Journal of Bionic Engineering

Volume 14, Issue 4, October 2017, Pages 746-758

Loan Thi Kim Au, Hoang Vu Phan, Hoon Cheol Park

Department of Advanced Technology Fusion and Artificial Muscle Research Center, Konkuk University, Seoul, Korea

Abstract  In previous work, we modified blade element theory by implementing three-dimensional wing kinematics and modeled the unsteady aerodynamic effects by adding the added mass and rotational forces. This method is referred to as Unsteady Blade Element Theory (UBET). A comparison between UBET and Computational Fluid Dynamics (CFD) for flapping wings with high flapping frequencies (>30 Hz) could not be found in literature survey. In this paper, UBET that considers the movement of pressure center in pitching-moment estimation was validated using the CFD method. We investigated three three-dimensional (3D) wing kinematics that produce negative, zero, and positive aerodynamic pitching moments. For all cases, the instantaneous aerodynamic forces and pitching moments estimated via UBET and CFD showed similar trends. The differences in average vertical forces and pitching moments about the center of gravity were about 10% and 12%, respectively. Therefore, UBET is proven to reasonably estimate the aerodynamic forces and pitching moment for flight dynamic study of FW-MAV. However, the differences in average wing drags and pitching moments about the feather axis were more than 20%. Since study of aerodynamic power requires reasonable estimation of wing drag and pitching moment about the feather axis, UBET needs further im-provement for higher accuracy.

Key words：blade element theory      unsteady      computational fluid dynamics      flapping wings      biomimetic

Full text is available at http://www.sciencedirect.com/science/article/pii/S1672652916604407