研究目的
To understand the effects of ullage (distance between burner rim and fuel surface) on the burning rate and flame structure of horizontal surfaces of poly methyl methacrylate (PMMA) and methyl methacrylate (MMA).
研究成果
The study demonstrates that ullage significantly affects burning rates and flame structures, with increased ullage leading to decreased burning rates due to reduced heat and oxygen transport. FDS simulations, despite some discrepancies, effectively capture gas-phase trends. The research provides fundamental data for fire dynamics and validates the use of FDS in such studies, suggesting improvements in pyrolysis modeling for better accuracy.
研究不足
The numerical model (FDS) shows deviations in temperature and species predictions near the fuel surface. The pyrolysis model may need fine-tuning, as burning rates are underpredicted. Experimental errors include reproducibility issues in species measurements (up to 20% for some species) and accuracy in temperature measurements (2.7-6%).
1：Experimental Design and Method Selection:
The study involves experimental and numerical investigations using a burner to orient fuel surfaces horizontally at specified ullages. Temperature and species fields are measured, and Fire Dynamics Simulator (FDS) is used for numerical simulations with infinite rate chemistry and sublimation or kinetic models for pyrolysis.
2：Sample Selection and Data Sources:
PMMA slabs (30 mm x 30 mm x 6 mm, density 1190 kg/m3) and MMA liquid are used as fuels. Data include temperature profiles, species concentrations, and mass loss rates from controlled experiments.
3：List of Experimental Equipment and Materials:
Equipment includes a fuel feed system, burner, Pt-Pt10%Rh thermocouples, microprobe, mass spectrometer (Hiden Analytical HPR60), AD converter (E14-140-M), electronic balance, and FDS software. Materials include PMMA, MMA, and calibration gases.
4：Experimental Procedures and Operational Workflow:
For MMA, fuel level is maintained at specific ullages; temperature and species measurements are taken using thermocouples and microprobe at various positions. For PMMA, slabs are ignited, and mass loss and temperature are recorded. Numerical simulations in FDS involve setting computational domains, mesh refinement, and boundary conditions.
5：Data Analysis Methods:
Temperature data are corrected for radiation using Collis and Williams formula; species concentrations are calibrated and averaged. FDS predictions are compared with experimental data for validation.
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