旋转机械转子轴萌生裂纹后，瞬态加速过程中转涡差角时变使裂纹周期性开合，系统发生不同于稳态情况的振动。本文基于中性轴法确定裂纹开合，数值计算了呼吸裂纹引起刚度时变的转子过临界转速的瞬态振动，分析了裂纹大小、方向角和重力对线性加速转子瞬态振动的影响，以及定功率加速瞬态过程中系统振动响应及稳定性。结果发现，瞬态条件下带呼吸裂纹转子系统亚谐波共振并不明显；裂纹越大，过临界转速时瞬态振幅越大；在临界转速附近裂纹瞬时张开会激起很大的振动；定功率加速过程下，若功率不足够提供转子顺利穿过临界转速，则会出现外界扭矩与瞬态振动的能量耦合，大裂纹还可能造成瞬态振动发展成混沌。
Abstract
When crack emerges in shaft of rotating machinery rotor, time-varying rotation-whirl phase difference makes crack open and close periodically, which makes transient vibration of rotor different from its steady vibration. The neutral axis method was adopted to determine the crack opening and closing, and the transient vibration response caused by crack breathing of single disc rotor crossing critical speed was calculated numerically, and the influence of crack depth, orientation angle and gravity on speeding-up rotor with linear acceleration, and transient vibration characteristics and stability of system speeding-up with constant power were analyzed. The results show that the sub-harmonic resonance of breathing crack rotor is not obvious in transient process; The deeper crack is, the larger transient amplitude crossing critical speed is; when crack opens near critical speed, intense transient vibration will be excited; When crack rotor accelerates with constant power, if the power is not enough to provide the rotor smoothly through the critical speed, the outside torque and transient vibration will couple over energy, and with big crack in shaft, chaotic vibration may occur.
关键词
中性轴法 /
呼吸裂纹 /
临界转速 /
单盘转子 /
瞬态振动
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Key words
neutral axis method /
breathing crack /
critical speed /
single rotor /
transient vibration
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