Loss Assessment Method of Fluid Curtain–Labyrinth Seals and Action Mechanism of Key Parameters on Seal Performance in a Turbine Rotor Tip

The combination of labyrinth seal and fluid curtain seal can significantly reduce the leakage rate. A loss assessment method of fluid curtain–labyrinth seals in axial turbines with supercritical carbon dioxide as working medium is proposed, and the action mechanism of key parameters is systematically investigated in this paper. The results indicate that combining the loss assessment method with the simplified model calculations can effectively evaluate the loss characteristics of different fluid curtain–labyrinth sealing structures, saving assessment time greatly. With regard to the action mechanism of key parameters on seal performance, as jet angle and seal cavity height decrease, leakage flow rate and loss decrease. A ratio of the jet width to the seal cavity height of 0.1 will minimize leakage losses. The proposed method can be applicable to various types of seals for any working fluid, and the action mechanism can provide guidance for the design and optimization of fluid curtain–labyrinth seals.