Insects can hover, move laterally or backward, even fly upside down. Their superior flying capability, together with the recent development in Micro-Electro-Mechanical Systems (MEMS) technology has inspired great interest in designing tiny aerial robots modelled after the insect. Industry, commerce and the military have all identified potential roles for such micro-air vehicles (MAVs), especially where human involvement is considered difficult or dangerous.
Our research project focuses on the unsteady aerodynamics of the flapping wings of insects using both experimental and computational tools developed at NUS.
3D Flapping Wing Facilities
Two 3-D flapping mechanisms, namely hovering and forward flight, have been built for the projects.
Both the mechanisms incorporate compact force sensors for direct measurements of aerodynamic forces. They can generate any predetermined flapping motion such as fruitfly and hawkmoth insects hovering motion.
The purpose of the 2-D experiments is to conduct fundamental study on the unsteady flow of flapping wings in an isolated and simplified condition.
Two 2-D flapping mechanisms have been built, one for hovering and the second one for forward flight experiment.
2-D flapping mecahnism for hovering in a rectangular tank: DPIV and force measurements
2-D Flappping mechanism for forward flight in a re-circulating water tunnel: DPIV measurements
The following shows the lift generatd by a hovering Hawkmoth wing over one cycle of flapping:
Numerical Study (SVD-GFD Scheme)
This computational scheme solves incompressible viscous flow problems with complex geometry and moving boundaries on a hybrid meshfree-Cartesian grid. Spatial discretization is carried out by a combination of standard finite difference and singular value decomposition generalised finite difference (SVD-GFD) approximations. Convecting nodes are treated by an arbitrary Lagrangian-Eulerian formulation of the Navier-Stokes equations.
The video on your left shows the unsteady flow around a flapping wing model, showing steamtraces and pressure distributions during a flapping cycle - plan view.
The picture on your right reflects the unsteady flow around a flapping wing model, showing stamtraces and pressure distributions during flapping cycle - side view towards body.