Aerodynamic Boundary Element Method for Bluff Bodies with Wind Tunnel Data Correlation

Abstract

Boundary Element Method (BEM) is a widely used technique for the aerodynamic analysis of lifting bodies, due to the good compromise between fidelity and computational costs. This is especially true in rotorcraft applications, where the effects of the rotor wake play a crucial role in the evaluation of aerodynamic loads, and CFD solvers suffer for dissipation problems. However, potential formulations are unable to simulate many phenomena, like stall or separation around non-aerodynamic (bluff) bodies. This limits they application to the aerodynamic analysis of complete aircraft/rotorcraft configurations, where massive separations might arise downstream of the fuselage. In this paper, several potential-flow, BEM methodologies are proposed, with the objective of overcoming these limitations, at the cost of receiving information concerning the position of separation point and/or the value of pressure in the separated-flow region. Numerical results concerning the assessment of the proposed BEM techniques are presented: these consist in comparisons with data available in the literature for simple-geometry bodies, and with measurements obtained by experimental tests performed in a semi-open wind tunnel facility on a light-weight helicopter fuselage.