Description
The Kan-etsu Tunnel is the longest mountain road tunnel in Japan. It is ventilated longitudinally by axial fans in two shafts and by axial fans in precipitator ducts. Until this year, all fans have been operated at constant speed with variable flow rates achieved by adjusting blade angles. In recent years, however, snow melting agent convected into the tunnel by vehicle movements has damaged the blade adjustment systems and necessitated repairs. A long-term solution was hypothesized in which the fans would operate at a variable speed with constant blade angle. using inverter control. A test program with the prototype followed and, when it yielded positive results, a decision was taken to proceed with full-scale implementation. However, further damage prevented the implementation of this solution in full, and an alternative involving supplementary jet fans was devised with all fans – axial and jet – operating at variable speed controlled by inverters. The paper describes the design, validation, and aerodynamic simulations of the system and compares its performance with the original configuration with axial fans operated at constant speed with variable blade angle.
