Hydrodynamic performance of liquid film seals in circumferential beveled-step spiral grooves

doi:10.11949/j.issn.0438-1157.20161561

Abstract

Abstract:

To reduce liquid film pressure loss in liquid flow divergent zone between sealing surfaces and to improve sealing performance, structure of circumferential beveled-step was introduced into rectangular section spiral groove and corresponding physical model was established. Based on the JFO cavitation model, effects of bevel angle ratio on liquid film pressure distribution, cavitation occurrence, and liquid film hydrodynamic performance were studied at different groove depths. When bevel angle ratio was below 1/30, liquid film pressures of downstream and upstream pumping liquid film seals along circumferential and spiral line direction were enhanced rapidly but cavitation area ratio was dropped sharply, which was more significant for upstream pumping seals. With the increase of bevel angle ratio, leading edge pressure at liquid film rupture showed an increasing trend and trailing edge pressure at liquid film reformation showed opposite trend, but cavitation area ratio increased first and decreased later. The increase of groove depth contributed to the increase of liquid film pressure and the decrease of cavitation area ratio. When groove depth ranged from 8 to 12 μm and bevel angle ratio ranged from 0.1 to 0.3, the load-carrying capacities of both liquid film seals reached to peak values with about 13.5% maximum amplification for the former and about 28% for the latter, whereas increase of friction torque was smaller with about 4.6% maximum amplification. The leakage change along with the increase of bevel angle ratio was similar to the load-carrying capacity.

Key words: spiral groove liquid film seals, circumferential beveled-step, hydrodynamic performance, liquid film pressure, cavitation area ratio

摘要：

为降低密封面间液体流动发散区液膜压力损失及提高密封性能，在矩形截面螺旋槽中引入周向斜面台阶结构并建立物理模型。基于JFO空化边界，探讨了不同槽深时，斜面转角比对液膜压力、降低空穴发生及流体动压性能的影响。结果表明：当斜面转角比小于1/30时，下游泵送或上游泵送液膜密封的周向膜压或螺旋线方向膜压均得到迅速提升而空化面积比迅速降低，尤其是上游泵送密封；随斜面转角比增大，空化面积比先增大后减小，空穴区中液膜开始破裂位置前缘压力呈增加趋势，而液膜重生成位置后缘压力反之。槽深的增加有助于提升液膜压力和降低空化面积比，当槽深为8～12 μm，在斜面转角比为0.1～0.3时，两类型液膜密封承载能力均可达到最大值，前者最大增幅约13.5%，后者约28%；摩擦扭矩最大增幅约4.6%，增幅较小；泄漏量随斜面转角比的变化规律与承载能力相似。

关键词: 螺旋槽液膜密封, 周向斜面台阶, 流体动压性能, 液膜压力, 空化面积比

CLC Number:

TH117.2

LI Zhentao, HUANG Baipeng, HAO Muming, SUN Xinhui, WANG Yunlei, YANG Wenjing. Hydrodynamic performance of liquid film seals in circumferential beveled-step spiral grooves[J]. CIESC Journal, 2017, 68(5): 2016-2026.

李振涛, 黄佰朋, 郝木明, 孙鑫晖, 王赟磊, 杨文静. 周向斜面台阶螺旋槽液膜密封流体动压性能[J]. 化工学报, 2017, 68(5): 2016-2026.

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