Fire modeling of pitched roof combustion

Purpose. To develop a physico-mathematical model and to determine the regularities of thermal and gas-dynamic interaction during the combustion of pitched roofs made of combustible building materials using computational fluid and gas dynamics methods. The processes of convective and radiative heat flux formation are to be considered in order to further refine the geometric parameters of the radiating surface and to assess the thermal impact on adjacent buildings and structures. Methods. Numerical simulation of pitched roof combustion in ANSYS Fluent 2022 R2. The calculations were made using the SST k–ω turbulence model, a turbulent combustion model incorporating the eddy dissipation model, the discrete ordinates method for radiative heat transfer, a pyrolysis model for roofing materials, and a single-step soot formation model. Boundary conditions were specified based on previously conducted experimental studies. Findings. Spatial-temporal distributions of temperature fields and heat flux intensities during pitched roof combustion were obtained. Based on the results of numerical simulations performed in the ANSYS Fluent software environment, it was established that during roof combustion, at a distance of 1 m horizontally and 1 m vertically from the gable and the roof slope, the temperature values range from 530 to 590 K, while the heat flux density varies from 4.5 to 8.0 kW/m². The obtained data are in good agreement with the results of experimental studies, confirming the validity of the model. The processes of pyrolysis, turbulent combustion, radiative heat transfer, and soot formation in the modeling of pitched roof combustion were comprehensively investigated. Application field of research. Determination of fire separation distances between buildings with roofs made of combustible materials. The obtained data can be used to improve engineering methodologies and fire safety regulatory documents and are also of practical interest to engineering organizations, design institutes, personnel of the MES, research and educational institutions.