DETERMINATION OF CHARACTERISTICS AND SMOKE EXHAUSTERS PARAMETERS IN CONDITIONS OF INDEPENDED AND JOINT WORK WITH OTHER DEVICES BASED ON MATHEMATICAL MODEL
The principle of construction and examples of implementation of the developed mathematical model of the smoke exhaust system designed for operational use in case of fire for the elimination of gas pollution and lowering the temperature in the premises. Estimated target features of the installation are based on existing experience, namely: expected aerodynamic airway resistance: 80 Pa and volumetric air mixture flow rate of 3.3 m3/s. The specified characteristics and parameters necessary for the design, or modernization of existing axial fans, and their choice for three operating modes: independent work, joint work with the supply of finely divided water, joint work with the foam generating plant. Simplifications were used in the development of a mathematical model: scheme of the design of the axial fan, which does not involve the presence of a guiding apparatus; it is assumed that the flow in the operating cavity of the pump is axially symmetric; it is assumed that the thermodynamic process taking place in the pump cavity is isothermal; simplified formula of the lifting factor and drag coefficient of the grid is used on the basis of known table data. The mathematical model takes into account: the dimensions of the smoke exhaust system, the number and size of the blades, the angle of attack of the blade, the frequency of rotation, the amount of aerodynamic resistance of the airway, the density and the amount of supply of finely divided water or foam. The examples of the implementation of the developed mathematical model of the smoke exhaust system are illustrated in the form of diagrams of the location of the working points (volume flow of air mixture, m3/s, pressure, Pa; power of the engine of the smoke exhaust system, W) at operation of a smoke exhaust system in the conditions of the average airway for the three above-mentioned operating modes.