A novel hybrid method for helicopter cost effective aeroelastic simulations

Abstract

Aiming at increasing the fidelity of aeroelastic simulations for helicopter configurations without excessively penalizing the computational cost, a novel hybrid flow solver is proposed. The widely used domain decomposition technique is given a different twist by also differentiating the method used in the sub-domains. The proposed solver combines grid based CFD with particle methods. To every blade a confined CFD grid is defined with an extent of ~1 chord. To this set-up a background flow is added defined in particle form. The formulation is compressible and so particles carry mass, vorticity, dilatation and pressure. A two-ways coupling of the two solvers is implemented. The background flow is used in providing the outer boundary conditions of the CFD grids while the CFD solution is used in order to update the information carried by particles that are contained in the CFD grids. For the aeroelastic simulations a multi-body structural solver is used. The blades are considered slender Timoshenko beam structures. Geometrical non-linearities are accounted for by subdividing every blade into sub-bodies that are subsequently treated separately while the equilibrium equations are implicitly formulated with respect to the coupling with flow through an iterative flow-to-structure interaction. The present work includes the description of the methodology and representative results taken from the HeliNoVi data base.