Comparative numerical investigation of flow-induced noise characteristics of high-speed trains using high-resolution compressible Large Eddy Simulation

The South Korean Ministry of Land, Infrastructure and Transport has developed a “Comprehensive Plan for 400km/h High-Speed Rail” aimed at enhancing the operational speed of the high-speed railways, currently running up to 300km/h. A short-term goal is to elevate the operating speed of high-speed trains to 370 km/h, up from 320 km/h. Because aerodynamic noise proportionally escalates with the 6th powers of the speed, aerodynamic noise becomes more significant at higher speeds. Consequently, there's a pressing need for design solutions that reduce aerodynamic noise in high-speed trains. This study involves an aeroacoustic analysis using real-scale models of the current model and the preliminary design targeting 370 kph operation. Each model's 8-car formation has been simplified to a 5- car setup. A challenge in predicting aerodynamic noise is the generation of detailed sound sources in the near field and precise noise propagation in the acoustic field. For that, a three-dimensional compressible Large Eddy Simulation technique is employed, utilizing high-resolution grids. This allows for concurrent computation of the external flow and acoustic fields for a real-scale, high-speed train in an open environment. The analysis comprehensively examines the aerodynamic and aeroacoustic properties of each train car, including the major contributors to aerodynamic noise in high-speed trains. The radiated noise is predicted using the Ffowcs Williams and Hawkings equation and is further examined in relation to vortex sound sources.