Abstract

One of the commissioning methods for building fire management systems is hot smoke test, in which liquid fuel is burnt to generate a buoyant plume mixed with artificial tracer smoke to model a fire smoke. The method is costly and often causes safety concerns. This thesis proposes an alternative method of "helium smoke test", in which pure helium is supplied to create the buoyant plume. Helium smoke test does not involve burning fuel and it is therefore safer than hot smoke test. This study developed a theoretical model of helium plume, conducted computational fluid dynamics (CFD) simulations to model smoke filling process for helium smoke test, validated the CFD model by the experiments in a full-size and a sub-scale building model, and then applied it to simulations of fire smoke propagations in an actual building and a scaled road tunnel.

Based on the theory of ideal fire smoke plume, the theoretical model was developed to determine the flow rate of helium necessary to achieve the same buoyancy effect as that of the corresponding hot smoke test. An original method was developed in the CFD model, fire dynamics simulator (FDS), to track the smoke layer height based on species concentrations. The FDS model was validated by measured data in a full-size atrium in the literature. To better validate the theoretical and the FDS models of helium smoke test, experiments were conducted in a 1:26.5 sub-scale building model. The smoke was illuminated by laser sheet optics and clear smoke layer height was then recorded. Helium concentrations were measured by a helium analyzer. It is found that helium smoke test can predict smoke layer heights as reasonably well as the corresponding hot smoke test with various fire sizes. The applications of helium smoke test are demonstrated by the simulations in a full-size building test facility and a sub-scale road tunnel at the Institute for Research in Construction of National Research Council Canada (NRC-IRC).