Leakage flow in 2-D constant rotor diameter stepped labyrinth seals is investigated by means of pressure andvelocity field measurements and numerical simulation of 2-D and axisymmetric models. The basis of investigation is ageneric stepped labyrinth seal currently used in industry in team turbine generators. The performance of the baseline sealdesign was compared with new seal designs with specific features changed in order to examine their influence on leakagecharacteristics through such seals. Numerical modeling andexperiments were performed over a range of seal pressure ratiosfrom 1 to 10. A number of configurations were evaluated both experimentally and numerically. This paper discusses flowdetails associated with only one configuration as comparedwith the baseline. Results have been helpful in the understanding of seal flow leakage and total pressure lossmechanisms. Mechanisms of leakage reduction in labyrinth
seals included turbulence induced viscous losses, chamber vortex generation, flow stagnation losses, and increased flowstreamline curvature. Numerical results provided insight into the flow field details and were helpful in facilitating basic physical understandings used for improved seal designs.