CROSS-COMPARISON OF MEASUREMENT TECHNIQUES FOR THE DETERMINATION OF TRAIN-INDUCED AERODYNAMIC LOADS ON THE TRACKBED

aerodynamic load on trackbed Abstract: Within the research cooperation “Aerodynamics in Open Air ” (AOA)- as part of the French-German DEUFRAKO programme- a track-side measurement campaign has been carried out in Italy focusing on the loads imposed by passing trains on the trackbed. The test site on the high-speed line Roma/Firenze included both segments of ballasted track and slab track. The time series recorded from the passage of about 30 regular trains per track of the ETR 500 family have been postprocessed according to a general approach which is proprosed as a standard for future campaigns. Several types of averages, including ensemble mean, “train” average, and phase averaging have been computed and analyzed. It has been demonstrated that classical pressure probes as well as high-frequency ultra-sonic anemometers are suitable devices for the assessment of the average air speed above the trackbed. However, care has to be taken if details in the nose region of the leading vehicle come in to focus where local flow reversal occurs. Pressure probe signals are spoiled by the occur-rence of resonances in the tubing. Low-pass filtering is a suitable way to arrive at physically meaningful signals. Fluctuations up to a frequency of 100Hz could be resolved, allowing to distinguish coherent and stochastic contributions. With respect to the mean axial flow speed different probe types deviate by up to 5%.