Experimental analysis on the influence of Rayleigh stepped pockets on the leakage and tribological characteristics of the segmented annular seal

In response to the problem of oil leakage caused by the wear of the main sealing surface due to the insufficient hydrodynamic pressure effect in the segmented annular seal applied in aero-engines, test pieces of segmented annular seal featuring Rayleigh stepped pockets were designed and processed. An experimental platform was constructed for the purpose of investigating the leakage and tribological characteristics of segmented annular seals. Experimental studies on the leakage and tribological characteristics of Rayleigh stepped pocket segmented annular seal (PSAS) and traditional segmented annular seal (TSAS) were carried out. The results indicate the increase in rotational speed, pressure difference and the decrease in inlet temperature leads to the increase of leakage. When subjected to the same conditions, TSAS main sealing surface displays typical abrasive and adhesive wear patterns, while, PSAS main sealing surface exhibits only adhesive wear. Rayleigh stepped pocket reduces the wear of the segmented annular seal. The increasing rotational speed, pressure difference and inlet temperature lead to the increase of casing temperature of the segmented annular seal. At 298 K and 633 K, compared with TSAS, the leakage of PSAS increases by an average of 10.59 %∼13.44 % and 9.83 %∼18.44 %, respectively, and the temperature of PSAS seal casing decreases by an average of 11.26 % ∼11.5 % and 8.45 % ∼8.75 %, respectively. Hydrodynamic pressure effect generated by the Rayleigh steeped pocket can increase the segmented annular seal equivalent clearance, reduce wear of the main sealing surface, and enhance the air-to-segment convection heat transfer.