Aerodynamic Study of a Flapping-Wing NAV Using a Combination of Numerical and Experimental Methods

The development and acquisition of a new class of military systems known as Nano Air Vehicle (NAV) is possible in not too distant a future as a result of technological progress in a number of areas. These vehicles will likely use flapping wings as there is strong evidence that for very small craft, flapping-wing performance is superior to other options due to dynamic effects that create much higher average lift at low Reynolds numbers. An essential step towards engineering realization of flapping-wing flight is the understanding of the issues for the fully 3-D motion. In this paper, we present an approach adopted towards that objective. Based on system considerations, the general characteristics of a notional NAV to be studied such as size, mass, and wing motions were established. Then, three methods were developed and applied to the notional NAV. The detailed flow physics is captured using accurate Navier-Stokes CFD solutions and a tailored designed instrumented rig in a water tunnel. A vortex-lattice based engineering-type model, refined with the higher accuracy CFD and experimental results, was developed and will be used to efficiently study a variety of prescribed wing shapes and flapping patterns.