An Experimental Study of Static and Dynamic Characteristics for Annular Plain Seals with Porous Materials

对三种圆孔型阻尼密封和一种烧结金属衬套平面密封的静、动态特性进行了试验研究。阻尼器密封件由一个厚度为0.5mm的内部穿孔环（SUS304）和一个固定环的衬套（SUS304）组成，该穿孔环具有约3800个直径为0.4mm的圆孔，孔间距为2mm。这些孔位于轴向平面中，并且对于阻尼器密封件1垂直于内表面（径向方向），对于阻尼器密封件2从60度方向垂直于内表面，并且对于阻尼器密封件3从30度方向垂直于内表面。另一种密封（多孔密封）具有插入密封入口部分的烧结金属衬套，因此，密封表面由两种不同的材料组成：固体（SUS304）和烧结金属（SUS304）试验结果表明，阻尼密封与普通实心环形密封相比，阻尼密封具有更高的密封性能摩擦损失系数λ和名义入口压力损失系数Xi的最大值，泄漏流量Q小于固体密封。λ的值按固体密封件、阻尼密封件1、阻尼密封件2和阻尼密封件3的顺序变高而Q变小。此外，阻尼器密封2和3的切向流体力减小，这有利于反向涡旋运动，并导致在相对高的转速下的高稳定性操作，与其他密封相比。另一方面，观察到多孔密封和固体密封之间的性能特性的定量差异是微不足道的。这一事实归因于由于较高的间隙比而由烧结金属引起的流体静力的减小。

The static and dynamic characteristics are experimentally investigated for three types of damper seals with round-hole pattern and a plain seal with sintered metal bush. The damper seals consist of an inner perforated ring of 0.5mm thickness (SUS304) having about 3800 round holes of 0.4mm diameter at intervals of 2mm and a bush (SUS304) holding the ring. These holes lie in the axial plain, and are made perpendicularly to the inner surface (radial direction) for damper seal 1, from the 60 degrees direction to one for damper seal 2 and from the 30 degrees direction for damper seal 3. The other type of seal (porous seal) has the sintered metal bush which is inserted into the inlet part of the seal, and consequently, the seal surface consists of two different materials: solid (SUS304) and sintered metal (SUS304).The results of this test program support the following conclusions.A comparison of the damper seals and the ordinary solid annular plain seal shows that the damper seals take higher values of the friction loss coefficient lambda and the nominal inlet-pressure loss coefficient xi , and smaller leakage flow Q than the solid seal. The value of lambda becomes higher and Q smaller in order of the solid seal, damper seal 1, damper seal 2 and damper seal 3. Furthermore, the tangential fluid forces for damper seal 2 and3 are reduced, which facilitate the backward whirling motion and lead to a high stable operation at relatively high rotational speed as compared to that for the other seals.On the other hand, it is observed that the quantitative difference of performance characteristics between the porous seal and the solid seal is insignificant. This fact is ascribed to the reduction in the hydrostatic force induced by the sintered metal owing to higher clearance ratio.