Scale study on aeroacoustic characteristics of high-speed train bogie region
The 1꞉8 scaled simplified bogie model at train speed of 400 km/h was simulated employing large eddy simulation(LES)and finite element acoustics.The flow disturbance characteristics and aerodynamic sound characteristics of the same model at 1꞉4,1꞉8,1꞉16 and 1꞉25 scale were simulated and compared.The results show that there is a pronounced coupling effect between the leading shear flow within the bogie region and the bogie structure and cavity,revealing two distinctive cyclic feedback disturbance modes denoted as L1 and L2.Additionally,secondary disturbances among the bogie structure are observed,intensifying the instability of the shear flow and serving as the primary modes of aerodynamic sound in the region.The simulations at 1꞉4,1꞉8,1꞉16 and 1꞉25 scale sizes reveal significant alterations in flow disturbance characteristics,especially in the L2 feedback mode,as the scale varies.With the decrease of scale,fluctuations in surface pressure and acoustic source energy shift towards higher frequencies.The source energy exhibited an initial decrease followed by an increase,within a range of 2 dB.Furthermore,the proportion of source energy originating from the structure and rear wheel pair increases.When the scale ratio are 1꞉4,1꞉8,1꞉16,and 1꞉25,the frequency-corrected standard point average sound pressure levels are recorded as 105.5,103.9,104.3,and 105.1 dB(A),respectively,presenting a range of 1.6 dB.Anticipatedly,this discrepancy is expected to be amplified for a full-scale model.
high-speed trainbogiescale effectsaerodynamic noiseLESacoustic finite element
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