Simplified prediction models for acoustic installation effects of train-mounted equipment

Abstract

Acoustic models of railway vehicles in standstill and pass-by conditions can be used as part of a virtual certification process for new trains. For each piece of auxiliary equipment, the sound power measured on a test bench is combined with measured or predicted transfer functions. It is important, however, to allow for installation effects due to shielding by fairings or the train body. In the current work, fast-running analytical models are developed to determine these installation effects. The model for roof-mounted sources takes account of diffraction at the corner of the train body or fairing, using a barrier model. For equipment mounted under the train, the acoustic propagation from the sides of the source is based on free-field Green’s functions. The bottom surfaces are assumed to radiate initially into a cavity under the train, which is modelled with a simple diffuse field approach. The sound emitted from the gaps at the side of the cavity is then assumed to propagate to the receivers according to free-field Green’s functions. Results show good agreement with a 2.5D boundary element model and with measurements. Modelling uncertainty and parametric uncertainty are evaluated. The largest variability occurs due to the height and impedance of the ground, especially for a low receiver. This leads to standard deviations of up to 4 dB at low frequencies. For the roof-mounted sources, uncertainty over the location of the corner used in the equivalent barrier model can also lead to large standard deviations.

Keywords

Train noise / Auxiliary equipment / Acoustic installation effects / Virtual certification / Uncertainty

References

[1.] Commission Regulation (EU) (2014) No 1304/2014 of 26 November 2014 on the technical specification for interoperability relating to the subsystem ‘rolling stock—noise’ amending Decision 2008/232/EC and repealing Decision 2011/229/EU. Official Journal of the European Union: 421–437

[2.] International Organization for Standardization (2013) Acoustics—railway applications—measurements of noise emitted by railbound vehicles, ISO 3095:2013, Geneva

[3.] Galijatovic E, Eichlseder M, Heindl SF, et al.. Integrity of virtual testing for crash protection. Front Future Transp, 2022, 3,

[4.] Huizinga FTMJM, Van Ostaijen RAA, Van Oosten SA. A practical approach to virtual testing in automotive engineering. J Eng Des, 2002, 13(1): 33-47,

[5.] Dressler K, Speckert M, Bitsch G. Virtual durability test rigs for automotive engineering. Vehicle Syst Dyn, 2009, 47(4): 387-401,

[6.] You SS, Fricke D. Advances of virtual testing and hybrid simulation in automotive performance and durability evaluation. SAE Int J Mater Manuf, 2011, 4(1): 98-110,

[7.] Bezin Y, Funfschilling C, Kraft S, et al.. Virtual testing environment tools for railway vehicle certification. Proc IMechE Part F: J Rail Rapid Transit, 2015, 229(6): 755-769

[8.] Funfschilling C, Perrin G, Sebes M, et al.. Probabilistic simulation for the certification of railway vehicles. Proc IMechE Part F: J Rail Rapid Transit, 2015, 229(6): 770-781

[9.] Grappein E, Rueter A. Head pressure pulse in open air: Full assessment by computational fluid dynamics as a new standard. Proc IMechE Part F: J Rail Rapid Transit, 2015, 229(6): 570-580

[10.] Sima M, Eichinger S, Blanco A, et al.. Computational fluid dynamics simulation of rail vehicles in crosswind: application in norms and standards. Proc IMechE Part F: J Rail Rapid Transit, 2015, 229(6): 635-643

[11.] Bruni S, Bucca G, Carnevale M, et al.. Pantograph–catenary interaction: recent achievements and future research challenges. Int J Rail Transp, 2018, 6(2): 57-82,

[12.] Bongini E, Cordero R (2015) Virtual testing within the TSI noise: how to introduce numerical simulation into a certification process. In: Nielsen JCO et al. (Eds) Proceedings of 11th International Workshop on Railway Noise, Uddevalla, Notes on numerical fluid mechanics & multidisciplinary design 126:221–228

[13.] Bongini E (2015) A virtual certification process (validated). EU FP7 project ACOUTRAIN, grant agreement no. 284877, Deliverable D1.8

[14.] Frid A, Orrenius U, Kohrs T et al (2012) BRAINS—the concepts behind a quick and efficient tool for prediction of exterior and interior railway vehicle noise. In: Proc Acoustics 2012, Nantes, pp 23–27

[15.] Bistagnino A, Squicciarini G, Orrenius U et al (2015) Acoustical source modelling for rolling stock vehicles: the modeller’s point of view. In: EuroNoise 2015, Maastricht, pp 1991–1996

[16.] Thompson D, Squicciarini G (2014) Basic global prediction tool and user manual (final update of D4.2). EU FP7 project ACOUTRAIN, grant agreement no. 284877, Deliverable D4.7

[17.] International Organization for Standardization (1996) Determination of sound power levels of noise sources using sound intensity—part 2: Measurement by scanning. ISO 9614-2, Geneva

[18.] International Organization for Standardization (2010) Acoustics—determination of sound power levels of noise sources using sound pressure, ISO 3744, Geneva

[19.] Orrenius U, Feng L, Åbom M et al (2014) Rail vehicle source models within a virtual certification process. In: EuroNoise 2015, Maastricht, pp 2043–2048

[20.] Li H, Thompson D, Squicciarini G, et al.. Using a 2.5D boundary element model to predict the sound distribution on train external surfaces due to rolling noise. J Sound Vib, 2020, 486: 115599,

[21.] Pierce AD. Diffraction of sound around corners and over wide barriers. J Acoust Soc Am, 1974, 55(5): 941-955,

[22.] Attenborough K, Li KM, Horoshenkov K. . Predicting outdoor sound, 2007 London CRC Press

[23.] Haddon WJ, Pierce AD. Sound diffraction around screens and wedges for arbitrary point source locations. J Acoust Soc Am, 1981, 69(5): 1266-1276,

[24.] Mielenz KD. Computation of Fresnel integrals. J Res National Inst Stand Technol, 1997, 102(3): 363-365,

[25.] Delany ME, Bazley EN. Acoustical properties of fibrous absorbent materials. Appl Acoust, 1970, 3(2): 105-116,

[26.] Broadbent R, Thompson D, Jones CJC (2009) The acoustic properties of railway ballast. In: Euronoise 2009, Edinburgh

[27.] Thompson D. . Railway noise and vibration: mechanisms, modelling and means of control, 2009 Oxford Elsevier

[28.] Fahy F, Thompson D. . Fundamentals of sound and vibration, 2015 Boca Raton CRC Press,

[29.] Zhang X, Jeong H, Thompson D, et al.. The noise radiated by ballasted and slab tracks. Appl Acoust, 2019, 151: 193-205,

[30.] Bolin K, Rissmann M, Paillasseur S et al (2023) Measured source data for two selected sources based on sound intensity and on a 3D quantitative acoustic source imaging technique. Shift2Rail / H2020 project TRANSIT, grant agreement no. 881771, Deliverable D1.2

[31.] Cierco E, Bolin K, Rissmann M et al (2023) Validation of source and transmission models on a rail vehicle at stand-still. Shift2Rail/H2020 project TRANSIT, grant agreement no. 881771, Deliverable D1.5

Funding

Horizon 2020 Framework Programme(881771)