Effect of air chambers on the compression wave propagating along a high-speed railway tunnel
Tóm tắt
An array of air chambers embedded on the tunnel track is numerically investigated for different configurations. The air chambers act as an in-tunnel countermeasure to alleviate non-linear steepening of compression waves during propagation process thereby mitigating emission of high amplitude micro-pressure waves (MPWs) from the exit portal. The air chambers are designed to entrap the incoming flow and induce damping behavior so as to reduce wave steepening in tunnels. Initially, qualititative comparisons are made between Helmholtz resonator and damping type air chambers. Thereafter, the quantitative assessment of the compression wave properties are checked in detail. From results, over damped air chamber shows 60 % reduction in peak over pressure for weak compression wave whereas the Helmholtz resonator and critically damped shows 35 % and 22 %, respectively. Similarly, due to the presence of over damped air chamber, 17 % reduction in maximum pressure gradient is noticed while critically damped shows close to 10 % reduction.
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