Effects of bulges on the seal performance of rub-grooved labyrinth seal

As the most widely used non-contact sealing structure in aero engines and gas turbines, labyrinth seal is often used to reduce the leakage of compressor and turbine regions. During the working process of engines, the rub-grooves are formed, due to the abrasion of the bushing, which leads to the increment in the leakage of the labyrinth seal. To improve the seal performance of a rub-grooved labyrinth seal, seals with bulges have been numerically investigated. Results show that both pressure ratio and bugles' size have strongly effect on the seal performance of rub-grooved labyrinth seals. Compared to non-bulge seal, bulges destroy the continuity of the jet boundary layer and change the direction of the jet flow, which decrease the leakage effectively. The discharge coefficient can be decreased 32%, when the pressure ratio is 2. The results show that the most important parameter that influences the discharge coefficient is the height of bulge. The seal efficiency can be raised 20%, when the bulge' s height is 0.1mm, and when the height is 0.3mm, the seal efficiency can be raised to 40%. Bulge's width has some effect on seal performance, but not obvious. Within the scope of this study, data also reveal that the relative position between the bulge and rub-groove has little influence on rub-grooved labyrinth seal·