US Patent 7445213 Stepped labyrinth seal

A stepped labyrinth seal for a turbomachine, the seal having a stepped portion with a redirecting groove formed thereon to redirect a leakage flow through the gap in substantially a reverse direction and onto a surface of the finger such that the dynamic pressure of the leakage flow is not substantially reduced and the static pressure increased. The cavity formed between adjacent fingers has a flow guiding surface that maintains the dynamic pressure of the flow, thereby keeping the flow at high velocity and low static pressure.