Fluidelastic instability of a tube array is extremely important to the security of a nuclear power plant. Lots of experimental analyses were conducted on the fluidelastic instability of a tube array subjected to two-phase flow in the transverse direction. Streamwise fluid-elastic instability of a tube array has been ignored for a long time until recently observations of streamwise tube failure in a steam generator in the USA. However, there are a few theoretical analysis to calculate the critical velocity. Therefore, the streamwise fluidelastic instability of a rotated triangular tube array was studied in this paper. A mathematical model of a tube array with seven tubes was established. A program based on the model was written, and an experiment was conducted to verify the program. The numerical results were in good agreement with the experimental data. The critical velocity of streamwise fluidelastic instability considering the two-phase flow was determined by the eigenvalue analysis. The numerical results illustrate that void fraction has an obvious effect on the critical velocity and the instability mode of the streamwise fluidelastic instability of a tube array. The influences of tube natural frequency were also investigated within void fraction range from 0 to 80%. The results indicate that void fraction and tube natural frequency are the key factors in streamwise fluidelastic instability.

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两相流中旋转三角管阵列的流体弹性不稳定性的理论研究

管阵列的流体弹性不稳定性对于核电站的安全极为重要。对于在横向上经受两相流的管阵列的流体弹性不稳定性进行了许多实验分析。直到最近在美国观察到蒸汽发生器中沿流方向的管道破裂的现象之前，人们一直忽略了管阵列的沿流方向的弹性流动的不稳定性。但是，有一些理论分析可以计算出临界速度。因此，本文研究了旋转三角管阵列的流向流体弹性不稳定性。建立了具有七个管的管阵列的数学模型。编写了基于模型的程序，并进行了实验以验证程序。数值结果与实验数据吻合良好。通过特征值分析确定了考虑到两相流的流向流体弹性不稳定性的临界速度。数值结果表明，空隙率对管阵列的流态流弹性失稳的临界速度和失稳模式有明显的影响。还研究了在0至80％的空隙率范围内管固有频率的影响。结果表明，孔隙率和管固有频率是影响流态流弹性失稳的关键因素。数值结果表明，空隙率对管阵列的流态流弹性失稳的临界速度和失稳模式有明显的影响。还研究了在0至80％的空隙率范围内管固有频率的影响。结果表明，孔隙率和管固有频率是影响流态流弹性失稳的关键因素。数值结果表明，空隙率对管阵列的流态流弹性失稳的临界速度和失稳模式有明显的影响。还研究了在0至80％的空隙率范围内管固有频率的影响。结果表明，孔隙率和管固有频率是影响流态流弹性失稳的关键因素。