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针对传统频域识别密封动力特性系数方法存在的问题,提出利用转子不平衡实现同频激励,在2组不平衡状态下构建4个独立方程,建立密封动力特性系数识别模型。在密封试验台上研究了转子不平衡、转速、进出口压比等因素对密封动力特性系数的影响。试验结果表明动力特性系数中直接项系数相近,交叉项大小相同,符号相反。随着进出口压比和转速的增大,8个密封动力特性系数都增大,直接刚度项增大幅度较交叉刚度项更为明显,直接阻尼项增大幅度与交叉阻尼项接近。同时发现相对振动大小对动力特性系数影响并不大。对影响动力特性系数识别精度的因素进行了分析,提出了试验转速、不平衡工况的合理选择方法。
Aiming at the problems existing in the traditional frequency domain method of identifying the dynamic characteristic coefficient of seal, this paper proposes to use the rotor unbalance to realize the same frequency excitation and build four independent equations in two groups of unbalanced states. The model of seal dynamic characteristic coefficient identification is established. The effect of rotor unbalance, rotation speed, pressure ratio between inlet and outlet on dynamic characteristic coefficient of seal was studied on the seal test bench. The experimental results show that the coefficients of the direct coefficients in the dynamic characteristic coefficients are similar, and the cross terms have the same size and opposite signs. With the increase of the pressure ratio and speed of the inlet and outlet, the dynamic characteristic coefficients of the eight seals all increase, the direct stiffness increases more obviously than the cross stiffness, and the increase of the direct damping is close to that of the cross-damping. At the same time, it is found that the relative vibration has little effect on the dynamic characteristic coefficient. The factors influencing the identification accuracy of dynamic characteristic coefficient were analyzed, and a reasonable selection method of test speed and unbalanced working condition was put forward.