Aerodynamic Effects as a Maglev Train Passes Through a Noise Barrier
Artikel i vetenskaplig tidskrift, 2020
The aerodynamic performance of a maglev (magnetic levitation) train (MT) passing through a two-sided noise barrier was simulated by the improved delayed detached eddy simulations. The influence of the presence of noise barrier on both sides on the flow field around the MT and the pressure field in the noise barrier area are analyzed. The effect of changes of the noise barrier height and the centre of track (COT) distance parameter on its flow field were also studied. Numerical simulation results were verified by the moving model test. The results show that the noise barrier increases the pressure in the area around a train. The maximum pressure changes most as the tip of the head of the MT passes through the measuring point. The maximum positive and negative pressure amplitudes of the head wave on the inner wall surface of the noise barrier are increased by 83.5% and 58.4% compared to those the same height position measurement point in open air. On the inner wall of the barrier, the fluctuation of the pressure decreases with the increased height of the probe, which is opposite to the trend on the outer wall. Inside the noise barrier, the wind velocity in the x-direction is greater than that in open air when the tip of the nose and tail of the car passes. But the velocity in the y-direction when the tip of the head and tail cars passes is limited, and two speed peaks appear in the horizontal direction train induced wind. The higher the noise barrier, the higher pressure of the same height measurement point in the noise barrier area. Due to the passage of the train, the top of the noise barrier has a certain vorticity at the position of the head car and the tail car. Changing the height of the noise barrier changes how the vortex structure at the tail of the train develops. Moving the noise barrier further from the COT causes the fluctuations at the pressure measurement point inside the noise barrier to diminish meaning the pressure enhancement effect caused by the height of the noise barrier also diminishes.