Abstract

The sealing width of the mechanical seal of underwater vehicle propulsion shafting affects the mechanical sealing performance. In this study, the influence of sealing width on the mechanical properties of the mechanical seal was investigated with finite element method ( ANSYS ). The results show that the sealing width should be reduced as much as possible in order to lower the sealing surface temperature, and prevent the increase of nominal contact pressure and pcv value of the sealing surface; both sealing width of 31 mm and area ratio of 0.58 are more appropriate for the mechanical seal.

Intruduce

Sealing width is an important macroscopic geometric parameter of mechanical seal, and its value directly affects the sealing performance of sealing device. The friction heat generated by the sealing surface is proportional to the sealing width. The excessively wide sealing surface is easy to result in poor heat dissipation and higher temperature of the sealing surface, and even the vaporization phenomenon. If the sealing surface is too narrow, it will increase the specific pressure, deformation and contact area of the sealing surface, and aggravate friction, wear and leakage. With the development of ship modernization and enlargement, the higher requirements are put forward for the performance parameters of stern shaft sealing device so that the structural optimization of mechanical sealing ring has become a hot topic in the field of mechanical seal research.

Qin, Liu, Yan, Zhang, and Zhou (2013) optimized the dam seal in the aspect of temperature, stress, deformation etc. with finite element method to improve the sealing performance of the dam seal. The results show that the dam seal structure can reduce the highest temperature and stress of the dam sealing surface, and decrease the deformation and sealing gap of sealing surface.

Zhou (2017) deduced the mathematical expression of the sealing surface width of spherical mechanical seal with both theoretical and empirical formula, and discussed the influence rule of both inner diameter and outside diameter of the sealing rings on the contact pressure, temperature and the deformation of the sealing surface. Wei, Fang and Zhang (2020) analyzed the influencing factors of seal surface width on mechanical seal performance by simulation calculation. The calculation results indicate that the friction coefficient and leakage rate of sealing surface decrease with the increase of sealing surface width, and the largest elastic contact area is, the smallest plastic contact area is. He, Wang, Liu, Cheng, and Jiang (2018) investigated the influence of the mechanical seal surface width on the sealing performance under great diving depth and low speed, and gained the conclusion that the selected smaller seal width is beneficial to reduce the maximum temperature, axial stress, contact pressure and leakage rate. Cheng, Ge, and Yin (2002) studied the effects of rotate speed and sealing surface width on mechanical seal performance by experiments, and received the result that the narrow face width can significantly reduce the friction heat, but the sealing width has the negligible influence on friction coefficient under mixed-friction status. Choe, Lee, and Choe (2000) had successfully gained the optimal design values of outer and inner seal radii in the tested case and achieved the reduction of leakage by 38.4%. Tokunaga, Sugimura, and Yamamoto (2015) carried out a series of experiments to verify the sealing and lubricating performance of the surface structure for mechanical seals with the functions of the low-friction, low-leakage and pumping effect. Flitney and Nau (1992) used wear-rate and the temperature of seal body as alternatives for detecting the lubrication transition between full fluid film and mixed film conditions to demonstrate the performance capability of a particular mechanical seal design. Lu (2019) established a multi-objective optimization method considering dynamic fluid-type mechanical seal based on fluid-structure coupling model. The results show that the liquid film stiffness of the optimized model is 8% higher than the original model, and the leakage is 10% lower than the original model, and the results were verified by tests. Wang, Zhou, Yu (2017) studied a mechanical seal with elastic seal ring. The ring was used between seal ring and seal box and between seal ring and shaft sleeve to improve mechanical seal performance. Zhang (2016) optimized the sealing performance seal of mechanical seal. The results show that the mechanical seal can operate properly under the conditions including high pressure, low speed and spring pressure 0.1~ 0.2 MPa, and can decline temperature and leakage rate.

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