Propulsion performance investigation of bio-inspired nano rotor base on fluid-structure interaction

In this paper, the bio-inspired blade motion is introduced to improve the propulsive performance of nano rotor at an ultra-low Reynolds number. However, the complex flow interacts with the flexible composite blade structure resulting in the change of nano rotor propulsion performance and the vibration of blade structure. A composite nano rotor with blade-pitch motion is investigated computationally with a computational solvers based on fluid-structure interaction. The finite element model for the composite rotor is created and verified with a non-contact modal test. It is found that the simulation results matched well with the experimental results. Successively, the propulsive performance of a rigid nano rotor is studied. The propulsive performance of the nano rotor is analysed at different bio-inspired pitch frequencies. The results show that the figure of merit of the bio-inspired pitch rotor increases because of the bio-inspired blade pitch motion. And it is also found that the improvement of the propulsive performance of the nano rotor varies with the pitch frequency. The propulsive performance of the flexible bio-inspired nano rotor is also studied with by using fluid-structure interaction method. It is found that the computational results for flexible nano rotor are lower than that for rigid nano rotor. It is evident that it is necessary to consider the flexibility of the composite nano rotor when investigating the propulsion performance of bio-inspired nano rotor. And the response of blade structure is also studied. Structural dynamic analysis shows that the blade structure vibrates with small amplitude. And two peak values are found at the rotation frequency and the fundamental frequency of the nano rotor structure.