Zhang Mingming, Hou Anping, Han Yadong
Faculty of Science, Beijing University of Technology, Beijing 100124, China.
School of Energy and Power, Beihang University, Beijing 100191, China.
Entropy (Basel). 2021 Mar 24;23(4):383. doi: 10.3390/e23040383.
In order to explore the mechanism during the process of the non-synchronous vibration (NSV), the flow field formation development is investigated in this paper. Based on the fluid-structure interaction method, the vibration of rotor blades is found to be in the first bending mode with a non-integral order (4.6) of the rotation speed. Referring to the constant inter blade phase angle (IBPA), the appearances of frequency-locking and phase-locking can be identified for the NSV. A periodical instability flow emerges in the tip region with the mixture of separation vortex and tip leakage flow. Due to the nonlinearities of fluid and structure, the blade vibration exhibits a limit cycle oscillation (LCO) response. The separation vortex presenting a spiral structure propagates in the annulus, indicating a pattern as modal oscillation. A flow induced vibration is initiated by the spiral vortex in the tip. The large pressure oscillation caused by the movement of the spiral vortex is regarded as a main factor for the presented NSV. As the oscillation of blade loading occurs with blade rotating pass the disturbances, the intensity of the reverse leakage flow in adjacent channels also plays a crucial role in the blade vibration.
为了探究非同步振动（NSV）过程中的机理，本文对流场的形成发展进行了研究。基于流固耦合方法，发现转子叶片的振动处于转速非整数阶（4.6）的第一弯曲模态。参照恒定的叶间相位角（IBPA），可以识别出NSV的频率锁定和相位锁定现象。在叶尖区域出现了周期性不稳定流动，伴有分离涡和叶尖泄漏流的混合。由于流体和结构的非线性，叶片振动呈现出极限环振荡（LCO）响应。呈现螺旋结构的分离涡在环形空间中传播，表明其具有模态振荡模式。叶尖处的螺旋涡引发了流致振动。由螺旋涡运动引起的大压力振荡被视为所呈现的NSV的主要因素。由于叶片载荷的振荡在叶片旋转通过扰动时发生，相邻通道中反向泄漏流的强度在叶片振动中也起着关键作用。
