A NEW APPROACH FOR STABILIZING LABYRINTH SEAL LEAKAGE

A parametric study of geometrical effects on labyrinth seal leakage resistance was conducted using a recently developed Navier-Stokes finite difference code. Previously unavailable design data in terms of an effective cavity friction factor was obtained. Also, a new leakage stability design approach was found, and the parametric study data was used accordingly in designing a seal with non-uniform cavities for the new high-pressure oxygen turbo-pump of the space shuttle main engine. The leakage resistance showed significantly greater stability over an extremely wide range of rotor Further, an enhanced basic understanding of the effect of sharp knife comers on cavity friction factor is obtained from contours of intense turbulence generation. The location of these contours shows that it is the sharp streamline curvature at high velocity slightly upstream of the vena contracta which provides the primary intense turbulent friction. This is a departure from the previous belief that the large turbulent stresses near the edge of the vena contracta are primarily responsible. This finding is expected to be helpful in designing more advanced knife configurations.