This special vibration frequency,4.56f,was observed in the vibration spectrum for upper and low brackets,especially in horizontal vibration results,although the level is not so high.
尽管振动水平不高,但在上下托架的振动光谱中观察到了4.56f这种特殊振动频率,尤其是在水平振动结果之中.
3.2.2 Pressure fluctuation
3.2.2压力波动
As mentioned above,the pressure transducers located at the inlet of spiral case indicated that the inlet flow is in good condition whenever the load is low or high.Figure 9 presents the pressure fluctuation at the inlet of spiral case at the load of 540.6 MW.It can be found that the level of the pressure fluctuation is very low.Simultaneously,the pressure fluctuation under the head cover exhibits the similar features,as shown in Fig.10.The amplitude is less than 1 kPa at this special load.No evident dominant frequency with large fluctuation level was found for the pressure fluctuation.However,the pressure fluctuation in draft tube revealed a different frequency spectrum,as shown in Fig.11.
如上所述,位于水轮机蜗壳进水口处的压力传感器表明,无论载荷高低,进水流量的状况很好.图9显示了荷载为540.6 MW时蜗壳进水口处的压力波动.可以发现压力波动的水平很低.同时,顶盖下的压力波动也显示出类似特征,如图10所示.在这个特殊荷载时的振幅小于1 kPa (千帕).在此种压力波动水平时,没有发现大波动水平下的明显主频.然而,尾水管(吸出管)处的压力波动显示出不同的频谱,如图11所示.