基于变厚度挡板的新型渐扩/渐缩袋型阻尼密封动力特性研究

Study on Dynamic Characteristics of Pocket Damper Seals with Divergent/Convergent Cavity

对传统贯穿式袋型阻尼密封进行改进,通过改变其挡板沿轴向厚度,实现腔室体积沿轴向渐扩/渐缩。建立渐扩式、渐缩式及传统贯穿式袋型阻尼密封结构数值计算模型,应用基于微元理论的密封动力特性系数理论识别方法研究了渐扩(缩)角、进出口压力、转速对新型密封动力特性的影响。结果表明:新型渐扩/渐缩袋型阻尼密封的有效阻尼系数均大于传统贯穿式袋型阻尼密封,其中渐扩式袋型阻尼密封稳定性最好,且3种密封穿越频率变化较小;渐扩(缩)角越大,密封有效阻尼越大;在高频下,有效阻尼系数随进出口压差增大而逐渐增大;转速的升高会降低密封有效阻尼系数,增大穿越频率,进而降低系统稳定性。

The traditional fully partitioned pocket damper seal was modified by varying the baffle thickness along the leakage direction.Then the cavity volume was changed divergently and convergently in the axial direction.A computational fluid dynamics(CFD)model of the divergent,convergent,and traditional pocket damper seals was established.The identification method using the infinitesimal theory was applied to predict rotordynamic coefficients of pocket damper seals.The effects of the divergent/convergent angle,inlet and outlet pressure,rotational speed on rotordynamic characteristics were analyzed.Results show that the effective damping coefficients of the novel divergent/convergent pocket damper seal are larger than those of the traditional fully partitioned pocket damper seals.The divergent pocket damper seals possess the best stability,and the three kinds of seals show little changes in their crossover frequencies.The large divergent/convergent angle tends to enhance the effective damping.With the increase of pressure difference,the effective damping coefficient increases gradually at high frequencies.The increase of rotational speeds will reduce the effective damping and increase the crossover frequency.The increasing rotational speed deteriorates the system stability.