【作者】 王超；

【导师】 王坤；

【作者基本信息】 华中科技大学 ， 热能工程， 2018， 硕士

【摘要】 汽轮发电机轴系扭振问题容易导致轴颈和联轴器等部位承受很大的扭转交变应力载荷,从而引发轴系的疲劳损伤累积,严重的低周疲劳甚至会导致轴系形成裂纹乃至断裂,及时有效的扭振故障检测和快速准确的轴系疲劳寿命损伤反馈对电力安全生产至关重要。本文在目前汽轮发电机轴系扭振冲击疲劳损伤一般分析方法的基础上,以某电厂TSR实测的机组轴系扭振现象录波数据为基础对影响评价结果的扭振模型、应力计算方法、载荷谱分析方法等几个方面展开了对比研究。首先进行了基于有限元模型和快速模态分解理论为基础的扭振疲劳分析。基于制造厂图纸在有限元软件中对轴系进行有限元(连续质量模型)建模,结合实际录波和模态计算后提取的轴系固有特性完成轴颈和低发联轴器的应力载荷谱计算,最终对四台机组此次扭振事故造成的疲劳寿命损耗进行估算。其后,进行了基于集中质量模型和瞬态分析为基础的扭振疲劳分析。在集中质量模型分析中,通过在机头施加相应角速度和角加速度约束信号,然后提取各危险轴颈的载荷谱的方式计算轴系疲劳寿命损耗。比较研究表明,对于绝大部分危险轴颈,瞬态分析法与快速模态分解方法在载荷谱趋势和大小上与比较吻合,但与机头临近两个轴颈相对差异比较大。两者最终计算得到的轴系疲劳寿命损耗比较接近。最后,针对电厂TSR存储和处理数据过于庞大的问题,本文采用两种不同的载荷谱处理方式,将非参数核密度估计算法运用于扭振事故中载荷谱处理中,并比较不同核函数和带宽对估计结果精度的影响,从而达到在保证估计精度的情况下,用较少的数据保存扭振数据特征。结果表明,不同核函数的选取对估计结果精度影响非常小,但带宽系数h的大小对估计结果精度影响非常大,h越小,其估计结果越精确。在达到较好的估计精度的前提下,采用波峰样本法可以有效减小数据存储量。更多还原

【Abstract】 The torsional vibration problems of turbine generator sets can easily lead to large torsional alternating stress load on journals and couplings,which brings in the fatigue damage accumulation of the shaftings,Severe low-cycle fatigue can even lead to cracks and fractures in the shaft system.Therefore,the timely and effective detection of torsional vibration and the ability to quickly and accurately feedback fatigue life damage are critical to the safe production of electricity.Based on the general analysis method for fatigue damage impact of the turbine generator shafts torsional vibration and the recorded data of the units,a comparative study was conducted about the influencing factors for the evaluation results,including torsional vibration model,stress calculation method,load spectrum analysis method and other aspects.Firstly,the torsional vibration fatigue analysis based on finite element model and rapid modal decomposition theory was carried out.The continuous mass model of the shafting system is modeled in the finite element software based on the drawings of the manufacturer,and the stress load spectrum calculation of the shafting journal and generator coupling is completed based on the inherent characteristics of the shafting which extracted from modal calculation,and finally the fatigue life loss of four units are calculated.Afterwards,torsional vibration fatigue analysis based on lumped mass model and transient analysis was performed.Corresponding angular velocity and angular acceleration constrained signals are applied at the nose,and load spectrum of each dangerous journal is extracted to calculate the fatigue life loss of the shaft system.The results show that the transient analysis results is consistent with fast modal decomposition method for the load spectrum of most dangerous journal.However,the difference of journals near the nose is relatively large.The final calculated shafting fatigue life is relatively close.Finally,aiming at the problem of data storing and processing for the TSR devices,two different sampling methods are used to apply the non-parametric kernel density estimation algorithm to load spectrum statistics in torsional vibration accidents.Different kernel functions and bandwidth are applied to achieve the accurate estimation results and a small calculation cost.The results show that the selection of different kernel functions has very little effect on the accuracy of the estimation.However,the size of the bandwidth coefficient h has a great influence.The smaller h is,the more accurate the estimation is.Under the premise of achieving a good estimation accuracy,the use of peak sample method can effectively reduce the amount of data storage.更多还原