Heat transfer on iced cylinders

Abstract

The convective heat transfer is the main mechanism to remove the solidification enthalpy during glaze ice accretion. Most of the airfoil icing prediction codes use a heat transfer calculation procedure based on the classical integral evaluation of the boundary layer. These icing codes consider a smooth surface in laminar regime, the fully rough surface in turbulent regime and that laminar-turbulent transition occurs abruptly without a transition region. This work presents the classical integral evaluation of the boundary layer and proposes the use of an intermittency function to represent the laminar-turbulent region. The present model is used to calculate the local heat transfer coefficient for a rough cylinder and the results are compared with experimental data and with numerical simulations of other authors. The discrepancies between the present results and the experimental data are analyzed and it is shown that an adequate calculation of the convective heat transfer requires that both equivalent sand grain roughness height and rough Stanton number shall represent the characteristics of the rough surface and it is desirable that they are determined experimentally to each type of surface. © 2010 by Her Majesty the Queen in Right of Canada.