Heat Transfer Coefficient Measurement on Iced Airfoil in Small Icing Wind Tunnel

Abstract

The local convective heat transfer coefe cient distribution is measured on an iced airfoil in a small closed-loop icing tunnel at the Centre d’ Essais des Propulseurs, the French engine test center. The airfoil surface is heated with a modulated laser source, and the heat e ux variation of the ice is recorded with an infrared camera. The method is validated on a cylinderin dry air and in icing conditions. Themethod isthen applied to a 145-mm-chord airfoil covered with typical rime, glaze, and mixed ice shapes. The effect of air velocity is studied by performing tests at airspeeds from 80 to 123 m/s (Reynolds numbers from 1 :25 ££ 10 6 to 1:9 ££ 10 6). It was found that the heat transfer coefe cient strongly depends on the surface condition of the ice. In relatively smooth zones, values are approximately equal to 400 W/m 2± C, whereas values greater than 1000 W/m 2± C are observed in nonuniform and rough areas. Results and limitations of the method are discussed and compared to numerical results obtained on similar ice shapes.