Micro Air Vehicle

A validation study (i.e. comparison to experimental data) of the NACA 0012 airfoil was conducted at various angles of attack (alpha). The study was done using three different grid topologies: 1) Structured O-grid, 2) Structured C-H grid, 3) Unstructured T-Rex grid. First of all, we created the grids using grid generation software named Pointwise. In this case, the provided NACA 0012 airfoil geometry was used, and the chord length was assumed to be 1 meter. Far field boundary was set approximately 50 chord lengths away from the airfoil in all directions. In order to minimize the differences between each grid topology, the wall spacing was kept same at delta s=1.0e-4, and the grid point distribution was kept same at delta d=0.01 at the both leading and the trailing edge. After grid generation, CFD++ solver was used to get the solutions at different angles of attack. After CFD++ ran the simulations and generated the data, the data was analyzed in Microsoft Excel. Coefficient of lift (Cl) was plotted against angle of attack (), and was compared with the experimental data provided. Also, the theoretical incompressible Cl was calculated using the thin airfoil theory and plotted within the same graph to compare. Coefficient of lift (Cl) was also plotted against coefficient of drag (Cd) and compared with the experimental data. After all the analysis, the conclusion was drawn that the structured grids give better results than unstructured grids if the grid resolution is done well. However, structured grid
generation takes longer time than unstructured grid. On the other hand, if we keep the wall spacing and grid point distribution same for both types of grid, then the unstructured grids give better solution accuracy than the structured grids. Though grid generation of the unstructured topology takes lesser time than structured topology, computation and execution of the codes of the unstructured topology takes higher time.

An experimental study was conducted to assess the aerodynamic benefits of flapping flight compared with fixed-wing soaring flight for the development of flapping-wing Micro-Air-Vehicles (MAVs). The time-averaged aerodynamic performances (i.e. mean lift and thrust/drag) of two flexible membrane wings with different skin flexibility (i.e., a flexible nylon wing and a very flexible latex wing) were compared with that of a

This paper presents an experimental research aiming to realize an artificial hind wing that can mimic the wing unfolding motion of Allomyrina dichotoma, an insect in coleopteran order. Based on the understanding of working principles of beetle wing folding/unfolding mechanisms, the hind wing unfolding motion is mimicked by a combination of creative ideas and state-of-art artificial muscle actuator. In this work, we devise two types of artificial wings and the successfully demonstrate that they can be unfolded by actuation of shape memory alloy wires to provide actuation force at the wing base and along the leading edge vein. The folding/unfolding mechanisms may provide an insight for portable nano/micro air vehicles with morphing wings.