This paper presents direct numerical simulations (DNS) on unsteady turbulent flow in a vibrating low-pressure turbine blade cascade to predict the flutter instabilities and explores the effects of blade oscillations on the flow structure and flow separation point. The spectral/hp element method is employed for the three-dimensional simulations of the domain. This method enables capturing more details about the flow structure and vortex generations compared to the URANS methods. The method can aid in understanding the physics of these complex fluid–structure interaction problems while it requires much less computational time compared to the other DNS models. The blade vibration frequency is varied from 5.2 Hz to 10.3 Hz with maximum vibration amplitude of 3% of chord length at the blade tip. The results illustrate that the vortex generation becomes stronger over the blades with higher vibration frequencies compared to the stationary ones. The main reason for the additional vortex generation and recirculations over the oscillating blades is the additional flow disturbance due to blade vibration and its interactions with the shear-layer on the turbine blade cascade. It is seen that the vortex shedding is growing around the trailing edge and become stronger on the suction surface of the vibrating blade. The flow separation over the suction surface of the stationary blade occurs at $S_{\mathrm{sep}}∕S_0=0.391$, while it occurs at 0.372 over the oscillating blade with $f=5.2\mathrm{Hz}$.

本文介绍了振动低压涡轮叶栅中非定常湍流的直接数值模拟 (DNS)，以预测颤振不稳定性，并探讨叶片振荡对流动结构和流动分离点的影响。光谱/hp 元素方法用于域的三维模拟。与 URANS 方法相比，该方法能够捕获有关流动结构和涡流生成的更多细节。该方法可以帮助理解这些复杂的流固耦合问题的物理原理，同时与其他 DNS 模型相比，它需要的计算时间要少得多。叶片振动频率从 5.2 Hz 到 10.3 Hz 不等，最大振幅为叶片尖端弦长的 3%。结果表明，与静止叶片相比，具有更高振动频率的叶片产生的涡流更强。在振荡叶片上产生额外涡流和再循环的主要原因是由于叶片振动及其与涡轮叶栅上剪切层的相互作用而产生的额外流动扰动。可以看出，涡旋脱落在后缘周围逐渐增大，并在振动叶片的吸力面上变强。静叶片吸力面上的流动分离发生在 在振荡叶片上产生额外涡流和再循环的主要原因是由于叶片振动及其与涡轮叶栅上剪切层的相互作用而产生的额外流动扰动。可以看出，涡旋脱落在后缘周围逐渐增大，并在振动叶片的吸力面上变强。静叶片吸力面上的流动分离发生在 在振荡叶片上产生额外涡流和再循环的主要原因是由于叶片振动及其与涡轮叶栅上剪切层的相互作用而产生的额外流动扰动。可以看出，涡旋脱落在后缘周围逐渐增大，并在振动叶片的吸力面上变强。静叶片吸力面上的流动分离发生在${秒}_{\mathrm{九月}}∕{秒}_0=0.391$，而它发生在摆动叶片上的 0.372 处， $F=5.2\mathrm{赫兹}$.