| dc.description.abstract | Balance piston gas seals restrict leakage at the discharge of centrifugal compressors. There are multiple types including labyrinth seals, textured seals, pocket damper seals (conventional PDS), and fully-partitioned pocket damper seals (FPDS). These annular seals develop large radial forces due to the high pressure differentials and gas density, which have a measureable impact on the compressor’s rotordynamic performance. There is an extensive experimental database available for labyrinth seals and textured seals. However, there is not a comprehensive database for PDS and FPDS to compare against textured seals. This investigation aimed at evaluating the rotordynamic performance of FPDS. Dynamic force coefficients were experimentally identified for the FPDS operating with three preswirl levels (Low, Medium, High), three pressure ratios (25%, 50%, 65%), and three rotor speeds (10, 15, 20 krpm). The results show the FPDS develops either similar effective damping coefficients or higher, for particular cases, when compared to a honeycomb seal.
At low preswirl, the FPDS displays similar to higher effective damping values at synchronous to super-synchronous frequencies. The main difference between honeycomb and FPDS lies in their direct stiffness and leakage values. Honeycomb seals develop relatively large stiffness coefficients, whereas FPDS display either negative or negligible stiffness values depending on the pressure ratio. The FPDS leaks roughly ~33% more than the honeycomb seal. With these results, it is concluded that the FPDS should be chosen in a case-by-case situation, considering the location of the system natural frequencies, rather than an over-all replacement for textured seals. | en |
