Effects of experimental bogie fairings on the aerodynamic drag of the ETR 500 high speed train *

The well streamlined design of the last generation European high speed trains has already taken in account the necessity to minimise drag. A further development to reduce drag for such trains is to cover the bogie areas with smooth and streamlined surfaces. To quantify the aerodynamic effects of bogie fairings on drag a research project joining DB, SNCF and FS, with the co-operation of the train manufacturer Ansaldobreda, has been undertaken on the new multi-voltage ETR 500 high speed train. The research programme has included both wind tunnel tests and full-scale tests. Reduced scale tests were performed by a 1:7.5 model of ETR 500 with a locomotive and two trailers. Measurements carried out on the first trailer without fairing and with different fairing geometries have shown that optimised fairings can decrease drag of about 20% while retrofittable fairings allow a reduction higher than 10%. After this results FS ordered to Ansaldobreda the design and the construction of a complete set of bogie fairings to be assembled on all the bogies of the ETR 500. The effects of the bogie fairings were tested in 95 test-runs undertaken by FS and DB in October 2000 on the high speed line linking Roma to Firenze. Full-scale tests were carried out on an ETR 500 normally used in operations, made of 2 locomotives and 8 trailer cars, both with and without bogie fairings. A reduced configuration with only 3 cars was also tested in order to investigate the effects of train length on drag. Drag measurements, undertaken by the coasting method, were carried out within a test section of straight track with small slope, where speed up to 300 km/h can be reached under test conditions. The tests covered a speed range about from 100 km/h to 300 km/h. The full scale tests of the ETR 500 have shown a strong effect of the bogie fairings on the aerodynamic drag. The measured drag of the ETR 500 with fairings is approximately 10 % lower than the drag of standard configuration without fairings. This drag reduction could be further increased if the fairing design was aimed for the aerodynamic optimisation and not only for the retrofitting on the existing bogies. The success of this research project proved that the optimisation of the train surface in the bogie area can strongly affect the aerodynamic drag of the high speed trains.