Effects of windbreak wall model lengths on aerodynamic characteristics of trains on different tracks in wind tunnel tests − a measurement strategy

Abstract

The length of a windbreak wall model is an important factor in a wind tunnel test. Aerodynamic characteristics of a vehicle on different tracks (windward line and leeward line) with windbreak wall models of different lengths were obtained by wind tunnel tests. The mean pressure and aerodynamic load coefficients (mean drag coefficient, side force coefficient, lift coefficient, and rolling moment coefficient around the lee rail) of the vehicle with the windbreak walls in different lengths were studied. The length of the windbreak wall had a greater effect on the aerodynamic characteristics of the vehicle on the windward line as compared to that on the leeward line. The length of the windbreak wall hardly affected the mean side force coefficient and rolling moment coefficient around the lee rail of the vehicle on the leeward line with the wall in the length over 21.67H (H is the height of the subgrade, including the rail plus the height of the train), whose change was no more than 3.2%. The fluctuations and frequency characteristics of the aerodynamic load coefficients in the length of 21.67H were the same as those with the windbreak wall reaching the wind tunnel wall. A new strategy for measuring the aerodynamic load coefficients of the vehicle with the windbreak wall was presented, which could accurately obtain their means and fluctuations. The maximum error was 1.3%.