A compression wave generated when a high-speed train emerges from the exit
portal of a tunnel. causes an impulsive noise called micro-pressure wave. T
here are various countermeasures to reduce the micro-pressure wave, the mos
t effective one being the proper design of the nose shape of the train. In
the present study, we adopted a new method for the prediction of sonic boom
noise, considering the effect of the nose shape on the resultant noise. Th
e Euler equation is first solved. after which the linear Kirchhoff formulat
ion is used for the prediction of farfield acoustics from the flow-field da
ta.
Experimental investigation is also carried out on the pressure fluctuations
in the tunnel and the micro-pressure wave with parameters such as train sp
eed, blockage ratio, nose shape of train and air-shafts. The computational
prediction and experimentally measured data, compared in this paper, show a
good agreement with each other. The results shows that several countermeas
ures could be used for the efficient reduction of the micro-pressure wave.
(C) 2001 Academic Press.