Numerical investigation into characteristics of far-field aerodynamic noise radiated by inter-coach space of high-speed maglev trains

Abstract

Self-sustain oscillation leads to aerodynamic noise at inter-coach space. It can be seen from existing literature that the aerodynamic noise at inter-coach space has already become an important branch in the domain of vibration and noise reduction of high-speed wheel-rail trains. However, to the best of our knowledge, approaches focusing on the identical problem that does exist in the windshield area of high-speed maglev train have not yet been published. In this paper, a computational model is established for the inter-coach space of high-speed maglev train running at the speed of 600 km·h−1. The model includes two half-mid-train with one outer full windshield connected. On the basis of Realizable k-ε model and Spalart-Allmaras DDES model, respectively, the steady and unsteady flow field are initially solved, and the pressure fluctuation on rigid surfaces, the vortex shedding process and the distribution of sound source power are then visualized to make clear the genesis mechanism of aerodynamic noise in the windshield area. With penetrable integration surfaces constructed, the far-field sound radiation is obtained from the Ffowc Williams-Hawkings (FW-H) equation, and the contribution rate of the quadrupole noise sources to the total aerodynamic noise is then calculated as a comparison to the previous conclusions that aerodynamic noise at inter-coach space of high-speed trains was mainly dipole. Of great significance, it is concluded in this paper that at the speed of 600 km·h−1, the quadrupole sound source contributes about 35.6% to the total sound energy in the far field, which is lower than the percentage using the entire train model at the same speed level but still cannot be ignored. The results in this paper are able to provide guidance for future researches on vibration and noise reduction of high-speed maglev train.

Numerical simulation and prediction of aerodynamic noise of high-speed trains

“…So the sound intensity generated by the point noise source can be considered as the sum of the sound intensity generated by the monopole source, dipole source and quadrupole source at the same point. According to equation (6) and (7), the sound intensity can be defined asWhere IM, ID, and IQ are the sound intensities of the three noise sources respectively.…”

“…2 Excessive aerodynamic noise will reduce passenger comfort, affect the life and work quality of people along the line, especially in hospitals, schools, residential areas and other noisesensitive areas, and even damage the hearing and nervous system of people inside and outside the car. [3][4][5][6] In China, aerodynamic noise pollution is considered to be one of the largest environmental pollution factors produced by high-speed railways to the society. According to the "14th Five-Year Plan of Action for Noise Pollution Prevention and Control", the equipment selection of urban rail vehicles and the construction of rail lines and roadbed structures should comply with the requirements for the prevention and control of noise pollution in urban rail transport.…”

Interior noise prediction of inter-coach space of high-speed maglev trains based on wavenumber decomposition on aerodynamic excitation

“…3,4 Conclusions are also drawn that inter-coach space is also a disturbance source and generates quadrupole noise to a non-negligible extent. 5 The Ffowc Williams-Hawkings (FW-H) acoustic analogy method 6 is generally used for far-field noise prediction, which efficiently separates near field turbulence flow and far field sound propagation located in the same physical medium and thus greatly saving computational resources compared to direct numerical simulation (DNS). The method is based on the assumption that there is no obstacle between the sound source and the receiver, but the mechanism and calculation of interior noise are far more complicated than such a case, which are rarely investigated in the domain of maglev transportation systems.…”