Immersed Boundary Method for Rotorcraft Aerodynamics Using OpenFOAM

Abstract

The rotorcraft CFD literature review showed that efficient, easy to apply, and computationally less expensive methods are still a need for the design and performance predictions of rotorcraft. Immersed Boundary Method (IBM) and Virtual Blade Model (VBM) based simulations have the potential to minimize the user input and computational expense while providing reasonably accurate results. Distinctive property of the IBM method is that, the whole simulation is run on a Cartesian grid that does not conform to the solid boundary. So that, in order to define the boundary conditions, the governing equations near solid boundaries are modified. Virtual Blade Model is a validated and verified way of modeling the aerodynamics of the rotors. It provides the benefit of using Navier-Stokes equations, instead of wake modeling, without being computationally expensive. In this work, an IBM code from a different study and VBM is integrated in the finite volume based Navier-Stokes solver Open Field Operation and Manipulation (OpenFOAM) platform specifically for rotorcraft simulations. The integrated code is verified and validated with the extensively studied wind tunnel experiment of a rotorcraft in forward flight. Finally, the result is compared and discussed against body conformal methods. Although some differences are observed, it is concluded that the results are on par with the body-conformal methods.