Characterization of Fire Induced Flow Transport Along Ceilings Using Salt-Water Modeling

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Yao, Xiaobo
Marshall, André W.
This research provides a detailed analysis of turbulent mixing and heat transfer in canonical fire plume configurations by using a quantitative salt-water modeling technique. The methodology of quantitative salt-water modeling builds on the analogy between salt-water flow and fire induced flow, which has been successfully used in the qualitative analysis of fires. Non-intrusive laser diagnostics, Planar Laser Induced Fluorescence (PLIF) and Laser Doppler Velocimetry (LDV), have been implemented to measure the dimensionless density difference and velocity in salt-water plumes. In the implementation of the PLIF technique, the salt-water concentration is measured through tracking a fluorescent dye tracer within the entire spatial domain of a planar section of the salt-water flow, which is diluted at the same rate as the salt water. The quantitative salt-water modeling technique has been validated by comparing it with real fire experiments and theoretical data. The scaling laws are also proved by varying the initial source strength or ceiling height in the impinging plume configuration. The detailed salt-water measurements provide insight into of the wall interactions and laminarization effects in the impinging plume configuration. Additionally, highly resolved measurements provide mean profiles and turbulent statistics which will be useful for validating and developing sub-grid scale models in Computational Fluid Dynamics (CFD) codes. Furthermore, an engineering heat transfer model is developed to predict the convective ceiling heat transfer from impinging plumes using the quantitative salt-water modeling technique along with an adiabatic wall modeling concept. The successful application of the adiabatic wall heat transfer model illustrates a well controlled method for studying the heat transfer issues in more complex fire induced flow configurations by using the quantitative salt-water modeling technique.