Development of tunnel compression wave generator with multiple small solenoid valves

The micro-pressure wave (MPW) phenomenon caused by a high-speed train entering a tunnel consists of three stages: generation of the tunnel compression wave upon train entry, propagation of the tunnel compression wave through the tunnel, and emission of the MPW outward. Model experiments using train launcher facilities (TLFs) are effective for analyzing MPWs. However, the use of those facilities to study the latter two stages, i.e., the compression wave propagation and MPW emission, is hindered by two problems: high costs required for facility operation and construction, and low data productivity. Compression wave generators can potentially provide reasonable experiments. In this study, a new, simple facility was developed for the simulation of tunnel compression waves. The proposed generator consists of small solenoid valves, a pressure chamber, compressor, power supply system, and tunnel model. The performance analyses indicate that the compression waves generated by the designed facility effectively simulate tunnel compression waves generated by train entry. The pressure rise and wavelength of the compression wave are controlled by adjusting the chamber pressure and the voltage applied to the valves. The generator is expected to provide sufficient data to develop measures against MPWs in the propagation and emission stages as it reduces the required time by over 60% compared to that required by TLFs for each generation of the compression waves.