高参数贯通式袋型阻尼密封动力特性

Dynamic characteristics of fully-partitioned pocket damper seal working with high parameters

采用计算流体力学方法建立贯通式袋型阻尼密封(FPDS)三维数值计算模型,基于多频椭圆涡动轨迹的密封动力特性求解方法研究了高进口压力、转速及预旋比对FPDS动力特性的影响。结果表明:保持进口压力为7 MPa不变,随压比的增加,有效阻尼增加,穿越频率逐渐减小;压比为7时,有效阻尼随进口压力增加而急剧增大,进口压力为7 MPa时有效阻尼约为进口压力为0.69 MPa的10.26倍,系统稳定性增强显著。当转子转速为25000 r/min时,较转速为5000 r/min,穿越频率可增加约62.2 Hz,有效阻尼约降低28.5%,交叉刚度增长约6.94倍,高转速严重影响系统稳定,但转速增大有利于在腔室内形成旋涡,降低密封泄漏。当预旋比为0时,系统最稳定,当增加到预旋比为0.8,交叉刚度约增长4.84倍,穿越频率约增加24.9 Hz,有效阻尼下降,导致系统稳定性降低。

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 multiplefrequencies 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 5000 r/min,the crossover frequency increased by about 62.2 Hz for rotor rotational speed 25000 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.