CALCULATED ASSESSMENT OF THE DEPENDENCE OF THE INTENSITY OF WIND INFLUENCE ON THE POSSIBILITY OF FIRE SPREADING TO NEARBY BUILDINGS

Anna Borysova; Oleksandr Nuianzin; Serhii Khriapak

Anna Borysova Institute of Public Administration and Research in Civil Protection
Oleksandr Nuianzin Cherkasy Institute of Fire Safety named after Chornobyl Heroes of National University of Civil Protection of Ukraine
Serhii Khriapak Institute of Public Administration and Research in Civil Protection

Keywords: adjacent building objects, mathematical model, fire model, temperature, critical surface heat flux density

Abstract

A model of heat exchange processes between the source of thermal radiation and the studied samples was developed by using methods of steady-state and non-steady-state thermal conductivity according to the methods of gas dynamics. The dependence of the change in temperature and the critical surface density of the heat flow on the speed of the air flow on the samples and the distance from the source of heat action was determined. The conducted research and generated data tables can be used in the future for the development of an improved simplified method of forecasting the thermal impact of fire on adjacent construction objects, taking into account wind influence.

With the help of the FDS software complex, a model of heat exchange during a fire was created step by step. The dependence of the temperature change on the air flow rate on the samples and the distance from the source of thermal action was determined. The resulting dependence can be further determined by a correction factor that will take certain criteria into account. This coefficient will be expedient to use when substantiating fire-fighting distances between buildings and structures due to the mathematical model of heat exchange between objects during a fire using gas dynamics methods, as well as when substantiating the algorithm for creating a mathematical model of FDS heat and mass transfer during the burning of a class A fire.

Based on the revealed regularities, a table of safe distances was constructed depending on the heat-generating capacity of the fire load, wind speed, and duration of exposure to determine the correction factor for wind exposure. The methodological basis for the calculation justification of the minimum safe fire distances has been expanded by creating structural schemes-methods that together make up a hierarchical structure and are the theoretical basis for creating the corresponding regulatory basis. It was established that the wind speed during the assessment of the spread of fire to neighboring buildings can be taken into account by introducing a correction factor into the formula for calculating the safe fire distance between buildings.