Abstract: The property of labyrinth seal relies on the throttling process in clearance and the dynamic dissipating process in cavity, these two procedures play decisive roles in essential to the sealing property of the labyrinth. Study on the flow field in labyrinth seal is helpful for us to make use of some characters of turbulence in improving the sealing property.　Model experiment and numerical simulation are adopted to study the seal mechanism of a crenellated radial labyrinth. It is shown that flow deflection in throttle clearance can effectively decrease the actual flow area in the clearance and improve the seal property. Thus the flow deflection in throttle clearance can be utilized to replace the small clearance, and a better seal property can be achieved under condition of wide clearance. This is of great importance to the design, production and operation of labyrinth, and lays a foundation for the invention of newly constructed labyrinth seal.

Key words: Resistance enhancement by turbulence, Flow deflection, Flowfield simulation, Labyrinth seal, Seal mechanism