Design And Performance Research Of Composite Static Ring For Stern Shaft Seal

The stern shaft seal plays an important role in the ship’s propulsion system,directly affects the ship’s normal navigation,and prevents contamination of nearby waters.However,due to the rotation,vibration and axial motion of the stern shaft,as well as its direct contact with the sea water,the working environment of sealing device is extremely harsh,and local contact zones of high pressure are easily formed.At the same time,due to the frictional heat generated by the mutual rotation of the sealing ring,as well as the stirring heat between the fluid at the end face,the local high temperature of the sealing ring at the end face leads to thermal deformation and thermal stress.In the complex thermal-mechanical coupling process,the stern shaft seal is easy to failure,which is manifested by wear on the end face of static ring and excessive leakage.Therefore,it is of great theoretical significance and practical application value to design anti-friction and wear-resistant static rings and study the thermal-mechanical coupling characteristics of stern shaft seal.Around the resin matrix composite,two composite structures of winding and braiding are designed,and the performance of composite material is predicted for different parameters.The fracture behavior and failure laws of two structures under compressive load are discussed.The static ring is made of two kinds of designed materials,and compared with the static ring made of Thordon material,a new type of stern shaft sealing device is proposed.The effect of sealing pairs at different speeds and static ring materials is investigated.At the same time,sealing tests are carried out on the stern shaft sealing bench,and the wear mechanism of composite material is discussed.The results show that:1.The end face’s temperature of Thordon/alloy sealing pair is the smallest.The opening force of sealing pair increases linearly from 2.56 k N to 5.66 k N and the leakage rate increases greatly from 0.812 m L/s to 3.0 m L/s at rotational speeds of 100 to 300 r/min.It has a minimum opening force and maximum leakage rate.Its sealing performance is poor.2.The modulus of fiber wingding composite is positively correlated with fiber volume fraction,while Poisson’s ratio is negatively correlated with fiber volume fraction.The material withstand high unidirectional loads at winding angles of 0° and 90°,while it withstand shear loads well at winding angles of ± 45°.The wear of composite material first manifests as adhesive wear,and then develops into abrasive wear,during which resin flaking and fiber microcracking occur.The end face’s temperature of the winding composite/alloy sealing pair is larger.Within the rotational speeds of 100～300 r/min,the opening force of sealing pair increases linearly from 9.02 k N to 14.68 k N,the leakage rate is stable of about 0.6 m L/s.Its comprehensive sealing performance is the best.3.The performance of braided fiber composite is balanced on the braided surface.Its wear mechanism is similar to fiber wingding composite,but this material causes complex damage to fiber at the point of interweaving,and the fiber inside yarn are micro-cut,resulting in higher friction and greater wear.The end face’s temperature of the braided composite/alloy sealing is small.Within the rotational speeds of 100～300 r/min,the opening force of sealing pair increases linearly from 4.13 k N to 8.95 k N,and the leakage rate increases slightly from 0.784 m L/s to1.816 m L/s.Its sealing performance is better than Thordon sealing pair.