Dynamic analysis of the effect of nose length on train aerodynamic performance

Guang Chen; Xiao Bai Li; Zhen Liu; Dan Zhou; Zhe Wang; Xifeng Liang; Sinisa Krajnovic

doi:10.1016/j.jweia.2018.11.021

Dynamic analysis of the effect of nose length on train aerodynamic performance
Artikel i vetenskaplig tidskrift, 2019

The improved delayed detached eddy simulation (IDDES) was used to study the influence of the train’s nose
length on its aerodynamic performance. Both the time-averaged and instantaneous near-wake structures and the
associated distribution of slipstream velocity are compared for three nose lengths. As the nose length increases,
the mean and Std values of the drag and lift force are decreased. The shorter nose-length case results in a higher
slipstream velocity. In particular, at the TSI track-side position, the TSI value U_2δ
for the 5-m nose length case is 30% and 32% higher than the corresponding values for the 7.5-m and 10-m nose length cases, respectively. The
dynamical flow topology in the wake reveals that the flow structures of the 5-m nose length are different from
those of the other two cases in the tail streamline surface. As nose length increases, the longitudinal vortices are
weaker, and the angle and distance between the longitudinal vortices are smaller. The shear production from the P_xy
caused by the separation of the boundary layer at the lateral wall of the tail train is greater than that of the P_xz
caused by the separation of the boundary layer at the top and bottom of the tail train.