偏心密封内切向气流力及其对稳定性影响的理论与试验研究  

Theoretical and Experimental Research of Tangential Fluid-induced Force and Its Influence on Stability in Eccentric Seal

作　　者：张万福[1] 杨建刚[1] 曹浩[1] 郭瑞[1] 孙丹[1] 

机构地区：[1]东南大学火电机组振动国家工程研究中心,南京210096

出　　处：《机械工程学报》2011年第17期92-98,共7页Journal of Mechanical Engineering

基　　金：国家自然科学基金资助项目(50875045)

摘　　要：建立气缸—密封系统动力学分析模型,提出一种新的密封内气流力及刚度系数识别方法。应用双控制体模型对偏心密封腔内压力分布及切向气流力产生机理进行分析。理论研究表明各密封腔内压力近似呈正弦分布,压力高点沿轴向偏离最小间隙处的角度不断增大。随密封交叉刚度的增大,系统稳定性降低,当其超出一定范围时会导致系统失稳。试验研究转速、进气压力、偏心、密封间隙等因素对气流力的影响。试验发现在垂直于转子偏心方向上会产生一个较大的切向气流力,并且切向与径向气流力的差值随转速升高逐渐增大。随进气压力升高、密封间隙的减小,切向和径向气流力都增大,并且切向气流力较径向气流力增长幅度更为明显。在切向气流力的作用下气缸对数衰减率随转速升高逐渐下降,系统稳定性降低。A dynamic analysis model for cylinder-seal system is set up,and a new identification method for fluid-induced forces and stiffness coefficients in seals is presented.The pressure distribution and the generation mechanism of tangential fluid-induced forces are analyzed based on the two-control-volume model in eccentric seals.The theoretical studies show that the pressure distribution is sinusoidal approximately,and the angle of high pressure points deviation from the minimum clearance is increasing along the axis.The system stability decreases with the increasing cross-coupled stiffness in a certain range.Beyond this range,the system will be destabilized.Influences of rotating speed,inlet pressure,eccentricity and clearance on fluid-induced force are tested in the rig.It is found that a large tangential fluid-induced force is produced in the direction perpendicular to the eccentric displacement of rotor.The differences between the tangential and radial fluid-induced forces become larger and larger with increasing rotating speeds.Under the action of the forces,the logarithmic decrement of the cylinder descends with increasing rotating speeds,and the system stability decreases.

关 键 词：气流激振 密封 气流力 刚度系数 双控制体 

分 类 号：TK263.2[动力工程及工程热物理—动力机械及工程]