可倾气封与固定气封性能试验比较分析

提出一种新型可倾气封。与传统固定式气封相比,可倾气封块在气流力作用下可以绕支点作自适应摆动,当气封块达到平衡位置时,切向激振力减小,从而提高稳定性。试验采用不平衡同频激励法测定可倾气封的动力特性,研究和比较了可倾气封和传统固定式气封的动静态性能。试验结果表明,两种气封泄漏量相当,可倾气封内产生的切向气流力比固定气封小。低压比下两种气封动力特性系数相近,随着压比的增大,动力特性系数差异逐渐增大。以气流力对气缸的做功量大小为综合评判依据,发现可倾气封做功量明显小于固定气封,压比越大,做功量差异也越大,可倾气封的稳定性较高。对于大型旋转机械而言,气封进出口压比很大,两种气封动力特性的差异将会更大。

Experimental Analysis and Comparison for Characteristics of Tilting-pad Seal and Fixed Seal

A new type of tilting-pad gas seal is referred.Compared to traditional fixed gas seal,the seal block of tilting-pad seal can swing about a pivot automatically under the air force.The stability can be improved through reducing the tangential force when the seal pads reach equilibrium position.The dynamic characteristics of tilting-pad seal are tested by experiment using unbalance synchronous frequency excitation method.Also,the experiment is taken to compare the characteristics of two kinds of seals.The result shows that the leakage of tilting-pad seal is close to fixed seal,and the tangential force generated in tilting-pad seal is smaller than the fixed.The rotordynamic coefficients of two kinds of seals are tested under different pressure ratios.It is shown that the rotordynamic coefficients are almost equal in low pressure ratio,but the difference between two seals increases as the pressure ratio increasing.The work acted on cylinder system is used as standard to judge the stability of seal.The calculation result shows that the fixed seal does more work than tilting-pad seal to cylinder system.As the increasing of pressure ratio,the work difference increases,so the tilting-pad seal has higher stability.For the real large rotating machines,the inlet/outlet pressure ratio is very high,so the difference between these two kinds of seals is larger.