Predicting Smoke Concentration in the Ceiling Jet

摘要

Predicting smoke detector response to a growing fire requires calculating thetime dependent evolution of the smoke concentration in the ceiling jet. Typically, the temperature rather than the smoke concentration has been used to predict smoke detector response due to the availability of correlations which give ceiling jet temperature and the assumption that the smoke concentration can be realted to ceiling jet temperature. Using temperature to predict smoke detector activation ignores differences in the production of smoke by burning materials that may completely invalidate a temperature/smoke prediction correlation. In this paper, an algebraic correlation for smoke concentration in the ceiling jet will be developed. The analysis will be restricted to fires that produce turbulent plumes and can be represented by axisymmetric point sources. Once the smoke concentration is predicted, the activation times for smoke detectors can be calculated using a model for smoke detector activation.