Numerical simulation of 3-dimensional flow fields around an airfoil for wind turbines

Abstract

To predict and understand the low Reynolds number phenomena, such as laminar separation or formation of separation bubbles on wind turbine blades, the threedimensional (3-D) flow field around an airfoil 'MEL012' is numerically analyzed at a Reynolds number of 200,000 and an attack angle of 4 degrees. In this condition, a separation bubble is observed in wind tunnel experiments. In this work, 3-D analysis using secondorder upwind scheme for the convection term is selected as the numerical method to simulate the global flow field. The results are summarized below: (1) The numerical approach of flow field analysis around a 2-D airfoil simulates the growth of three- dimensionality and it reveals that the flow field has 3-D vortex dynamics phenomena. (2) Results using a finer grid system with grid points concentrated in the vicinity of the separation point show a discontinuity in the pressure coefficient (Cp) distribution. This discontinuity captures the formation of a separation bubble at a location which is in good agreement with experimental results.