Studying of some dangerous factors of the initial stage of fire in residential premises with the use of modern technical means

Introduction. An experimental installation with data logging based on the Arduino platform was developed to implement the approach used in modeling the spread of fire hazards in small rooms. The values of the heat flow from the convective column of the combustion center in the initial stage of the fire for a residential building with a predominant cellulose load were determined using obtained device according to the zone model of the fire. Goals and objectives. The purpose of this work is to create a compact device that allows us to quickly assess the development of fire hazards over time at the initial stage of their occurrence and to hold experiments at objects comparable in size to real fragments of buildings and premises. Methods. An experiment with the use of the field test method of fire hazard testing and an assumption about the possibility of using the developed device in testing the dynamics of the spread of fire hazards in rooms with a cellulose fire load was conducted. It is based on the data about the zonal modeling of the spread of fire hazards using modern technical means. Results and discussions. Experimental studies seem to be a necessary part of the forecast of the spread of fire hazards in residential premises. Field fire tests, which refer to tests of fragments of buildings and structures that are close in size to real objects, are able most accurately convey the conditions that occur in apartments and private homes during the fire phase. The current level of development of microelectronics makes it possible to use hardware and software for a wide range of people, including those who do not have a special education. Device, developed and created by the authors, is based on the Arduino Mega 2560 platform. It is compact and portable. It allows quickly receive and record data from the experiment of modeling fire conditions in small rooms. The obtained results allows us to estimate the level of heat flow of the convective column from the ignited wood, which simulates the fire load in the room to the ceiling, as well as the average temperature of the gas medium and the heat loss coefficient in the ceiling. Conclusions. The using of the experimental device presented by the authors makes it possible to optimize the obtaining of individual characteristics of the dynamics of fire hazards at the initial stage of ignition. Keywords: fire hazards, zone fire model, heat flow, field fire test, arduino platform

Simulation Approach in Forecasting Radioactive Situation in Case of Forest Fires in Radioactive Contaminated Zones

Purpose: The accident at the Chernobyl NPP caused radioactive contamination of large areas, including forestry. For the last decades forest fires in the RF tend to increase and, more alarmingly, their burnt-out area significantly expands. So, the risk of large-scale forest fires in the area of radioactive contamination increases. Effectiveness of the measures for radiation protection of population and personnel involved in fire response is directly related to existence of valid methods of radiation situation prognostication. The work is aimed to develop a method of prognostication of radiation situation at forest fire in the area of radioactive contamination, taking into account random nature of atmospheric turbulence and a convective column over the body of fire, and to estimate validity of this method. Material and methods: Methods of simulation modeling of mass transfer processes in the atmosphere (method of Bird) based on the molecular-kinetic theory and gas-dynamic theory were used when developing the prognostication method. Results: The simulation model of formation, spreading and fall-out of radioactive cloud taking into account random nature of atmospheric turbulence and presence of a convective column over the body of fire has been developed; the method of prognostication of radiation situation at forest fire in the area of radioactive contamination has been developed and verified based on data of European experiment E1. The relative error of received values in the control points of radiation situation parameters based on data of experiment E1 did not exceed 0.25. Conclusion: Use of modified method of Bird allowed developing 3D dynamic model of spreading of radioactive impurity into atmosphere at convective rising by heated air flow from underlying surface. This model takes into account random nature of atmospheric turbulence and presence of a convective column over the body of fire which significantly increases accuracy of the method of radiation situation prognostication.

Modelling the chemistry and transport of bromoform within a sea breeze driven convective system during the SHIVA Campaign

We carry out a case study of the transport and chemistry of bromoform and its product gases (PGs) in a sea breeze driven convective episode on 19 November 2011 along the North West coast of Borneo during the "Stratospheric ozone: Halogen Impacts in a Varying Atmosphere" (SHIVA) campaign. We use ground based, ship, aircraft and balloon sonde observations made during the campaign, and a 3-D regional online transport and chemistry model capable of resolving clouds and convection explicitly that includes detailed bromine chemistry. The model simulates the temperature, wind speed, wind direction fairly well for the most part, and adequately captures the convection location, timing, and intensity. The simulated transport of bromoform from the boundary layer up to 12 km compares well to aircraft observations to support our conclusions. The model makes several predictions regarding bromine transport from the boundary layer to the level of convective detrainment (11 to 12 km). First, the majority of bromine undergoes this transport as bromoform. Second, insoluble organic bromine carbonyl species are transported to between 11 and 12 km, but only form a small proportion of the transported bromine. Third, soluble bromine species, which include bromine organic peroxides, hydrobromic acid (HBr), and hypobromous acid (HOBr), are washed out efficiently within the core of the convective column. Fourth, insoluble inorganic bromine species (principally Br2) are not washed out of the convective column, but are also not transported to the altitude of detrainment in large quantities. We expect that Br2 will make a larger relative contribution to the total vertical transport of bromine atoms in scenarios with higher CHBr3 mixing ratios in the boundary layer, which have been observed in other regions. Finally, given the highly detailed description of the chemistry, transport and washout of bromine compounds within our simulations, we make a series of recommendations about the physical and chemical processes that should be represented in 3-D chemical transport models (CTMs) and chemistry climate models (CCMs), which are the primary theoretical means of estimating the contribution made by CHBr3 and other very short-lived substances (VSLS) to the stratospheric bromine budget.

Firestorms

Quantitative criteria are sought for onset of firestorms, severe stationary (non-propagating) holocausts arising via merger of fires from multiple simultaneous ignitions in a heavily fuel-laden urban environment. Within an hour, surface-level radial inflow from all directions sustains a large-diameter convective column that eventually reaches altitude of about 10 km (e.g., Hamburg, Dresden, Hiroshima). As the firestorm achieves peak intensity (a couple of hours after the ignitions), inflow speeds are inferred to attain 25–50 m/s; typically 12 km2 are reduced to ashes, before winds relax to ambient levels in six-to-nine hours. Here the firestorm is interpreted to be a mesocyclone (rotating severe local storm). Even with exceedingly large heat release sustained over a concentrated area, in the presence of a very nearly autoconvectively unstable atmospheric stratification, onset of vigorous swirling on the scale of 2 hrs requires more than concentration of circulation associated with the rotation of the earth; rather, a preexisting, if weak, circulation appears necessary for firestorm cyclogenesis.