In the article, it is proposed to use a numerical method based on the approach of S.K. Godunov to simulate boiling in a pipeline. The paper presents a statement of the real problem of modeling a water hammer, considering possible boiling of the transported liquid on a real object — an oil pipeline. When solving the problem, two variants of flow modeling when closing the valve installed at the end of the pipeline were carried out. In the first Наука и техника 14 Безопасность Труда в Промышленности • Occupational Safety in Industry • № 11'2020 • www.safety.ru case, the possibility of liquid boiling was not considered. In the second case, this opportunity was considered. The performed numerical simulation showed that in the pipeline in emergency situations, liquid columns can be formed, separated by the cavitation zones and oscillating in different phases, respectively, at the collapse of the cavitation zones, which serve as a kind of pressure dampers, the collisions of liquid columns occur, which can lead, depending on the ratio of velocities, to hydraulic shocks that occur not on the valves, but on the linear part of the pipeline (local hydraulic shocks). The waves from these collapses, interacting with each other, create the new pressure peaks that do not coincide with the pattern of simple wave circulation, which are predicted in the simulations that do not consider possible liquid boiling. As a resul t, the pressures reached in the pipeline during fluid hammer is significantly different from what it would be in the absence of boiling. When boiling is considered, the maximum reached pressures are 40 % higher. Moreover, this excess is repeated. The detailed analysis of the pressure profile in the pipeline is given in the article. Based on the results of solving this problem, it is concluded that when modeling pre–emergency and emergency situations in the pipeline, it is necessary to consider the process of possible liquid boiling, since sometimes, as in the presented case, the values of the pressure surges can be higher than the values of the pressure surges in the liquid without considering boiling, which increases the likelihood of emergency depressurization.
Simulation of ground bearing pressure profile under hydraulic crane outrigger mats for the verification of 16-point combined loading
