New simulation strategy for an oscillating cascade in turbomachinery using immersed-boundary method

Based on the immersed-boundary method, a numerical simulation for an oscillating cascade is established and the relevant analysis is presented with emphasis on the physical understanding of fluid-structure interaction. To validate the method, two simulation cases, an oscillating circular cylinder at a low Keulegan-Carpenter number and a flapping airfoil, are performed and the results are in good agreement with the previous research. In the oscillating cascade simulation, it is found that the reduced velocity U* is a very sensitive factor which affects the critical stable boundary in the present examples. On the other hand, the effects of interblade phase angles on the system stability are also discussed. In particular, it is worth noting that the same process is applied to several test cases without generating any body-fitting grid. Therefore, the method shows a significant time savings in the computational process for such a complicated fluid-structure interaction problem.