ON THE EVALUATION OF AIR FLOWS CAUSED BY A PISTON EFFECT IN SUBWAY TUNNELS

The results of numerical simulation of the piston effect in tunnels of a metro in combination with theoretical analysis are given. In the form of tables and graphs given the changes in these values depending on the speed of the train and the filling factor of the tunnel. The obtained results are compared with known analogous results from the literature sources. As a result of the comparison, there is a good agreement between of the main results presented in this paper and mentioned results. In this work established that the piston effect of the moving train in the subway tunnels is characterized by the existence of two phases that should be taken into consideration during estimation of the speed of air (circulation flows) ahead and rear of the train and the backflow in the annulus between a tunnel and moving train. In the first phase the piston effect has a non-stationary character and the process is stabilized in the second phase.