EFFECT OF AXIALLY GROOVED OIL SEALS ON THE LEAKAGE FLOW AND STABILITYOF A CENTRIFUGAL-COMPRESSOR

The results of an. analytical investigation are given for the effect o f axially grooved floating oil ring seals on the leakage flow and stab ility of a centrifugal gas compressor. The finite element method was u sed to solve the non-linear and coupled hydrodynamic and thermal equat ions for pressure and temperature distributions in the oil seal ring w ith and without the axial grooves. The peturbation technique was used to obtain the static and dynamic characteristics of the oil seal. The results for selected cases of axial grooving are presented in graphica l form for operation at various eccentricities. The non-dimensional le akage flow results correlate well with previously published results ca lculated by narrow groove theory. The stability of a multi-stage gas c ompressor is evaluated for different configurations of the oil seal gr ooving geometry. The compressor rotor shaft finite element model inclu des a multi-level analysis for the oil seal rings that permits the eva luation of the floating seal influence on the total system stability. Results are given for both low and high-pressure sealing conditions, w hich simulate test stand and field operating conditions. The results s how that the added grooves enhance the stable operation of the rotor s ystem for low pressure fixed seal conditions and reduce the system sta bility at lower eccentricities for low-pressure floating seal conditio ns. In high pressure conditions the added grooves enhance the stabilit y of the system for both fixed and floating seal conditions.