Author(s) :

John Doan.

Volume/Issue :

Abstract :

The lift force, drag force, and lift-to-drag ratio are essential performance metrics for any airfoil. Several studies have investigated these aerodynamic forces over a range of Reynolds numbers, but critically, detailed investigation of how the aerodynamic forces vary with response to independent changes in velocity, density and viscosity are scarce. Additionally, how the lift-to-drag ratio varies with the Reynolds number, Re, and individual variables within the Reynolds number is also unclear. In this study, computational fluid dynamics is used to assess the aerodynamic forces acting on an arbitrary airfoil over 3.3 × 10^2 < Re < 6.8 × 10^6 by independently varying fluid velocity, density and viscosity. The lift-to-drag ratio was found to be approximately constant for 9.8 × 10^5 < Re < 6.8 × 10^6. At Re = 3.3 × 10^4, the lift-to-drag ratio was found to depend on the specific variables used to alter Re, likely due to shear force becoming more significant at low Re. Results from this work provide compelling evidence that the lift, drag, and lift-to-drag ratio vary not only as a result of variation of Re but also due to independent variation of components of Re. Future studies analyzing different metrics with respect to Re should specify what variables are varied to avoid ambiguity.