Comparative study of aeroacoustic performance of 1/8 and 1/1 pantographs coupled with cavity

Abstract

The technology of pantograph sinking in the cavity is generally adopted in the new generation of high-speed trains in China for aerodynamic noise reduction in this region. This study takes a high-speed train with a 4-car formation and a pantograph as the research object and compares the aerodynamic acoustic performance of two scale models, 1/8 and 1/1, using large eddy simulation and Ffowcs Williams–Hawkings integral equation. It is found that there is no direct scale similarity between their aeroacoustic performance. The 1/1 model airflow is separated at the leading edge of the panhead and reattached to the panhead, and its vortex shedding Strouhal number (St) is 0.17. However, the 1/8 model airflow is separated directly at the leading edge of the panhead, and its St is 0.13. The cavity’s vortex shedding frequency is in agreement with that calculated by the Rooster empirical formula. The two scale models exhibit some similar characteristics in distribution of sound source energy, but the energy distribution of the 1/8 model is more concentrated in the middle and lower regions. The contribution rates of their middle and lower regions to the radiated noise in the two models are 27.3% and 87.2%, respectively. The peak frequencies of the radiated noise from the 1/1 model are 307 and 571 Hz. The 307 Hz is consistent with the frequency of panhead vortex shedding, and the 571 Hz is more likely to be the result of the superposition of various components. In contrast, the peak frequencies of the radiated noise from the 1/8 scale model are 280 and 1970 Hz. The 280 Hz comes from the shear layer oscillation between the cavity and the bottom frame, and the 1970 Hz is close to the frequency at which the panhead vortex sheds. This shows that the scaled model results need to be corrected before applying to the full-scale model.

Keywords

Pantograph cavity coupling / Aerodynamic noise / Scale effect / Large eddy simulation

References

[1] Tian HQ (2007) Train aerodynamics. China Railway Press, Beijing, pp 1–18 (in Chinese)

[2] Lauterbach A, Ehrenfried K, Loose S, et al. . Microphone array wind tunnel measurements of Reynolds number effects in high-speed train aeroacoustics. Int J Aeroacoust. 2012, 11(3–4): 411-446

[3] Zhang Y, Zhang J, Li T, et al. . Investigation of the aeroacoustic behavior and aerodynamic noise of a high-speed train pantograph. Sci China Technol Sci. 2017, 60(4): 561-575

[4] Tan XM, Yang ZG, Tan XM, et al. . Vortex structures and aeroacoustic performance of the flow field of the pantograph. J Sound Vib. 2018, 432: 17-32

[5] Liu JL, Yu MG, Tian AQ, et al. . Study on the aerodynamic noise characteristics of the pantograph of the high-speed train. J Mech Eng. 2018, 54(4): 231-237 in Chinese)

[6] Sun X, Xiao H. Numerical modeling and investigation on aerodynamic noise characteristics of pantographs in high-speed trains. Complexity. 2018, 2018: 6932596

[7] Latorre Iglesias E, Thompson DJ, Smith MG. Component-based model to predict aerodynamic noise from high-speed train pantographs. J Sound Vib. 2017, 394: 280-305

[8] Ihme J. Rail vehicle technology. 2022, Wiesbaden, Springer

[9] Masson E, Paradot N, Allain E. The numerical prediction of the aerodynamic noise of the TGV POS high-speed train power car. Noise and Vibration Mitigation for Rail Transportation Systems. 2012, Tokyo, Springer: 437444

[10] Zhu JY, Hu ZW, Thompson DJ. The flow and flow-induced noise behaviour of a simplified high-speed train bogie in the cavity with and without a fairing. Proc Inst Mech Eng Part F J Rail Rapid Transit. 2018, 232(3): 759-773

[11] Norberg C. Fluctuating lift on a circular cylinder: review and new measurements. J Fluids Struct. 2003, 17(1): 57-96

[12] Knisely CW. Strouhal numbers of rectangular cylinders at incidence: a review and new data. J Fluids Struct. 1990, 4(4): 371-393

[13] Okajima A. Strouhal numbers of rectangular cylinders. J Fluid Mech. 1982, 123: 379-398

[14] Bai H, Alam MM. Dependence of square cylinder wake on Reynolds number. Phys Fluids. 2018, 30(1))

[15] Tracy MB, Plentovich EB (2014) Characterization of cavity flow fields using pressure data obtained in the Langley 0.3-meter transonic cryogenic tunnel. Available via NASA Langley Technical Report Server. https://ntrs.nasa.gov/citations/19930013687. Accessed 10 Sept 2023

[16] Plentovich E, Stallings JR, Tracy MB (2003) Experimental cavity pressure measurements at subsonic and transonic speeds static-pressure results. Available via NASA Langley Technical Report Server. https://doi.org/10.5555/887492. Accessed 15 Oct 2023

[17] Park HM, Dhir CS, Oh DK et al (2005) Filterbank-based blind signal separation with estimated sound direction. In: 2005 IEEE international symposium on circuits and systems (ISCAS), Kobe, Japan, 2005, vol 6. IEEE, New York, 5874–5877

[18] Hunt JCR, Wray AA, Moin P (1988) Eddies, streams and convergence zones in turbulent flows. In: Studying turbulence using numerical simulation databases, 2. Proceedings of the 1988 Summer Program. Ames Research Center, pp 193–208

[19] Strouhal V. Ueber eine besondere Art der Tonerregung. Ann Phys. 2006, 241: 216-251

[20] Rossiter JE (1966) Wind-tunnel experiments on the flow over rectangular cavities at subsonic and transonic speeds. R&M 3438. Available via AERADE. https://naca.central.cranfield.ac.uk/handle/1826.2/4020. Accessed 15 Aug 2023

Funding

National Natural Science Foundation of China(52272363)