摘要
弹性箔片轴承支承的转子在高速旋转时,转子可能会和轴承发生碰摩。为了揭示当转子采用不同结构刚度箔片支承时,该冲击对转子振动的影响机理,针对2个径向GFBs支承的刚性转子系统模型,应用龙格库塔法求解转子动力学状态方程,获得3种结构刚度箔片(均匀刚度箔片、软箔片、硬箔片)下的轴颈位移。推导出箔片轴承的等效刚度和等效阻尼系数,发现当轴颈无涡动时,箔片轴承的等效刚度正好是气膜刚度和箔片结构刚度的串联;而当轴颈有涡动时,箔片轴承的等效刚度和等效阻尼均是结构刚度、结构阻尼和涡动频率的函数,且当轴颈涡动频率趋于无穷大时,上述等效刚度和等效阻尼趋于无涡动时的值。计算表明,当采用恒定刚度箔片时,转子稳态振幅最小,但是瞬态响应时间较长;当采用非线性软箔片时,转子稳态振幅最大,但是瞬态响应时间最短。当增大非线性箔片的结构刚度时,转子稳态振幅会减小,瞬态响应时间会增加。因此,箔片的设计需要辅以轴承-转子动力学特性的考量,以获得箔片结构刚度和结构阻尼的合理匹配。
The rotor supported by gas foil bearings(GFBs)may collide with the bearings at a high speed.In order to reveal the mechanism of the impact on rotor vibration when the rotor is supported by GFBs with various structural stiffness,the paper takes a 2 GFBs-rigid rotor system models as examples,uses the Runge-Kutta method to solve the state equation of rotor dynamics,and obtains the journal displacements of the rotor supported by three different structural stiffness foils(uniform,soft,and hard foils).The equivalent stiffness and damping coefficient of foil bearing are derived.It was discovered that the equivalent stiffness of the GFB is the series connection of the gas film stiffness and the foil structural stiffness for the static journal.The equivalent stiffness and damping of the GFB are functions of structural stiffness,structural damping and vortex frequency,and approach to the values of the static journal when the vortex frequency becomes infinity.The results show that the steady amplitude of rotor is the smallest,but the transient response time is longer when the constant stiffness foil is used;for the nonlinear soft foil,the steady amplitude of the rotor is maximum,but the transient response time is minimum;when the structural stiffness of the nonlinear foil is increased,the steady amplitude of rotor decreases and the transient response time increases.Therefore,the design of foil needs to be supplemented by the consideration of the dynamic characteristics of the bearing-rotor in order to obtain a reasonable match of the structural stiffness and damping of the foil.
作者
程文杰
邓志凯
肖玲
李维
钟斌
樊红卫
李明
CHENG Wen-jie;DENG Zhi-kai;XIAO Ling;Li Wei;ZHONG Bin;FAN Hong-wei;LI Ming(College of Sciences,Xi’an University of Science and Technology,Xi’an 710054,China;Center for Post-Doctoral Studies in Mechanical Engineering,Xi’an University of Science and Technology,Xi’an 710054,China;College of Mechanical Engineering,Xi’an University of Science and Technology,Xi’an 710054,China)
出处
《西安科技大学学报》
CAS
北大核心
2019年第5期912-918,共7页
Journal of Xi’an University of Science and Technology
基金
国家自然科学基金(51705413,51705416,51605380,11502196,11972282)
中国博士后(2017M613291XB,2016M602842,2015M580865)
陕西省自然科学基金(2014JM1015)
西安科技大学博士启动金(2017QDJ013)
关键词
弹性箔片轴承
等效刚度
等效阻尼
瞬态冲击
稳态响应
Gas Foil Bearings(GFBs)
equivalent stiffness
equivalent damping
transient shock
steady state response
