy source on a stand at the bottom. Using PIV, the global flows in the cube and in the vicinity of the stand are captured. Additionally, the heterogeneous surface temperature of the heated block is monitored with a thermal camera.

Although the experimental results are of intrinsic interest, the data will be used to validate existing CFD codes and software developed in-house. Additionally, surrogate models based on the experimental and simulation data will be compared.
(Contact: Dr. Lukas Arnold, l.arnold@fz-juelich.de)

from JSC News No. 227, 12 December 2014