Brush seals can improve engine performance by reducing leakage. Wear models of brush seals provide methods to predict wear and leakage. However, rotor eccentricity, radial deformation, and hysteresis effect of bristles are not considered systematically in the existing models, which may lead to large errors in some cases. To investigate the influence of rotor-stator eccentricity and radial deformation on the wear process and leakage performance of brush seal, a brush seal test was planned and executed, in which the air leakage rates were measured at different testing times and operating conditions, the eccentricity and radial deformation was measured using eddy current sensors. The test results showed that the eccentricity and radial deformation significantly affected the wear behavior and leakage performance. In the theoretical research, the abrasive wear equation is adopted to describe the material loss of bristles, and a simplified description is used to express the rotor-stator eccentric motions. To describe the effect of hysteresis on wear behavior, the deformation of the bristle pack is divided into rebounding deformation and locked deformation, and the two deformation modes are modeled separately. Then a brush seal wear model considering rotor-stator eccentricity and radial deformation is obtained, in which the hysteresis effect is especially represented. The wear model was verified quantitatively based on the brush seal test data, and the results show that there is an error of 20% with the calculated wear loss when rotor eccentricity, radial deformation, and hysteresis effect are comprehensively considered. In contrast, ignoring the hysteresis effect may increase the error by several times. This study provides a quantitative and practical method for predicting the wear and leakage of brush seals.

Graphene is often used to improve interlaminar fracture toughness of carbon fiber/epoxy resin (CF/EP) composites. It is still a challenge to improve the toughness while maintaining the in-layer properties. In this study, 2D graphene oxide carbon fiber reinforced epoxy resin matrix (2D CF-GO/EP) composites were prepared by a vacuum infiltration hot-press forming experimental system (VIHPS), and three-point flexural and end notch flexural (ENF) tests were carried out. With the increase of the fiber mass fraction in the composites, the mode II interlaminar fracture toughness (G_IIC) layers decrease gradually, and the bond property between the fiber and matrix interface layer becomes worse, because the accumulation of dense fiber bundles reduces the matrix penetration ability of cracks. However, the flexural properties increased first and then decreased, and reached the best flexural properties at 64.9%. When the fiber mass fraction is too high, the interlamellar bonding properties will decrease, and the fiber bundles will compress and affect each other. The delamination phenomenon will occur between the layers of the composites, which affects the overall bearing strength and stress limit of the composites. The results of the study show that the composites prepared by VIHPS have excellent mechanical properties, and the content of carbon fiber plays an important role in the influencing factors of the interlaminar and in-layer properties of composites.

In order to find a solution for the oil leakage problem of a large clearance shaft seal on a marine diesel engine, a series of improvement measures were proposed based on the mechanisms of centrifugal separation, reverse pumping, oil groove and staggered labyrinth. A shaft seal test system that can simulate the gas-liquid environment was built, and verification tests were conducted. Test results showed that the oil leakage didn’t decrease after adding radial or inclined ribs on the oil slinger but increased significantly instead. Adding an oil groove on the oil baffle also didn’t reduce any oil leakage. Fortunately, the addition of the staggered labyrinth effectively reduced the oil leakage. By combining with CFD simulation, the test results were explained, and the sealing functions of different structural features were studied. For structural design work of the non-contact shaft seal, the following design suggestions were proposed. First, the centrifugal effect on the liquid medium can be enhanced by adding ribs on the oil slinger, but the obstruction of oil return should be avoided at the same time. Second, the rotational speed should be fully considered when using the reverse pumping effect. Third, the oil guide groove should be adapted to the airflow and rotation state at its location. Finally, the staggered labyrinth has a stronger throttling effect compared with the straight-through labyrinth, which can reduce the outward transportation of oil by airflow.