中文摘要：

转子的热弯曲变形是透平旋转机械热启动出现较大振动的原因之一。燃机停机后,转子在静置过程中与周围空气通过自然对流进行热交换,由于转子上下部冷却的热效率不对称,轴截面将产生温度梯度,转子发生热弯曲变形。分析了停机后的静置过程中,转子在自然对流冷却条件下截面的温度分布、温差变化及热弯曲变形。结果表明：随着静置时间延长,轴截面的温差和转子的热弯曲变形都先增大后减小,但二者的峰值时刻并不相同;若静置时间足够长,最终温差将趋于零,热弯曲变形消失。进一步通过求解弯曲转子的运动方程分析了不同时刻热弯曲变形转子热启动时的振动响应,给出了热弯曲转子热启动时,发生可接受振动水平的允许静置时间。同时验证了转子在发生最大热弯曲变形时刻热启动时,低速盘车对热弯曲变形的有效消除作用。计算结果对燃机转子的正常启停及安全运行具有现实参考意义。

英文摘要：

Rotor thermal bow is one common cause of high vibration of rotating turbo machinery during hot restart.After shutdown of gas turbine,the rotor in standstill condition will exchange heat with the surrounding gas through natural convection.Due to the asymmetrical cooling efficiency between the upper and lower surfaces of the rotor disks,the thermal gradient across the shaft section will develop and result in rotor thermal bow.The temperature distribution and thermal difference of the shaft section as well as the thermal bow of the rotor in natural convection cooling during standstill are calculated.The results show that both the temperature differences of shaft section and rotor thermal bow will gradually increase up to the maximum values and then decrease as time increases.However,their maximums occur at different times.If the standing time is long enough,the temperature differences will close to zero and the thermal bending disappear.Thermal bow induced vibration response of the rotor restarted at different standing time is obtained by solving the equation of motion of the thermal bending rotor.And the permitted standing time to directly restarting the thermal bending rotor is suggested which can lead to acceptable vibration of the rotor with no extra turning.Also is confirmed the effectiveness of low speed turning for eliminating the rotor thermal bending when the rotor is restarted with the maximum thermal bending.This result shows practical significance as reference for the normal startup and shutdown of the gas turbine rotor as well as its safe operation.