The stern tube seal of a ship often generates abnormal vibration and noise due to the friction excitation between the static ring and the dynamic ring. Through shipboard testing, it was found that this abnormal vibration appears in the form of the torsional vibration natural frequency of the static ring and its harmonics in the vibration spectrum. In order to reveal the cause of this phenomenon, this paper establishes a nonlinear torsional vibration analysis model for the stern tube seal considering the contact-friction effect between the static ring and the dynamic ring. The influence of parameters such as shaft system rotational speed, friction coefficient, Ω spring preload, Ω spring torsional stiffness, and structural damping ratio on the vibration of the stern tube seal was studied using multiscale method and numerical simulation. The results show that when the equivalent damping ratio induced by the friction excitation is smaller than the structural damping ratio, the static ring of the stern tube seal will exhibit friction-induced self-excited vibration, that is, the occurrence of the torsional vibration natural frequency of the static ring and its harmonics in the vibration spectrum. Increasing the Ω spring preload, and increasing the difference in static and dynamic friction coefficients between the static ring and the dynamic ring, or reducing the rotational speed of the shaft system and the torsional stiffness of the Ω spring will make the static ring more susceptible to friction-induced self-excited vibration. Increasing the structural damping ratio can effectively suppress the friction-induced self-excited vibration of the static ring. Finally, this paper provides a critical formula for the occurrence of friction-induced self-excited vibration in the static ring. This research has important guiding significance for the design and maintenance of stern tube seals.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |