Sharper Labyrinth Seal Edges to Allow Greater Clearance Without Increased Leakage

Abstract

A numerical study was undertaken to examine the effects of utilizing sharper edges for increasing the leakage resistance of advanced labyrinth seal configurations. Such an increase allows the designer to enlarge the extremely small knife clearance, providing a seal with less damage susceptibility at the same leakage rate. The maximum possible leakage resistance increase from changing three cavity edges to perfectly sharp ones was estimated from the present computations. In addition, previous measurements of the edge sharpness effect on the leakage through orifices are appropriately utilized to obtain a rough estimate of the resistance increase for generic seals. The latter allows consideration of a broader range of application. Further, turbulence energy generation contours reveal that only one particular cavity edge needs to be sharpened in order to obtain a significantly increased leakage resistance.