07/20-23/03 STRUCTURAL AND DYNAMIC CONSIDERATIONS TOWARDS THE DESIGN OF A PADDED

Finger seals present a compliant seal alternative to brush seals and through their geometric configuration bring about the added potential of hydrodynamic lifting and thus non-contacting operational feature. The fingers ’ compliance allows both axial and radial adjustment to rotor excursions without damage to the integrity or performance of the seal. The work to be presented here concerns the mapping of the thermofluid and dynamic behavior of repetitive section of the newly proposed design of a two layer Finger Seal. The assembly contains four high pressure (HP) and four low pressure (LP) fingers arranged axially in a staggered configuration, and subject to an axial pressure drop. The numerical 3-D results presented herein were obtained using customized commercial packages CFD-ACE+. The results were obtained in a parametric fashion were the HP side, and the compressibility are the controlling parameters. In addition, two limiting thermal cases were also studied in conjunction with the previously mentioned parameters. The entire study is aimed at generating reliable design procedures for the parametric design of a finger seal. It was found that the geometry proposed provides satisfactory lifting capability for the fingers; that the stiffness of the finger is comparably small to that of the fluid, and thus the displacement transmissibility is mostly close to 1. The stiffness and damping characteristics of the solid padded finger and that of the fluid are also studied and presented on a parametric basis