Time-variant characteristic under the piston wind on subway tunnel billboard

The study of the time-variant characteristic on billboards caused by the piston wind deals with the issue of the billboards falling out in the subway tunnel. A method of a full-scale physical model and the corresponding numerical model are established, and the dynamic meshing deformation to simulate the metro runs in the tunnel was used, where good agreement between the simulation result and the experimental result was achieved proving the model to be correct. On this basis, the flow field in the actual subway tunnel is simulated, and the wind pressure time-variant characteristic on the billboards is analyzed. The results demonstrate that the static pressure on the billboard surface goes through a series of changes: "uniform distribution - left and right gradient - up and down gradient - uniform distribution". The billboard's upper right corner of the driving direction is subjected to the largest pressure and hence most vulnerable to damage. This method can provide guidance to the installation and maintenance of billboards in practical engineering applications.