Design of Optimized Profiles for Stall Regulated HAWTs: Part 1: Design Concepts and Method Formulation

The paper presents a methodology developed for the design of optimized airfoils for stall regulated HAWTs. Given optimized lift and drag characteristic curves for maximum energy capture, the method focuses on the design of the corresponding profile shape. Although the problem is a multi-disciplinary one, the present design philosophy is based on a s ingle-point approach, which, through an iterative procedure aims to achieve the best possible compromise of the imposed requirements. The adopted methodology is based on a combination of an inverse viscous and an inverse inviscid constituent. The viscous part provides an optimized suction side velocity distribution for a given Reynolds number. A compatible pressure side velocity distribution is then constructed for the given design lift coefficient. At a final stage the profile shape is provided by the inverse inviscid solver using an iterative procedure to effect profile closure automatically. The resulting profile performance is fully assessed using a direct viscous-inviscid interaction method. Four new profiles were designed. Three of them correspond to the hub, mid and tip sections of an optimized HAWT rotor. The fourth was designed for lower Reynolds number operation and was wind tunnel tested at Southampton University. The design philosophy, the new profiles and their characteristic curves are presented in Part 1 of the paper. The detailed characteristics of the optimized profiles are discussed in the companion Part 2 paper.