Author(s): Fast Dennis, Kirchner Karl-Richard, Kohrs Torsten, Vallespin Alberto, Sapena Joan, Guiral Garcia Ainara, Martner Otto
Within the European rail initiative Shift2Rail, funded by the European Union, the FINE1 project aims at improving energy efficiency and state-of-the-art noise modelling and control for railway systems. For high energy efficiency, it is vital to reduce the mass of the trainsets. With this mass reduction the challenge to achieve high sound transmission losses of the carbody structures increases. To meet the rising demands for acoustic comfort inside the trains while fulfilling the more stringent mass targets, the need for accurate interior noise prediction methods is growing. Current industrial interior noise prediction methods rely on a mixture of empirical, analytical, statistical and numerical approaches.\nOne important aspect of the interior noise prediction is the sound distribution around the carbody for source excitations from different geometrical positions, e.g. the sound pressure field on the carbody structure generated by a sound source in the underframe. The paper presents the results of simulations of the pressure field around the carbody for either artificial sources or real operation in free field and tunnel. The practicality and validity of using different calculation approaches like BEM, ray tracing, SEA and standardized outdoor sound propagation is investigated in combination with selected validation test results. Due to the large variety of parameters involved, further work is needed to deduce processes for general application in free field and tunnel. By investigating the influence of a coarse and more detailed geometry some recommendations for future modelling are given. The resulting generalized transfer functions shall form a basis for refining the actual interior noise prediction tools used in the railway industry.
Name: Dr Torsten Kohrs