The flow around a flat plate has intrigued researchers for a long time. The majority of research has been on the flow around a normal flat plate. With the advent of Micro Aerial Vehicles (MAVs) and their widespread applications, the use of flat plate as a lift generation device has drawn utmost attention, and therefore, it needs to be investigated further. Usually, fixed wing MAVs work in the range of Reynolds number, Re =104 – 105, and it is reported that a flat plate shows a better lift-to-drag ratio in this range of Re as compared to conventional airfoils. The aim of this investigation is to understand the aerodynamic characteristics of a flat plate at low Re and its applicability on fixed wing MAVs. In this regard, a two-dimensional computational study using the Spalart-Allmaras turbulence model is conducted to observe the flow around a flat plate for Re in the order of 104. Two flat plates having thickness ratios of 1% and 3% are considered in the present study. In each case, the trailing edge vortices are studied and the corresponding Strouhal number is calculated. The frequency of fluctuating velocity is analyzed for the calculation of Strouhal number. It is observed that the periodic velocity fluctuation starts in the wake region at angle of attacks (AoA) beyond 9o. Computations conducted at two different Re show that the frequency of fluctuating velocity is higher at the higher Re. The general observation is that the Strouhal number decreases with the increase of AoA. The surface pressure and flow characteristics along with the lift and drag coefficients (CL, CD) are also analyzed. The flat plate having 1% thickness ratio shows a better CL/CD ratio than the flat plate with 3% thickness ratio. The thinner plate provided lesser resistance to the flow which leads to a reduction in the CD. The pressure distribution along the flat plate has also been plotted and compared to that of a conventional low Re airfoil, S5010. For the Re under investigation, the difference in pressure between the suction side and pressure side is found to be higher for the flat plate at higher AoAs. This results in a greater lift force in case of the flat plate as compared to the conventional airfoil. The lift and drag forces are calculated to ascertain its feasibility as wings for MAV application. The prospect of using flat plate as wings on MAV could greatly reduce its manufacturing complexity and usher a new era of widespread MAV utilization.

Aerodynamic Analysis of Flat Plates as Lift Generating Devices for Micro Aerial Vehicles

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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