Dynamic characteristics of fully-partitioned pocket damper seal working with high parameters
The three-dimensional numerical model of fully-partitioned pocket damper seal(FPDS)was estab-lished by computational fluid dynamics method.The effects of high inlet pressure,rotational speed and preswirl ratio on the dynamic characteristics of FPDS were studied based on multiple-frequencies elliptic whirling orbits.Results showed that keeping the inlet pressure 7 MPa,the effective damping increased and the crossover frequency decreased with the increasing pressure ratio.For pressure ratio 7,the effective damping increased sharply with the increasing inlet pressure.For inlet pressure 7 MPa,the effective damping was about 10.26 times that of inlet pressure 0.69 MPa,and the system stability was enhanced.Compared with the rotor rotational speed 5 000 r/min,the crossover frequency increased by about 62.2 Hz for rotor rotational speed 25 000 r/min,the effective damping decreased by about 28.5％,and the cross-coupled stiffness increased by about 6.94 times.However,the increase of rotational speed caused vortex in the cavity,which was conducive to reducing the leakage flowrate.The system stability performed best for the preswirl ratio 0.When preswirl ratio increased to 0.8,the cross-coupled stiffness increased by about 4.84 times,and the crossover frequency increased by 24.9 Hz.The effective damping decreased,resulting in the decrease of system stability.
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