The lift and drag coefficient plots for any airfoil provides a means for measuring its aerodynamic characteristics. These are very useful in deciding if a particular airfoil is appropriate for any particular application area. This study computationally predicts how the lift coefficient, drag coefficient and drag polar derived for the aerodynamic flow over the NACA 4412 airfoil vary with angles of attack. The effect of varying Reynolds number on the aerodynamic characteristics was also investigated. The finite-volume based computational fluid dynamics code; ANSYS Fluent was used to solve the continuity equation, the Reynolds Averaged Navier-Stokes equation and the turbulence transport equations governing the flow. For the range of Reynolds number considered, flow was taken as incompressible, steady and two-dimensional. Simulations were run for angles of attack ranging from -10° to 18° with an interval of 2° and for a Reynolds number range of 1.0 x 10 6 to 13.0 x 10 6 . Results at a given Reynolds number revealed a steady variation between lift coefficient and angle of attack within the pre-stall region and a gradually increasing curve for the drag coefficients. A constant stalling angle at 14° w ith gradually increasing value for the maximum lift coefficient was recorded as the Reynolds number increased. The drag polar was also found to be constant at 6° for all the ranges of R eynolds number. The results obtained showed that numerically solving for flow problems is a valid approach for obtaining the aerodynamic characteristics of an airfoil since the results were compared with data from wind tunnel tests.

The inadequate capacity of the Nigerian grid has necessitated the use of distributed energy resources for on-site generation. Alternative energy sources such as biogas may offer a more economic and environmentally-friendly approach to meeting energy demand when compared to fossil -based onsite generation such as the use of gasoline or diesel generators. Hybrid energy systems may also be more beneficial economically and technically. In this paper, we use HOMER, a micropower modelling and optimization software, to determine the optimal configuration of a biogas-based power system for a facility in a Nigerian University. A feasible, optimal hybrid configuration for the system was determined, considering biogas generation, diesel generation, and battery storage under certain constraints. Simulation results showed that the biogas and battery configuration is the most suitable techno-economic configuration for our design.

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