Архив статей журнала
Foam solution discharge is always accompanied by changes in the operating pressure due to different pressure losses along the pipeline in automatic foam extinguishing systems. Changes in the operating pressure affect the process of a liquid jet fragmentation into droplets and the formation of foam films. Therefore, to increase the accuracy of calculations when designing automatic foam extinguishing systems, it is worthwhile to evaluate the main characteristics of the foam in terms of fire extinguishing efficiency, in particular, its expansion. For this purpose, the generalization of the experimental data using the theory of similarity and taking into consideration the hydrodynamic features of the deflector type sprinkler operation and the properties of foam solution was carried out to develop a novel simplified mathematical model. This model allows to predict the foam expansion depending on the geometric parameters of the sprinkler elements and the empirical coefficient, which takes into account the peculiarities of the chemical composition of the foam concentrate. This new model predictions of foam expansion show good agreement with the experimentally measured foam expansion. The average error in foam expansion was less than 9 %.
The paper is devoted to the issues of predicting the temperature distribution in asphalt concrete layers in different periods of the year. Mechanical parameters of asphalt concrete strongly depend on its temperature. The reliability of the temperature dependence used for temperature prediction directly determines the reliability of calculation methods for motorway pavements design. At the same time, it should be noted that many existing models describe the temperature distribution along the depth of the asphalt concrete layer package with a rather large degree of error and are not calibrated for the conditions of the Russian Federation. Methods. The approach proposed by the authors is based on the study of the actual temperature distribution in asphalt concrete pavements by analyzing data from a set of measuring sensors installed at different depths of the asphalt concrete pavement package. The actual temperature distribution was monitored during the annual cycle from March 2023 to April 2024. Results. To approximate the results obtained, a dependence describing the sinusoidal nature of temperature variation on the surface and in the asphalt concrete layers was modified. Modification of the dependence was carried out by introducing an additional empirical parameter characterizing the dependence of the change in the absolute temperature value on the depth. The accuracy of the modified dependence is confirmed by the root mean square error (RMSE) value of up to 10 %. Conclusions. The model modified in the paper can be used at the stage of design and operation of motorways when calculating the temperature conditions of asphalt concrete layers.