摘要
针对某30 kW微型燃气轮机用静压气体轴承,开展轴承刚度、承载力及轴系临界转速特征的数值与实验研究。通过离散化可压缩雷诺方程,采用数值迭代方法,获取轴承内气膜压力分布和气膜刚度特性;采用有限元方法,研究转子-轴承系统的模态特性与临界转速;在气体轴承支撑的微型燃气轮机试验台上,采用时域振动信号和不平衡响应曲线等振动测试分析方法,获取轴系的气膜临界转速特性。研究结果表明:研究的该静压气体轴承,其转速在30 000 r/min内动压效应相对于静压效应可以忽略;轴承气膜刚度随着偏心率增大而增大,但当偏心率超过0. 8时,由于出现"静态不稳定区域"导致气膜刚度下降。数值模拟和实验都证实了转子在6 000 r/min和9 000 r/min附近出现了由气膜刚度引起的锥动临界特征。
Numerical and experimental study on bearing stiffness,bearing capacity and critical speed characteristics of a 30 kW micro gas turhine aerostatic bearing was canied out.There will be critical characteristics caused by the bearing gas film before the rotor reaches the first-order bending critical speed of a micro gas turhine supported by gas bearing.This phenomenon was analyzed by numerical simulation and experimental verification.The compressible Reynolds equation was discretized and solved by numerical iteration method to obtain the pressure distribution and the gas film stiffness of the bearing.The modal characteristics and critical speed of the rotor-bearing system was studied by finite element method. Based on the micro gas turhine test bench supported by gas bearing, the critical speed of the gas film of the shaft system was obtained by the vibration test and analysis methods such as time-domain vibration signal and unbalanced response curve.The results show that the dynamic pressure effect of the studied static pressure gas bearing can be neglected compared with the static pressure effect within the the rotational speed of 30 000 r/min.The bearing film rigidity is increased with the increasing of eccentricity.However,when the eccentricity exceeds 0.8,the stiffness of the gas film is decreased due to the ＇ static instability zone＇ .Both numerical simulations and experiments proves that the critical characteristics of the cone motion caused by the stiffness of the gas film appear near the speed of 6 000 r/min and 9 000 r/min.
作者
李子君
韩东江
杨金福
毕春晓
郝龙
雷欢
LI Zijun;HAN Dongjiang;YANG Jinfu;BI Chunxiao;HAO Long;LEI Huan(University of Chinese Academy of Sciences,Beijing 100049,China;Institute of Engineering Thermo Physics,Chinese Academy of Sciences,Beijing 100190,China)
出处
《润滑与密封》
CAS
CSCD
北大核心
2018年第11期52-58,共7页
Lubrication Engineering
基金
国家自然科学基金项目(11602268)
关键词
气体轴承-转子系统
雷诺方程
气膜刚度
振动模态
临界转速
gas bearing-rotor system
Reynolds equation
gas film stiffness
vibration mode
critical speed
