Aerodynamic noise radiating from the inter-coach windshield region of a high-speed train

Abstract

The aerodynamic noise has been the dominant factor of noise issues in high-speed train as the traveling speed increases. The inter-coach windshield region is considered as one of the main aerodynamic noise sources; however, the corresponding characteristics have not been well investigated. In this paper, a hybrid method is adopted to study the aerodynamic noise around the windshield region. The effectiveness of simulation methods is validated by a simple case of cavity noise. After that, the Reynolds-averaged Navier-Stokes simulation is used to obtain the characteristics of flow field around the windshield region, which determine the aerodynamic noise. Then the nonlinear acoustic solver approach is employed to acquire the near-field noise, while the Ffowcs-Williams/Hawking equation is solved for farfield acoustic propagation. The results indicate that the windshield region is approximately an open cavity filled with severe disturbance flow. According to the analysis of sound pressure distribution in the near-acoustic field, both sides of the windshield region appear symmetrical two-lobe shape with different directivities. The results of frequency spectrum analysis indicate that the aerodynamic noise inside inter-coach space is a typical broadband one from 100 Hz to 5k Hz, and most acoustic power is restricted in the low-medium frequency range (below 500 Hz). In addition, the acoustic power in the low frequency range (below 100 Hz) is closely related to the cavity resonance with the resonance peak frequency of 42 Hz. The overall sound pressure level at different speeds shows that the acoustic power grows approximately 5th power of the train speed. Two forms of outside-windshields are designed to reduce the noise around the windshield region, and the results show the full-windshield form is better in noise reduction, which apparently eliminates interior cavity noise of inter-coach space and lessens the overall sound pressure level on the sides of near-field by about 13 dB.

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

“…Liu et al 16 numerically verified that the full windshield generated less aerodynamic noise than the half windshield at the running speed of 350 km/h through large eddy simulation (LES) and Ffowc Williams-Hawkings (FW-H) acoustic analogy methods. 17 Dai et al 18 designed two types of outer windshield and confirmed through simulation that the full-windshield form was able to lessen the overall SPL on the sides of near-field by about 13 dB. Zhao et al 19 carried out a test in a 1:15 model wind tunnel, discovering that the turbulent fluctuating pressure at inter-coach space could be significantly reduced and the vibration and noise reduction could be achieved by means of full windshield treatment or setting spoilers (spoiler balls, spoiler pillars) upstream of the inter-coach space.…”

Nonlinear analysis and simulation of active hybrid aerodynamic and aerostatic bearing system

“…Currently, air lubricated bearings have replaced large number of traditional rolling component or liquid film lubricated bearings in instruments and equipment that require high precision axis positioning, high rotational speed, low friction, and have other special environmental requirements. 3 Studies on the performance of bearing and rotor (spindle) related dynamic characteristics of air lubricated spindle system show that the static and dynamic characteristics of high-speed rotor (spindle) directly affect the precision quality of the work piece. Therefore, when designing an spindle system, not only does the torsion or bending strength of the spindle must be calculated, but the static and dynamic stiffness should also be carefully designed.…”

“…Currently, air lubricated bearings have replaced large number of traditional rolling component or liquid film lubricated bearings in instruments and equipment that require high precision axis positioning, high rotational speed, low friction, and have other special environmental requirements. 3…”

Development of innovative methodologies to reduce railway rolling noise through Genetic Algorithm-based shape optimization techniques

“…Its radiated noise level is considered to have a dependency on the vehicle speed V of 60 log 10 V [4]. Besides, although relatively broadband, is dominated by tonal contributions and, most of its acoustic energy is concentrated in the low frequency range under 500 Hz and tonal contributions [4,193,194].…”