Patent ID: 8540479

Claim:
An active retractable seal assembly for use between rotating and non-rotating turbomachinery components comprising: at least one seal ring mounted to the non-rotating component, said at least one seal ring movable toward and away from the rotating component between respective closed and open positions as a function of pressure drop across the seal ring said at least one seal ring biased toward said open position by one or more actuators; a fluid bypass circuit for directing fluid around said at least one seal ring to reduce the pressure drop across the seal ring; wherein said fluid bypass circuit includes a conduit extending from an inlet at a location upstream of said at least one seal ring and terminating at an outlet location downstream of said at least one seal ring, and wherein a bypass control valve is located in said fluid bypass circuit, between said inlet and said outlet, said control valve enabling active control of pressure drop across the seal ring such that said at least one seal ring can be moved via said one or more actuators to said open position during operation and under any operating conditions of the turbomachinery.