• Journal of KSNVE
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• v.10 no.4
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• pp.629-635
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• 2000

Wheel /rail interaction has been known as a major source of railway noise. In this paper, a low noise wheel structure is developed and its effect on noise reduction is investigated. The developed low noise wheel employees a rubber material inserted into a steel rim or mounted on the wheel surface. Since the low noise wheel has low stiffness and high damping ratio compared to a solid wheel, the measurement results show that it reduces the rolling and squeal noise. It turns out that the proposed wheel could reduce interior noise level by 4∼5dB(A) and vehicle vibration level by 7∼10 dB. Although the proposed structure seems to be promising in noise reduction of railway vehicles, the low noise wheel is to be verified in endurance and cost effect.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2163-2172
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• 2008

The noise to be considered as the most important in railway systems is the noise generated from the wheel/rail interaction. Such noise can be divided into three categories; that is, the rolling noise, the squeal noise and the wheel howling noise. Especially in metro systems, this type of noise has been considered seriously in recent years, and the diversified studies on the mechanism and solutions of such noise are in progress by many railways and researching bodies. In this study, a specially designed wheel absorber is installed in the wheel, and FEM analysis and laboratory tests are executed for the two cases, i.e. with wheel absorber and without wheel absorber, to check the effect of the wheel absorber in noise reduction. For the FEM analysis, the frequency response functions for respective cases are compared. And, for the laboratory test, following four cases are tested and compared; that is, i) with wheel only, ii) installation of ring damper only, iii) installation of damping material and cover, iv) installation of complete absorber system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.851-856
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• 2012

Automotive turbochargers have become common in gasoline engines as well as diesel engines. They are excellent devices to effectively increase fuel efficiency and power of the engines, but they unfortunately cause several noise problems. The noises are classified into mechanical noises induced from movement of a rotating shaft and aerodynamic noises by air flow in turbochargers. The mechanical noises are whine and howling noises, and the aerodynamic noises are BPF (blade-passing frequency), pulsation, surge, some special frequency noises. These noises are bothering passengers because their levels are higher or their frequencies are clearly separated from engine or vehicle noises. The noise investigated in this paper is a BPF noise induced by compressor wheels, whose frequency is the multiplication of the number of compressor wheel blades and its rotational speed. The noise is strongly dependent upon the geometry of wheels and the number of blades. This study tried to apply a groove close to the inlet side of compressor wheels in order to reduce the BPF noise. The groove has successfully reduced the noise of narrow band frequency of a turbocharger. It shows that the groove could reduce the wide band frequency noise, the compressor BPF noise with a best shape of the groove.