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

实验研究了三种圆孔密封和带烧结金属衬套的滑动密封的静动态特性。减振器密封由0.5mm厚的内穿孔环（SUS304）组成，其中约有3800个直径0.4mm的圆孔，间隔2mm，衬套（SUS304）固定环。这些孔位于轴向平面上，对于减振器密封1，从60度方向垂直于内表面（径向），对于减振器密封2，从30度方向垂直于内表面。另一种类型的密封（多孔密封）有烧结金属衬套插入到密封的进口部分，因此，密封面由两种不同的材料组成：固体（SUS304）和烧结金属（SUS304）。该测试程序的结果支持以下结论。通过与普通固体环空平面密封的比较，发现阻尼密封的摩擦损失系数lambda和公称进口压力损失系数xi都比固体密封高，泄漏流量Q比固体密封小。阀芯密封、阀芯密封1、阀芯密封2、阀芯密封3的λ值越大，Q值越小。此外，减振器密封2和3的切向流体力减小，有利于向后旋转运动，与其他密封相比，可以在相对较高的转速下稳定运行。另一方面，观察到多孔密封与固体密封性能特征的数量差异不显著。这是由于较高的间隙比使烧结金属引起的静水力减小所致。

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.