Numerical investigation on the leakage characteristics of stepped labyrinth seal

摘要

Labyrinth seals are widely used in gas turbines and steam turbines to reduce leakage flow from high to low pressure regions through gaps. To further explore the factors that influencing leakage characteristics of stepped labyrinth seal, seal clearance and step height were numerically investigated. The geometries investigated represent a typical design of modern gas turbines. A range of pressure ratios, seal clearance and step height were covered in this study. Dimensionless discharge coefficient, describing the sealing performance, was adopted to evaluate in influence of seal clearance and step height on stepped labyrinth seal. The results show that pressure ratio, seal clearance and step height all affect the sealing performance. Seal clearance has a positive correlation with leakage rate, while a negative correlation with discharge coefficient. Comparing to straight-through labyrinth seal, stepped has better seal performance for the blocking effects of steps. Also an optimum step height has been found, which is nearly 2 times of the seal clearance. Future research work will be required to examine the results by experiments.